July 3-7, 2015 · July 3-7, 2015 Tohoku University, Sendai, Japan. i Published by ICVS2015 Organizing Committee 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan

ICVS 2015Tohoku University, Sendai, Japan

July 3-7, 2015

Hotel MontereySendai

JR Sendaistation

Sendai Washington

Hotel

Hotel Metropolitan

Sendai

Hotel Pearl City

Sendai

Arc Hotel Sendai

Aoba-dori

Sakura Hall(conference venue)

RIEC(lunch)

Tohoku UniversityKatahira campus

SendaiKokusai

Hotel

The 23rd Symposium of the

International Colour Vision Society

Abstract Book

July 3-7, 2015Tohoku University, Sendai, Japan

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Published by ICVS2015 Organizing Committee2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan 　

The 23rd Symposium of the International Colour Vision SocietyAbstract Book

Editors: Keiji Uchikawa, Kowa Koida, Ichiro Kuriki, Yoko Mizokami

ISBN: 978-4-9908469-0-9

(c) 2015 ICVS2015 Organizing Committeehttp://www.vision.riec.tohoku.ac.jp/ICVS2015/ All rights reserved.

DisclaimerMatters of accuracy and copyright for text associated with the papers published in the ICVS2015 Abstract Book remain with the authors. The ICVS and ICVS2015 Organizing Committee do not accept responsibility for any errors or liabilities that may arise from the publication of the abstracts.

CopyrightReproduction of this document or parts thereof by any means whatsoever requires prior written permission from ICVS2015 Organizing Committee. Each abstract published in the book remains the intellectual property of the individual author(s) and/or their indicated institutions.

Tohoku University2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan

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PREFACE

Dear Colleagues,

It is a great pleasure that we welcome you to Sendai for the 23rd Symposium of the International Colour Vision Society.

In the past symposiums the society has succeed in attracting a wide variety of interests in colour vision from basic to applied and clinical fields all over the world. The society also continues to attract the members by friendly exchanges and discussions among attendants in the symposiums. We hope this symposium (ICVS2015) inherits and develops this great tradition of the society through technical and social programmes.

We are delighted that many scientists and students from 20 countries will bring their recent research and great enthusiasm to ICVS2015 and this symposium will be well attended. A total number of the participants are over 130 and that of the presentations are more than 100.

The social and cultural programme will uncovers historical and cultural appearances in architecture, landscape and true Japanese tastes in Sendai, one of the oldest cities in Japan. We will be most pleased to provide an atmosphere for informal interactions among all people in order to facilitate forming new friendships.

We are deeply grateful for the all supports of ICVS2015, in particular, sponsors, foundations, Tohoku University, and the ICVS officers and directors. We wish all participants to ICVS would enjoy the symposium and a wonderful stay in Sendai.

The Organizing Committee

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ICVS2015 OFFICERS

PresidentJohn MollonDepartment of Experimental Psychology,University of Cambridge, Cambridge, UK

General SecretarySteven BuckDepartment of Psychology, University of Washington, Seattle, WA, USA

TreasurerNeil ParryManchester Royal Eye Hospital, Manchester, UK

ICVS2015 COMMITTEEOrganizing CommitteeKeiji Uchikawa, ChairDepartment of Information Processing, Tokyo Institute of Technology, Tokyo, Japan

Kazuho FukudaDepartment of Information Design, Kogakuin University, Tokyo, Japan

Kowa KoidaElectronics-Inspired Interdisciplinary Research Institute, Toyohashi University of Technology, Toyohashi, Japan

Ichiro KurikiResearch Institute of Electrical Communication,Tohoku University, Sendai, Japan

Kazumichi MatsumiyaResearch Institute of Electrical Communication,Tohoku University, Sendai, Japan

Yoko MizokamiGraduate School of Advanced Integration Science, Chiba University, Chiba, Japan

Takehiro NagaiGraduate School of Science and Engineering, Yamagata University, Yonezawa, Japan

Shigeki NakauchiDepartment of Computer Science and Engineering, Toyohashi University of Technology, Toyohashi, Japan

Kenji YokoiDepartment of Applied Physics,National Defense Academy of Japan, Yokosuka, Japan

Advisory BoardHidehiko KomatsuNational Institute for Physiological Sciences, Okazaki, Japan

Satoshi NakadomariNational Rehabilitation Center for Persons with Disabilities, Tokorozawa, Japan

Keizo ShinomoriSchool of Information / Research Institute, Kochi University of Technology, Kochi, Japan

Sei-ichi TsujimuraDepartment of Information Science and Biomedical Engineering, Kagoshima University, Kagoshima, Japan

Hirohisa YaguchiGraduate School of Advanced Integration Science, Chiba University, Chiba, Japan

Yasuki YamauchiGraduate School of Science and Engineering, Yamagata University, Yonezawa, Japan

ICVS2015 BOARD OF DIRECTORS

Rigmor BaraasDepartment of Optometry and Visual Science,Buskerud University College, Kongsberg, Norway

Valérie BonnardelDepartment of Psychology, The University of Winchester, Winchester, UK

Jan KremersDepartment of Biology, University of Erlangen-Numberg, Erlangen, Germany

Paul MartinSave Sight Institute, University of Sydney, Sydney, Australia

Sérgio NascimentoCentre of Physics, University of Minho, Braga, Portugal

Jay NeitzDepartment of Ophthalmology,University of Washington, Seattle, USA

Steven ShevellDepartment of Psychology, University of Chicago, Chicago, USA

Hannah SmithsonDepartment of Psychology, University of Oxford, Oxford, UK

Keiji UchikawaDepartment of Information Processing, Tokyo Institute of Technology, Tokyo, Japan

John S WernerOphthalmology and Vision Science, University of California, Davis, Sacramento, USA

Qasim ZaidiDepartment of Vision Sciences, SUNY College of Optometry, New York, USA

DALTONIANA NEWSLETTER EDITORS

Dingcai CaoDepartment of Surgery, University of Chicago, Chicago, USA

Andrew ZeleSchool of Optometry, Queensland University of Technology, Brisbane,Australia

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Verriest Medalist 2015

John S Werner

Professor Werner received his Ph.D. from Brown University under the supervision of Professor Billy Wooten in the Walter S. Hunter Laboratory of Psychology. He conducted postdoctoral research with Professor Jan Walraven at the Institute for Perception - TNO in Soesterberg, The Netherlands. He was a member of the Psychology faculty at the University of Colorado, Boulder and is presently a Distinguished Professor of Ophthalmology at the University of California Davis where also holds appointments in Vision Science, and Neurobiology, Physiology & Behavior.

An active member of ICVS and of it predecessor, IRGCVD, he is also a fellow of the American Association for the Advancement of Science, American Psychological Association, American Psychological Society, Association for Research in Vision and Ophthalmology, the Gerontological Society of America and the Optical Society of America. He received the Pisart Vision Award from Lighthouse International and he presented the University of Colorado, Boulder distinguished research lecture and the Optical Society of America Robert M. Boynton lecture.

He has made important contributions to our knowledge of the development and aging of color mechanisms using psychophysics, VEP’s and most recently optical imaging techniques, OCT and adaptive optics. He has contributed to our understanding of the processes of aging in perception particularly as they relate to plasticity and potential clinical applications. Throughout his career he has maintained an active interest in opponent color mechanisms, color in art and color illusions.

A generation of vision scientists has enjoyed the benefits of reading the many books he has coedited. These include, Visual Perception: The Neurophysiological Foundations, Color Vision: Perspectives from Different Disciplines, The Visual Neurosciences, and The New Visual Neurosciences, which like Professor Werner’s own research have brought together discoveries from anatomy, physiology and psychophysics to illuminate fundamental mechanisms underlying human perception.

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General Information

Conference venue1. Do not smoke on campus. All facilities of Tohoku University are smoke free. You have to smoke at the

outside of the campus.2. Food and beverages can be brought in the building, but not to the conference room on the upper

level. 3. Free WiFi Internet access will be available in Sakura-hall building. Please check SSID and password

at the registration desk. If you have an eduroam ID, it also works inside the building.4. Coffee and some sweets will be served between talk sessions.5. We do not have a cloakroom/checkroom. But most hotels would hold your luggage on the day of

arrival/departure, even before/after the check in/out. Please contact your hotel for further information. Also, coin-operated lockers can be found at the Sendai Station. You may bring your luggage to the conference venue, but we cannot be responsible for any trouble.

6. Entrance of the Sakura-hall building is open from 8:00 am to 8:00 pm. Please consider that everyone (including staffs) has to leave the building by that time.

Presentations1. Please prepare your computer for oral presentation. Analog (D-sub 15 pins) and digital (HDMI)

connections are available. Bring adapters for these interface, if necessary, and please check connections before your session begins.

2. Time slot for general presentations is 15 minutes, including questions and answers.3. Posters can be put up in the morning of the second day. Presenters of odd/even numbered posters

have to attend during duty hours in the afternoon on 4th/6th July. 4. All posters have to be put up until the end of the meeting.

Reception (evening, July 3)1. Reception takes place on the evening of the first day of the conference. Some food and beverages

will be served around the reception desk.2. A local folk dance (“Suzume odori”; literally means “sparrow’s dance”) will be performed by a Sendai-

based group, in the middle of the reception.

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Lunch (July 4 and 6)1. Lunch on the second and fourth day will be served at a different building: Research Institute of

Electrical Communication, which is located about 3-5 minutes on foot from the conference venue. We will provide a map.

2. Please identify yourself on arrival, if you have requested special arrangement on meal.

Excursion (July 5)1. We will visit one of the sites of tsunami aftermath: Arahama Elementary School on the seaside, which

was hit by tsunami on March 11th, 2011. An officer from Reconstruction Section of Sendai-city office will kindly give a guide. English translation will be provided. After then, we will take a 1.5 hours ride on a boat from Shiogama port to Matsushima port.

2. We move between these sites (except between ports) by bus. The bus leaves Sakura Hall after taking a group photo.

3. Please pick up your lunch pack before getting on the bus. You will be encouraged to take your lunch on the bus, if possible.

4. There’s no public transportation around the Arahama Elementary School, because this area is almost ruined. Please do not miss the bus.

5. Beverages (both alcoholic and non-alcoholic) and light meal will be served on the boat.6. Returning bus from Matsushima (arrival port) to Sendai city centre leaves on time at 6:30pm. But

relatively frequent public transportation is available; e.g., JR trains run from Matsushima-kaigan station to Sendai station at every 20-30 minutes, and costs about 400 yen. You may leave the group to hang around more, at your own responsibility.

Banquet (July 6)1. We will have a banquet at a restaurant Shokeikaku, which uses the house of former ruler of the

Sendai area: Date clan.2. Public transportation (route bus) around the banquet venue is not frequent. Don’t miss the bus.3. Bus leaves at 6:00 pm. Accompanying persons who will join the banquet are expected to wait for the

bus at the reception by that time.4. Both bus and banquet venue is fully booked. Please understand that seating may be a bit tight.5. Please identify yourself on arrival, if you have requested special arrangement on meal. Also please

understand that not all meal requests can be fully satisfied.

Enjoy the conference!

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FRIDAY 3rd JULY

09:00 - 11:30 Directors' committee meeting10:30 Registration desk open13:30 - 13:45 Opening

COMPARATIVE COLOUR VISION & PHYSIOLOGYChair: Jan Kremers, Kowa Koida

13:45 - 14:00 Do we need a new determination of complementary wavelengths? …………… 2 John Mollon

14:00 - 14:15 Color and luminance selectivity of neurons in the monkey inferior temporal cortex………………………………………………………………………………………… 3 Kowa Koida

14:15 - 14:30 The effects of stimulus size on rod and cone driven ERG responses ………… 4 Jan Kremers, Avinash Aher, Tina Tsai

14:30 - 14:45 Electrophysiological responses mediated by single photoreceptor types in mice with human L-opsin ……………………………………………………………………… 5

Tina Tsai, Jan Kremers, Jenny Atorf, Maureen Neitz, Jay Neitz

14:45 - 15:00 Behavioural evidence of scotopic colour vision in amphibians ………………… 6 Carola AM Yovanovich, Almut Kelber

15:00 - 15:30 Coffee break

CHROMATIC MECHANISMS 1Chair: Neil RA Parry, Takehiro Nagai

15:30 - 15:45 Effects of luminance and isoluminance stimuli on perceived stability across saccadic eye movements: a study of the blanking effect ………………………… 7

Satoshi Shioiri, Kazumichi Matsumiya, Masayuki Sato

15:45 - 16:00 A dim view of M-cone increments ……………………………………………………… 8 Neil RA Parry, Declan J McKeefry, Jan Kremers, Ian J Murray

16:00 - 16:15 Luminance-dependent long-term chromatic adaptation …………………………… 9 Joris Vincent, Alex Kale, Steven L Buck

16:15 - 16:30 Color discrimination, cones and natural scene statistics ………………………… 10 Jenny M Bosten, Donald IA MacLeod

16:30 - 16:45 Short break

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INVITED TALK 1Chair: Steven Buck

16:45 - 17:30 Colorvisioninbutterflies ……………………………………………………………… 11 Kentaro Arikawa

17:30 - 18:00 Short break18:00 - 20:00 Reception

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SATURDAY 4th JULY

08:30 Registration desk open

CHROMATIC MECHANISMS 2Chair: Caterina Ripamonti, Tatsuya Yoshizawa

09:00 - 09:15 Melanopsin-based color percepts ……………………………………………………… 13 Dingcai Cao, Pablo A Barrionuevo

09:15 - 09:30 Relativeweightsofconeandmelanopsincellsfortheflickerdetectionmechanism ………………………………………………………………………………… 14

Sei-ichi Tsujimura, Katsunori Okajima

09:30 - 09:45 Does physical fatigue affect colour vision? ………………………………………… 15 Manca Tekavcic Pompe, Bor Tekavcic, Mirjam Lasan, Radoje Milic

09:45 - 10:00 Developmental changes in chromatic discrimination at 5-14 years …………… 16 Caterina Ripamonti, Sarah Kalwarowsky, Marko Nardini

10:00 - 10:15 AnanalyticalmodeloftheinfluenceofconesensitivityandnumerosityontheRayleigh match …………………………………………………………………………… 17

Zhaoping Li, Joseph Carroll


COLOUR VISION DEFICIENCYChair: Sérgio MC Nascimento, Hirohisa Yaguchi

10:45 - 11:00 Assessing the effects of dynamic luminance contrast noise masking on a color discrimination task ……………………………………………………………………… 18

João MM Linhares, Catarina AR João, Eva DG Silva, Leticia Álvaro, Jorge LA Santos, Vasco MN Almeida, Sérgio MC Nascimento

11:00 - 11:15 Colour vision for schoolchildren ……………………………………………………… 19 Masaru Miyao

11:15 - 11:30 New pass / fail threshold limits consistent with Holmes-Wright lanterns ……… 20 Marisa Rodriguez Carmona, Joseph D Hickey, John L Barbur

11:30 - 11:45 Colour sense for boat licence tests …………………………………………………… 21 Yasuyo Takayanagi

12:00 - 13:30 Lunch

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INVITED TALK 2Chair: Barry B Lee

13:30 - 14:15 Evolutionarydiversityofcolourvisioninprimates:implicationsfromfieldandgenetic studies …………………………………………………………………………… 22

Shoji Kawamura

14:15 - 15:15 Poster 115:15 - 15:45 Coffee break15:45 - 16:30 Poster 1

AFFECTED COLOUR VISIONChair: John L Barbur, Sei-ichi Tsujimura

16:30 - 16:45 Loss of colour vision in diabetes ……………………………………………………… 23 John L Barbur, Imran Ansari, Chris Canning

16:45 - 17:00 Longitudinal measurement of cone density in congenital achromatopsia …… 24 Christopher S Langlo, Frederick Collison, Phyllis Summerfelt, Carol White, Alfredo

Dubra, William Hauswirth, Gerald Fishman, Joseph Carroll

17:00 - 17:15 Age-relatedchangesintheimpulseresponsetoL-coneONandOFFflashes. ………………………………………………………………………………………………… 25 Keizo Shinomori, John S Werner

VERRIEST LECTURE

17:15 - 17:30 Introduction Keizo Shinomori

17:30 - 18:30 Surprising Observations about Aging Human S-Cone Pathways ……………… 26 John S Werner

THE "DRESS" SESSION (INFORMAL) Chair: Qasim Zaidi

18:30 - 20:00 Color science behind percepts of the blue-black/white-gold dress……………… 27

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SUNDAY 5th JULY


ISIHARA SYMPOSIUMChair: Keiji Uchikawa, Dingcai Cao

09:00 - 09:20 Invitedtalk:Prof.IshiharaandIshiharatestforcolourblindness ……………… 29 Mitsuru Sawa

09:20 - 09:35 S-cone spatial acuity test may reveal S-cone dysfunction not easily detected by pseudo-isochromatic tests ……………………………………………………………… 30

Lene A Hagen, Stuart J Gilson, Rigmor C Baraas

09:35 - 09:50 Characteristics of Ishihara pseudo-isochromatic test plates in LMS cone space ………………………………………………………………………………………… 31

Keiji Uchikawa, Yumiko Muto, Kazuho Fukuda

09:50 - 10:05 Abilityoffemalecolorblindgenecarriermonkeysinbreakingcolorcamouflageand discriminating colors ……………………………………………………………… 32

Kanthi A Widayati, Bambang Suryobroto, Atsuko Saito, Akichika Mikami

10:05 - 10:15 General discussion10:15 - 10:45 Coffee break

SPECIALSESSIONINTHEMEMORYOFDR.LANTHONYChair: John Mollon

10:45 - 11:00 Remark: Philippe Lanthony, our friend (1929-2014) ………………………………… 33 André Roth

11:00 - 11:15 Newinsightsintocongenitalcolourdeficiencyandvisualsearch ……………… 34 Joseph D Hickey, Marisa Rodriguez Carmona, John L Barbur

11:15 - 11:30 Predicting hue scaling for abnormal color vision with perceptual models of color deficientvision …………………………………………………………………………… 35

Vasco MN de Almeida, Jorge LA Santos, João MM Linhares, Catarina AR João, Sérgio MC Nascimento

11:30 - 11:45 The use of the Colour Assessment and Diagnosis (CAD) test in congenital achromatopsia …………………………………………………………………………… 36

Emily J Patterson, Christopher S Langlo, Joseph Carroll

11:45 - 12:00 General discussion12:00 - 12:30 Group photo12:30 - 20:00 Lunch & Excursion

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MONDAY 6th JULY


COLOUR COGNITION 1Chair: Marina Bloj, Eiji Kimura

09:00 - 09:15 Remembering object colours …………………………………………………………… 38 Marina Bloj, David Weiss, Karl R Gegenfurtner

09:15 - 09:30 The biological basis of categorical distinctions in infant hue memory and a similaritytocommonalitiesintheworld’scolourlexicons. ……………………… 39

Anna Franklin, Alice E Skelton, Gemma Catchpole

09:30 - 09:45 Categorical color clusters of Japanese color lexicon ……………………………… 40 Ichiro Kuriki, Yumiko Muto, Kazuho Fukuda, Rumi Tokunaga, Delwin T Lindsey, Angela

M Brown, Keiji Uchikawa, Satoshi Shioiri

09:45 - 10:00 Colour symbolism and associations in a UK population ………………………… 41 David L Bimler, Christina Levanzin, Louise Heath, Nikki Amos, Valérie Bonnardel

10:00 - 10:15 Gender difference in colour preference: A cross-cultural study ………………… 42 Valerie Bonnardel, Christian Stenz, Vonnik Hertig, Nathalie Junod-Ponsard, David L

Bimler


COLOUR COGNITION 2Chair: Steven K Shevell, Yoko Mizokami

10:45 - 11:00 Resolution of ambiguous neural representations of color in mid-level vision … 43 Steven K Shevell, Wei Wang, Jens Christiansen

11:00 - 11:15 Accurate estimation of the mean hue of rapidly presented multi-hue ensembles ………………………………………………………………………………………………… 44

John J Maule, Anna Franklin

11:15 - 11:30 Averaging across qualitatively different categories ………………………………… 45 Jacquelyn Webster, Michael A Webster

11:30 - 11:45 Preferred chromatic composition of unfamiliar paintings is similar to original ………………………………………………………………………………………………… 46 Sérgio MC Nascimento, João MM Linhares, Catarina AR João, Cristina Montagner,

Maria J Melo, Márcia Vilarigues, Maria H Freitas, Catarina Alfaro, Ana Bailão, Kinjiro Amano

11:45 - 12:00 Colour terms affect detection of colour and colour-associated objects suppressed from visual awareness …………………………………………………… 47

Lewis Forder, Olivia Taylor, Helen Mankin, Ryan Scott, Anna Franklin

12:00 - 13:30 Lunch

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INVITED TALK 3Chair: Kowa Koida

13:30 - 14:15 How are the rays coloured in the brain? ……………………………………………… 48 Hidehiko Komatsu

14:15 - 15:15 Poster 215:15 - 15:45 Coffee break15:45 - 16:30 Poster 2

COLOUR INDUCTION & CONSTANCYChair: Hannah E Smithson, Kazuho Fukuda

16:30 - 16:45 Spatialandtemporalinfluencesonbrownandyellow …………………………… 49 Steven L Buck, Takuma Morimoto, Tanner DeLawyer, Brooke Stoehr, Andrew Shelton

16:45 - 17:00 Dichoptic perception of brown ………………………………………………………… 50 Tanner DeLawyer, Hohjin Im, Cody Smith, Steven L Buck

17:00 - 17:15 Effects of lateral interactions and adaptation on color and brightness induction………………………………………………………………………………………………… 51

Qasim Zaidi, Romain Bachy

17:15 - 17:30 Twodistincttypesofcolorspreadinginflanktransparencydisplays ………… 52 Eiji Kimura

17:30 - 17:45 Ahintofglossissufficientforperceptualdiscriminationofchangesinreflectanceorillumination ……………………………………………………………… 53

Hannah E Smithson, Rob J Lee

17:45 - 19:00 Transport time19:00 - 21:00 Banquet

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TUESDAY 7th JULY


VARIABILITY IN COLOUR VISIONChair: Kenneth Knoblauch, Shigeki Nakauchi

09:00 - 09:15 Individual differences of macular pigment density and L/M cone ratio of Japanese …………………………………………………………………………………… 55

Yasuki Yamauchi, Yuki Kawashima, Keisuke Yatsu, Takehiro Nagai

09:15 - 09:30 Symmetry between S-cone increment and decrement spatial acuity is associated with better M-, but not L-cone increment acuity …………………………………… 56

Rigmor C Baraas, Lene A Hagen, Stuart J Gilson

09:30 - 09:45 A “high-level” asymmetry in the perception of blue and yellow ………………… 57 Alissa D Winkler, Lothar Spillmann, John S Werner, Michael A Webster

09:45 - 10:00 A Bayesian analysis of individual differences in the perceived strength of the WatercolorEffect. ………………………………………………………………………… 58

Kenneth Knoblauch, Peggy Gerardin, Michel Dojat, Frédéric Devinck


CENTRAL PROCESSINGChair: Thomas Wachtler, Ichiro Kuriki

10:30 - 10:45 Binocular inputs to blue-ON and blue-OFF cells in marmost lateral geniqulate nucleus ……………………………………………………………………………………… 59

Paul R Martin, Natalie Zeater, Soon Keen Cheong, Samuel G Solomon, Alexander N Pietersen, Bogdan Dreher

10:45 - 11:00 DependencyofchromaticresponsesinV1andV2onvisualfieldeccentricityandspatial frequency: an fMRI study ……………………………………………………… 60

Barry B Lee, Dany D'Souza, Tibor Auer, Jens Frahm, Hans Strasburger

11:00 - 11:15 Is it a general law that hue discrimination is better than saturation discrimination? …………………………………………………………………………… 61

Marina Danilova, John Mollon

11:15 - 11:30 Non-cardinal color mechanisms: Stimulus size matters ………………………… 62 Karen L Gunther, Colin O Downey

11:30 - 11:45 Lateral interactions in an anisotropic population code for color predict human color induction effects …………………………………………………………………… 63

Thomas Wachtler, Christian J Kellner

11:45 - 12:45 Business meeting12:45 - 13:00 Closing

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SATURDAY 4th JULY & MONDAY 6th JULY

POSTER1. PossibleinfluenceofL/MconeratioonchromaticdetectionthresholdsusingLandMcone

noise masking …………………………………………………………………………………………… 65 Makito Sato, Keiji Uchikawa

2. Amodelforfovealandparafovealsensitivitythatcouldhelpourunderstandingaboutlight adaptation ………………………………………………………………………………………… 66

Alejandro H Gloriani, Beatriz M Matesanz, Pablo A Barrionuevo, Isabel Arranz, Luis Issolio, Santiago Mar, Juan A Aparicio

3. InvisiblenoiseintheMC-,PC,andKC-pathwaysaltersrodsignalinginthemesopicrange ………………………………………………………………………………………………………………　67 Andrew J Zele, Amithavikram R Hathibelagal, Jan Kremers, Beatrix Feigl

4. NeuralresponsetocolorcombinationsinmacaqueareaV4 …………………………………… 68 Takahisa M Sanada, Hidehiko Komatsu

5. SaccadelatencytoL-MandScontraststimuli …………………………………………………… 69 Aoi Takahashi, Satoshi Nakadomari, Ayumu Furuta, Hiroshi Horiguchi, Hiroyuki Kubo, Koichi Oda

6. Effectsofluminanceandisoluminancestimulionperceivedstabilityacrosssaccadiceyemovements: a study of the landmark effect ……………………………………………………… 70

Kazumichi Matsumiya, Masayuki Sato, Satoshi Shioiri

7. Highertemporalresolutionofisoluminanceyellow/bluecontrastthanthatofluminancecontrast at same detection threshold level ………………………………………………………… 71

Lin Shi

8. Thepossibilityofrevealingchromatatopicmapsinthehumanusing7TfMRI ……………… 72 Chris Racey, Weitske van der Zwaag, Ryota Kanai, Alex R Wade, Anna Franklin

9. DifferencesinfMRIresponsestocardinalanduniquehuesinhumanvisualcortex ……… 73 Wakiko Maemura, Ichiro Kuriki, Kazumichi Matsumiya, Satoshi Shioiri

10.Spatialpropertyofluminoussignalsuppressionbypresentationofcolouredpatches … 74 Ippei Negishi, Keizo Shinomori

11. Corticalresponsetocategoricalcolorperceptionininfantsinvestigatedbynear-infraredspectroscopy …………………………………………………………………………………………… 75

Jiale Yang, So Kanazawa, Masami K Yamaguchi, Ichiro Kuriki

12.CategoricalcolornaminginJapanesewithouttheconstraintofmonolexemiccolorterms ……………………………………………………………………………………………………………… 76 Kazuho Fukuda, Yumiko Muto, Keiji Uchikawa

13.Neuralbasesofcolorknowledgeinhumans ……………………………………………………… 77 Yuka Oishi, Hikaru Nagasawa, Naohiro Saito, Kyoko Suzuki

14.Infantslookingtimestohuescorrelateswithadultpreferenceandhowrepresentativethecolours are of colour terms …………………………………………………………………………… 78

Alice E Skelton, Gemma Catchpole, Luke Wassell , Anna Franklin

15.Flexiblebrightnessaveragingforheterogeneousluminancepatches ……………………… 79 Yusuke Takano, Eiji Kimura

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16.Usingmaximumlikelihoodconjointmeasurementtoestablishthecontributionsofchromaand lightness to colour judgments ………………………………………………………………… 80

Marie R Rogers, Kenneth Knoblauch, Anna Franklin

17.UniquehuecorrectionappliedtothecolorrenderingofLEDlightsources ………………… 81 Pedro J Pardo, Eduardo M Cordero, Maria Isabel Suero, Angel Luis Perez

18.Perceptualfluorescenceexplainedbyoptimalcolordependsonpre-assumedilluminantspectrum ………………………………………………………………………………………………… 82

Ryuji Katagiri, Shigeki Nakauchi

19.Standarddeviationofluminancedistributionofanimagesignificantlyrelatestogoldappearance ……………………………………………………………………………………………… 83

Tomohisa Matsumoto, Kazuho Fukuda, Keiji Uchikawa

20.Analysisofthematerialperceptionofgoldusingrealobjects ………………………………… 84 Qi Zheng, Keita Hirai, Katsuyoshi Hoshino, Takahiko Horiuchi

21.Comparativeanalysisofsubjectiveandobjectiveclinicalpterygiumgradingbasedonitsredness appearance …………………………………………………………………………………… 85

Mohd Radzi Hilmi, Mohd Zulfaezal Che Azemin, Khairidzan Mohd Kamal

22.Detectioninchromaticnoiseandvisualfatigue ………………………………………………… 86 SergejsFomins,GuntaKrūmiņa

23.Colorcontingentaftereffectswithspatialattentionshifts ……………………………………… 87 Hiromi Yura, Keiji Uchikawa

24.Radialphantommotionaftereffectsbytheisoluminatstimulus ……………………………… 88 Tatsuya Yoshizawa, Toshihito Azumi

25.Dissociationofneutralchromaticpointsforcolordiscriminationandcolorappearance under incomplete chromatic adaptation …………………………………………………………… 89 Tomoharu Sato, Takehiro Nagai, Ichiro Kuriki, Shigeki Nakauchi

26.Contrastadaptationtoluminanceandbrightnessmodulations ……………………………… 90 Takehiro Nagai, Kazuki Nakayama, Yuki Kawashima, Yasuki Yamauchi

27.Illuminantestimationusingtheoptimal-colorhypothesisoncolorconstancy …………… 91 Takahiro Kusuyama, Kazuho Fukuda, Keiji Uchikawa

28.Influenceofthenumberofsurroundingcolorsonluminance-balancebasedestimation of illuminant ……………………………………………………………………………………………… 92 Takuma Morimoto, Kazuho Fukuda, Keiji Uchikawa

29.Theinfluenceofchromaticsurroundsonperceptionofbrown ……………………………… 93 Luis Garcia, Tanner DeLawyer, Steven Buck

30.Stimulussizedependenceofhuechangesinducedbychromaticsurrounds ……………… 94 Christian J Kellner, Thomas Wachtler

31.Theeffectsofcontouradaptationonthewatercolorillusion …………………………………… 95 Andrew J Coia, Michael A Crognale

32.TestilluminantlocationwithrespecttoPlanckianLocusaffectschromaticityshiftsofrealMunsell chips …………………………………………………………………………………………… 96

Ausra Daugirdiene, Janus Kulikowski, Ian Murray James , Jeremiah Kelly

33.Colorfulnessperceptionofnaturalimagesadjustingtohaze ………………………………… 97 Yuki Takahashi, Yoko Mizokami, Hirohisa Yaguchi

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34.Influenceofageoncontrastthresholddetectionforurbanlampswithdifferentspectraldistribution in the mesopic range …………………………………………………………………… 98

Isabel Arranz, Matesanz M Beatriz, Issolio Luis, Silva Barbara, Colombo M Elisa, Menéndez A José, Mar Santiago, Aparicio A Juan

35.Adjustingtoanaginglens …………………………………………………………………………… 99 Katherine EM Tregillus, John S Werner, Michael A Webster

36.AniPadapplicationtotestcoloursensitivity ……………………………………………………… 100 Lakshmi Bodduluri, Mei-Ying Boon, Stephen John Dain

37.Steady-statevisualevokedpotentialsreflectingcolordiscriminationabilityofindividuals. ……………………………………………………………………………………………… 101

Hideaki Hirose, Shigeki Nakauchi

38.Consistencyofcolourrepresentationinsmartphones ………………………………………… 102 Stephen J Dain, Benjamin Kwan, Leslie Wong

39.Clarifyingcolorcategoryborderaccordingtocolorvision …………………………………… 103 Yasuyo G Ichihara

40.Experiencesandconsciousnessofteachersaboutcongenitalcolorvisiondeficienciesof students ……………………………………………………………………………………………… 104

Nobuyuki Nagai

41.Colourpreferenceinred-greendichromats ……………………………………………………… 105 Leticia Álvaro, Humberto Moreira, Julio Lillo, Anna Franklin

42.Benchmarktoselectapreferablecolorenhancementforanindividualobserver ………… 106 Taku Goto, Tomoharu Ishikawa, Kazunori Asada, Miyoshi Ayama

43.Thestroopeffect,colorvisiondeficiencies,andmildhypoxia ………………………………… 107 Jeffery K Hovis, Nelda J Milburn, Thomas E Nesthus

44.Colorappearanceofredprintinginkwithvariousspectralreflectancesforcolorvisiondeficiency ………………………………………………………………………………………… 108

Masami Shishikura, Terumi Kato, Yoko Mizokami, Shinichiro Taniguchi, Tomomi Takeshita, Fumiko Goto, Hirohisa Yaguchi

45.Preliminaryreportofcolour-blindnessinthePunjab,Pakistan ……………………………… 109 Muhammad S Akhtar, Asif Hanif, Muhammad Aslamkhan

46.Colornamingpropertiesandcolorimpressionofsubjectswithdeficientcolor-visionatdifferent brightness levels …………………………………………………………………………… 110

Keiko Sato, Hironori Takimoto, Yasue Mitsukura

* Poster will be on display throughout the symposium.Poster presentation assignments: Odd-numbered posters on July 4 and even-numbered posters on July 6.

FRIDAY

2

Two spectral lights are described as complementary with respect to a given white if, when they are additively mixed, they match that white. Many handbooks of colorimetry or visual science give a standard table of wavelengths that are complementary with respect to the standard Daylight Illuminant D65. Curiously, however, there do not appear to have been any direct empirical determinations of complementary wavelengths for almost a century. The values tabulated in textbooks are derived by calculation from the CIE (1931) Observer.

The purpose of the present paper is to draw attention to the very different set of complementary wavelengths that are predicted by the physiological fundamentals recently introduced by Technical Committee 1-36 of the CIE. For wavelengths in the range 400-450 nm, the complementary wavelengths are similar to those predicted by the CIE (1931) Observer (or by the Judd Observer on which the Smith-Pokorny cone fundamentals are based.) But above 450 nm, the complementaries derived from the new Observer increasingly diverge from those derived from the 1931 Observer. For the new Observer the complementary of 490 nm falls at 634 nm, whereas the value for the 1931 Observer is close to 600 nm. The wavelengths 491–493 nm have complementaries for the 1931 Observer but no complementaries for the new Observer. The new Observer was designed to be compatible with the 2-deg colour matching functions of Stiles and Burch; and the latter indeed predict complementary wavelengths that are very different from those tabulated in textbooks.

A modern empirical determination of complementary wavelengths would be valuable. The largest technical difficulty would lie in the exact simulation of D65 (or other achromatic standard); but this difficulty could be side-stepped by a transitivity test that used three sets of predicted complementaries.

Corresponding author: [email protected] of Experimental Psychology, University of Cambridge, UK

John Mollon

Do we need a new determination of complementary wavelengths?

Time: 13:45 - 14:00Session: Comparative colour vision & physiology

FRIDAY 3 JULY

COMPARATIVE COLOUR VISION & PHYSIOLOGY

3

Color is a manipulatable attribute independent to the shape and luminance. Some neurophysiological and psychological studies support the independence of color signals; however, those examinations were limited in stimulus range due to the display gamut. Here, I examined color selective response and luminance dependency of the neuron in the anterior inferior temporal cortex of the macaque monkey using a custom-made, high-dynamic-range display. Stimuli were an equiluminant uniform surface with its color systematically distributed from the RGB gamut of the display. Luminance varied from 1 to 500 cd/m2. Single unit recordings were made of the awake monkey and stimuli were presented while the animal was fixating. Besides the known type of cells showing invariant color selectivity across the 1:500 luminance range, I found that color-selective cells showed novel luminance selectivity, which prefers specific luminance. Those cells showed similar color selectivity to the colored object which has luminance shades. This color selectivity indicates that both color and luminance were jointly coded and might form the invariant color cognition of colored objects.

Corresponding author: [email protected] Interdisciplinary Research Institute, Toyohashi University of Technology, Japan

Kowa Koida

Color and luminance selectivity of neurons in the monkey inferior temporal cortex


FRIDAY 3 JULY

4

Purpose: Recently, we have described that L- and M-cone driven ERG responses depend differently on stimulus size when they feed into two distinct (putatively parvo- and magnocellular) post-receptoral pathways. The purpose of the present study was to measure rod-driven ERG responses as a function of temporal frequency and stimulus size and to compare the results with cone-driven ERGs at identical conditions.Methods: ERG responses were measured from 5 subjects with normal color vision using DTL electrodes. Responses were measured to stimuli that were generated by a four primary stimulator and that isolated the responses of the rods, the L-cones or the M-cones using triple silent substitution. Responses were measured at 9 different temporal frequencies between 2 and 60 Hz. The measurements were performed using full field stimuli and using circular stimuli with 40°, 50°, 60° and 70° diameter. Mean luminance was 284 cd/m² and the pupil was dilated. The stimuli were therefore photopic.Results: The results of recordings confirm our previous conclusions that the L- and M-cone driven signals are processed by two different post-receptoral mechanisms: At intermediate temporal frequencies of about 12 Hz, the ERG responses were governed by a mechanism with very similar L- and M-cone driven response amplitudes on which the employed stimulus size hardly influenced the responses. High temporal frequency (> 30 Hz) responses were determined by a mechanism with stronger L- than M-cone input. These responses amplitudes strongly decreased with decreasing stimulus size. Thus, cone-driven response amplitudes either decreased or remained constant with decreasing stimulus size. The amplitudes of rod-driven responses to stimulus frequencies below 16 Hz strongly increased when the stimulus size was decreased from full field to a 70° diameter. Full-field rod-driven responses were clearly measurable at high temporal frequencies (> 40 Hz). These high frequency rod-driven responses were not present when circular stimuli were used.Discussion: The rod-driven ERG responses displayed substantially different characteristics than cone-driven ERGs, strongly indicating that the stimuli appropriately isolated the response of a single photoreceptor type. The increase in rod-driven responses with a decreasing stimulus size for frequencies below 20 Hz is probably related to stimulation of the far peripheral retina by stray light. The rod-driven responses show different characteristics for frequencies below and above about 20 Hz. Rod driven responses measured at photopic conditions and at high temporal frequencies possibly employ cone pathways via rod-cone connections.

Corresponding author: [email protected]. of Ophthalmology, University Hospital Erlangen, Germany

Jan Kremers, Avinash Aher, Tina Tsai

The effects of stimulus size on rod and cone driven ERG responses


FRIDAY 3 JULY

5

Purpose: Small spectral separation between mouse rod and M-cone pigments limit the dynamic range of silent substitution isolation of either photoreceptor type. We tested the potential to achieve a higher degree of separate cone or rod modulation and hence, more robust rod- and cone-specific electroretinograms (ERGs) with this method in a newly developed transgenic mouse with human L- in place of native M-opsin (Opn1lwLIAIS or LIAIS). Methods: Rod- or cone-isolating sinusoidal flicker ERG stimuli were created using a six primary stimulator (Q450 SC, Roland Consult) and the double silent substitution technique. Under each condition, ERGs were measured at temporal frequencies of 4–30 Hz for three mean luminances (13, 39 and 130 cd/m2) and photoreceptor contrasts (cone 20, 40 and 55%, rod 25, 50 and 75%) in ketamine:xylazine sedated wildtype (WT; n = 4) and LIAIS mice (n = 15). Comparison with WT mice was made at 39 cd/m2 and the highest achievable contrast in each variant. ERGs were Fourier analysed to extract amplitudes and phases of the fundamental component. A slope parameter of phase delay was obtained from describing each frequency-phase relationship with a linear regression. Results: Robust rod- and cone-specific functions were obtained in LIAIS mice using silent substitution. As expected, significantly poorer signals were yielded in WT mice (~10x smaller), as only 5% contrast could be achieved. Despite this, WT rod- and cone-ERG response behaviours as a function of frequency were similar to LIAIS. Further characterisation of LIAIS response properties showed comparable effects of luminance and contrast on separate cone- and rod-driven amplitudes at 39 and 130 cd/m2 (p>0.06), but not at 13 cd/m2 (p≤0.01). Otherwise, rod and cone frequency-response and phase behaviours were surprisingly alike under all stimulus settings, apart for a consistent 180° phase shift between them. Their amplitudes (cones 2.5x rods) showed low-pass characteristics that gradually decreased with increasing temporal frequency, and phase lags (cones 36–42 ms, rods 33–47 ms delay, all p>0.01) that were negatively correlated with frequency increase in a linear manner. Conclusions: The physiological properties of cones were normal in LIAIS, complementing past anatomical validations. Apparent opponent processing of rod and cone signals may represent the basis of some type of colour vision in mice. This mutant allows a more fruitful use of silent substitution to study separate photoreceptor-driven signals in the mouse. Cross-breeding the LIAIS line with mouse models of disorders that affect colour vision may also grant a more detailed examination of photoreceptor pathophysiology underlying the disease.

Corresponding author: [email protected]

1Department of Ophthalmology, University Hospital Erlangen, Germany2Department of Biology, Animal Physiology, FAU Erlangen-Nuremberg, Germany3Vision Sciences, University of Washington, Seattle, Washington, USA

Tina Tsai1,2, Jan Kremers1, Jenny Atorf1,2, Maureen Neitz3, Jay Neitz3

Electrophysiological responses mediated by single photoreceptor types in mice with human L-opsin


FRIDAY 3 JULY

6

While humans and most other vertebrates have one single class of rod photoreceptors and are color-blind at night, amphibians have two distinct spectral classes of rods: the “red” rods, with peak sensitivity at around 500 nm, and the “green” rods, only found in this group, with peak sensitivity at around 430 nm. This unique feature has long ago raised the question of whether amphibians can see colours at night, even at light levels that are too low to allow for reliable cones signals and cone-based colour discrimination. However, no confirmation of this ability has been reported in behavioural tests with a proper control of achromatic cues, which are the only reliable demonstration of colour vision in any condition.We developed a protocol for testing colour vision at photopic, mesopic and scotopic light levels using two European anurans, Bufo bufo and Rana temporaria, as model species. We use a two-choice test, in which the animals are shown moving, prey-sized stimuli, one green and one blue in each trial; choice of green is rewarded with a real prey item. Several combinations of blue and green shades varying in intensities, contrasts and position are used to exclude achromatic cues and ensure that the choice is based solely on colour.With these experiments we found that Bufo bufo can make colour-based choices at light intensities as low as 10-4 cd/m2, around 100 times lower than the threshold for human colour vision and 10 times lower than the lowest cone-based colour vision reported for any vertebrate – a nocturnal gecko whose retina has only highly-sensitive cones. On the other hand, we could also observe that chromatic and achromatic cues have different relevance for Bufo and Rana. Our results support the hypothesis of a rod-based dichromatic visual system in Amphibians, and provide a basis for more studies on the physiological and ecological aspects of the switch from cone- to rod-based colour vision in response to changes in the light environment.

Corresponding author: [email protected] of Biology, Lund University, Sweden

Carola AM Yovanovich, Almut Kelber

Behavioural evidence of scotopic colour vision in amphibians


FRIDAY 3 JULY

7

In order to achieve perceptual stability across saccadic eye movements, the visual system requires a remapping process in which the positions in the new retinal image are associated with the previous retinal image across a saccade. This mechanism still remains unknown. Displacement of a visual target during a saccadic eye movement is normally detected only at a high threshold. A study has reported that blanking the target for 50–300 msec after a saccade restores sensitivity to the displacement (Deubel, et al., 1996). This is called ‘blanking effect’. We investigated the effects with luminance and isoluminance stimuli. In the first experiment, we varied the luminance contrast of target stimuli, and found that the strength of the blanking effect increased with luminance contrast. In the second experiment, we used a red-green isoluminant target, and found no blanking effect. These results suggest that transient signals are critical to generate the blanking effect.


1Tohoku University, Japan2University of Kitakyushu, Japan

Satoshi Shioiri1, Kazumichi Matsumiya1, Masayuki Sato2

Effects of luminance and isoluminance stimuli on perceived stability across saccadic eye movements: a study of the blanking effect

Time: 15:30 - 15:45Session: Chromatic mechanisms 1

FRIDAY 3 JULY

CHROMATIC MECHANISMS 1

8

We have shown that M-cone increments elicit electroretinograms (ERGs) resembling those to L-cone (and luminance) decrements, implying significant post-receptoral (opponent) influence. Here we sought a perceptual correlate of this surprising effect.

In a 2AFC paradigm, a constant background was provided in a ganzfeld with a 4-primary LED system. A stimulus comprised an 11% increase in either M- or L-cone activation for 400ms, using triple silent substitution to calculate the required change in red, green, amber and blue luminance. It also randomly contained one of 15 levels of additional luminance bias (0.65 to 1.35 times each computed luminance). There were 10 repeats. The response was ‘brighter’ or ‘dimmer’ compared with the background. The proportion of pure cone-isolating stimuli (when bias = 1.0) which were seen as brighter was derived from the psychometric function (% brighter vs bias). Full fields, disks with diameter 15 to 50° and 4 equal cone-catch quarter annuli (outer diameters 10, 20, 30 and 40°) were tested.

Perception of the L-increment stimulus was veridical (brighter), but M-increments were generally perceived as dimmer. As field size reduced, the L:M difference became smaller. The three largest annuli showed the same inversion effect. With the 10° annulus, M-onsets were more similar to L-onsets.

The results reflect our ERG studies: M-cone increments are indeed perceived as a brightness decrease. The equal cone catch data tell us that the slight dependence on field size is not eccentricity or stimulus area dependent. Our key data exclude the central retina because of the possible influence of macular pigment (MP) with small centrally fixated targets. To allow for this a topographic correction would need to be made to the silent sub calculations. It is likely that MP influenced the 10° annular data. We confirm that the L/M inversion is not an ERG epiphenomenon, which leads us to speculate about early retinal input into brightness perception.


1Manchester Royal Eye Hospital, UK2Bradford University, UK3University Hospital Erlangen, Germany4University of Manchester, UK

Neil RA Parry1,2,4, Declan J McKeefry2, Jan Kremers2,3, Ian J Murray4

A dim view of M-cone increments


FRIDAY 3 JULY

9

Our recent psychophysical work reveals different red-green balance points when long-wavelength stimuli appear dark in a bright achromatic context, than when the same physical stimuli appear bright in a dark context. Dark stimuli look greener; bright stimuli look redder. This cannot be explained by simultaneous contrast and suggests a difference in L- and M-cone signal weights in processing of dark and bright stimuli: dark stimuli look greener because of relatively stronger weighting of M-cone signals. The red/green shift might arise from adaptation to regularities in the environment. Past work shows that L/M weights shift with long-term adaptation both under experimental conditions and naturally over the lifespan. Perhaps long-term adaptation of L/M weights occurs independently for bright and dark stimuli, driven by luminance-dependent differences in chromatic content. Thus, in the natural world, an abundance of L-cone stimulation in dark regions, or at lower luminances, might be compensated by stronger weighting of M-cone signals than in bright portions, or at higher luminances. We examine what luminance-chromaticity interactions exist within natural scenes and how these change on average over the day and year. So far, our analyses show that there are indeed some regularities in the natural world that could support luminance-dependent chromatic adaptation in the direction consistent with the observed psychophysical shift of red-green balance for stimuli that appear bright and dark. Analysis of 238 natural scenes from calibrated databases reveals that bright clear sky is a strong and ubiquitous driver of the predicted interaction. On average, pixels in the most luminous quartile were shifted towards smaller L/M ratio compared to those in the least luminous quartile. Circadian variation of daylight also commonly shows this luminance-chromaticity interaction. Analyses continue, making use of contrast computations and physiological receptive-field filters.

Corresponding author: [email protected] of Washington, USA

Joris Vincent, Alex Kale, Steven L Buck

Luminance-dependent long-term chromatic adaptation


FRIDAY 3 JULY

10

We measured color discrimination at eight locations in the MacLeod-Boynton chromaticity diagram using 3 methods: four-alternative forced choice, bipartite matching, and delayed matching to a reference. By all methods, color discrimination is about twice as bad, on average, along the negative (blue-yellow) diagonal of the MacLeod-Boynton chromaticity diagram than in the orthogonal direction.

Analysis of hyperspectral images of natural scenes reveals that the distributions of chromaticities in natural scenes are elongated along the negative diagonal of the MacLeod-Boynton chromaticity diagram, again by about a factor of 2. Our hypothesis is that the color discrimination results reveal the action of chromatic mechanisms tuned to optimally represent the ranges of chromaticities that exist in natural scenes along each chromatic axis.

However, some degree of negative correlation between S/(L+M) and L/(L+M) is expected given the positions of the cone sensitivity functions: as S increases, L tends to decrease and vice versa. To account for this we created various sets of idealizations of natural spectra, calculated their chromaticities, and quantified the elongations of the distributions of chromaticities along the negative diagonal of the MacLeod-Boynton chromaticity diagram. We found elongations ranging from 1.1 to 1.8, the magnitude depending critically on the constraints applied to create the sets of artificial spectra.

In conclusion, an optimal nonlinear encoding model of colour vision can account for performance in colour discrimination. The positions of the cone sensitivity functions can account partly but not fully for the skewed distributions of chromaticities in natural scenes.


1School of Psychology, University of Sussex, UK2Department of Psychology, UC San Diego, USA

Jenny M Bosten1,2, Donald IA MacLeod2

Color discrimination, cones and natural scene statistics


FRIDAY 3 JULY

11

Flower-visiting butterflies have color vision, including some sophisticated aspects such as color constancy and simultaneous color contrast. Unlike the trichromatic retinas of humans (blue, green and red cones (plus rods)) and honeybees (UV, blue and green cells), the compound eyes of butterflies are typically furnished with six or more photoreceptor types with distinct spectral sensitivities. We found that the eyes of the Japanese yellow swallowtail, Papilio xuthus, contain UV, violet, blue, green, red and broad-band receptors, with each ommatidium housing nine photoreceptor cells in one of three fixed combinations. This makes the Papilio eye a patchwork of three types of spectrally heterogeneous ommatidia. How do Papilio use their complex retina to see flowers? First, we measured their wavelength discrimination ability by recording the sensitivity of feeding responses toward monochromatic lights, and identified the set of receptors involved in the task. The behavioral data indicate that Papilio can discriminate 1 nm difference at least in three wavelength regions, which appears even better than in humans. Analysis of the data using the receptor-noise limited color opponency model indicated that their vision is tetrachromatic based on UV, blue, green and red receptors.

Corresponding author: [email protected] Graduate University for Advanced Sciences (SOKENDAI), Japan

Kentaro Arikawa

Color vision in butterflies

Time: 16:45 - 17:30Session: Invited talk 1

FRIDAY 3 JULY

INVITED TALK 1

SATURDAY

13

Melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are important for several sub-conscious non-image-forming functions, such as circadian photoentrainment and the pupil light reflex. However, ipRGCs also project to the lateral geniculate nucleus (LGN) that relays retinal visual information to the visual cortex, suggesting that melanopsin activation may contribute to conscious visual perception. To study whether melanopsin activation contributes to human color perception, we used a hue scaling method in a lab-developed five-primary photostimulator, which can control the excitations of rods, S-, M-, L-cones and melanopsin-mediated ipRGCs at a constant light level (Cao, Nicandro & Barrionuevo, Journal of Vision, 2015, 15(1):27, 1-13). The stimulus field was a 30° circular field with the central 10.5° blocked to minimize the potential artifact of spectrally selective macular pigment absorption. The perceived hues and saturation levels were rated for a light with melanopsin signals modulated in a square-wave (0.5 Hz, 38% Weber contrast at 200, 2,000 and 20,000Td), while keeping rod and cone excitations constant [L/(L+M) = 0.764, S/(L+M) = 0.104, R/(L+M) = 0.320]. At the baseline melanopsin activation level, the light was perceived as orange (a combination of red and yellow), and the perceived yellowness (relative to redness) increased from 200 Td to 2000 Td. A 38% increase in melanopsin activation levels shifted the perceived hue toward more yellowness (~5% increase relative to the baseline at 200 Td or ~30% increase at 2,000 Td and 20,000 Td) and less redness (~5% decrease relative to the baseline at 200 Td or ~30% decrease at 2,000 Td and 20,000 Td), while the perceived saturation remained unchanged. Therefore, melanopsin activation alone can substantially contribute to color perception by signaling yellowness and greenness.

Corresponding author: [email protected] of Ophthalmology and Visual Sciences, University of Illinois at Chicago, USA

Dingcai Cao, Pablo A Barrionuevo

Melanopsin-based color percepts


SATURDAY 4 JULY

CHROMATIC MECHANISMS 2

14

Natural lights have a broad and complex spectral radiant power distribution that stimulate rods, cones and the third class of photoreceptor, intrinsically photoreceptive retinal ganglion cells (ipRGCs). Growing evidence indicates that ipRGCs play an important functional role in conventional image-forming pathway as well as in non-image forming pathway, along with the classical photoreceptors. Although both cone- and ipRGC-mediated signals contribute to image-forming pathway, it is still unclear how these signals are summed and contribute to the image-forming functions. The aim of this study is to determine relative weights of cones and ipRGCs for contrast detection mechanism.A four-primary illumination system that enables independent stimulation of each photoreceptor class (Tsujimura et al., 2010, Proceedings of the Royal Society B-Biological Sciences, 277, 2485-2492) was used to present the following two types of test stimuli: one varying L-, M- and S-cone stimulation only without change in stimulation of ipRGCs (LMS cone stimulus) and another varying ipRGC stimulation only without change in stimulation of L, M and S cones (ipRGC stimulus). Test stimuli were a mixture of the cone and ipRGC stimuli with variable ratios. The contrast threshold for flicker detection to temporally modulated sinusoidal gratings was measured. Threshold contours plotted in cone, ipRGC contrast planes (LMS, ipRGC) reveal relative weights of cone- and ipRGC- mediated signals for the flicker detection mechanism.It was found that the threshold contour at low temporal frequency below 5 Hz had a positive slope, indicating that there is a negative interaction of cone and ipRGC signals for contrast detection. On the other hand, the slopes of the threshold contour increased as temporal frequency increased and were almost parallel to the vertical axis at frequency above 10 Hz, indicating that cone signals solely determined the contrast thresholds. These results suggest that ipRGCs play an important role in achromatic vision at low temporal frequency.


1Department of Information Science and Biomedical Engineering, Kagoshima University, Kagoshima Japan2Faculty of Environment and Information Sciences, Yokohama National University, Yokohama Japan

Sei-ichi Tsujimura1, Katsunori Okajima2

Relative weights of cone and melanopsin cells for the flicker detection mechanism


SATURDAY 4 JULY

15

Purpose: to establish whether physical fatigue affects colour vision.

Methods: 30 healthy participants were included in the study, 15 men and 15 women, age 25.3±4.4 years. They were all professional or top recreational athletes. Their colour vision was normal (evaluated with the Ishihara, HRR and Mollon Refin Minimalist (MRM) tests). They were exhausted using the Wingate test (WT). Physical fatigue was determined by blood lactate level before WT and 1, 3, 5, 7 and 10 minutes after. Colour vision was evaluated using the HRR and MRM tests before WT and 7, 10 and 30 minutes after.

Results: The average lactate level before WT was 1.3±0.3, after 1 min 3.4±1.0, after 3 min 8.8±1.4, after 5 min 9.7±1.4, after 7 min 9.9±1.4 and after 10 min 9.5±1.5 mmol/l. All the participants showed normal colour vision in all three axes before the WT. 7 minutes after WT 2/30 (6%) showed affected colour vision in the protan axis and 25/30 (83%) in the tritan axis; however, all the participants showed normal colour vision in the deutan axis. 10 and 30 minutes after WT all the participants showed normal colour vision in deutan and protan axes, whereas 12/30 (40%) and 8/30 (26%), respectively, showed affected colour vision in the tritan axis. A gender difference was observed in colour vision improvement. 30 minutes after WT colour vision was still affected in 5 women and in 3 men.

Conclusions: The study showed that intense physical effort affects colour vision to a certain extent. The tritan axis is predominantly affected. In the great majority of participants colour vision normalised in 30 minutes; however, the recovery was faster in men than in women.


1Eye Clinic, University Medical Centre, Ljubljana, Slovenia2University of Ljubljana, Faculty of Sport, Slovenia

Manca Tekavcic Pompe1, Bor Tekavcic2, Mirjam Lasan2, Radoje Milic2

Does physical fatigue affect colour vision?


SATURDAY 4 JULY

16

Purpose. Previous studies have shown that chromatic discrimination thresholds across the life span are characterised by a dipper function that has its minimum at 20-30 years; after this age thresholds tend to rise due to age-related ocular and neuronal changes. However, it is unclear why thresholds should be elevated in the paediatric age range.In this study we tested psychophysically if the elevated discrimination thresholds of a paediatric population reflect a real anatomical and/or functional visual development; or if they are biased by the difficulty in performing the discrimination task, and the attentional resources required to execute the test. Methods. We compared paediatric performance at two chromatic discrimination tests: the Universal Colour Discrimination Test (UCDT), and the Fansworth-Munsell 100 Hue Test (FM100HT). The UCDT used a simple 2-alternative-forced-choice task to measure the minimum saturation required to discriminate the chromatic target from its achromatic background. Saturation thresholds were measured near the protan, deutan, and tritan confusion lines. Each threshold took about 2 minutes and was repeated twice for a measure of reliability. The FM100HT required the observer to sort a large number of caps according to their hue, and on average it took about 20 minutes to complete the test. The two tests were run on the same day and in random order.We tested a population of 56 paediatric observers: 18 aged 5-6 years, 20 aged 9-10 years and 18 aged 13-14 years; all had normal colour vision, as assessed by either the Ishihara or the HRR plates. Our control group consisted of 18 adult observers aged 18-23 years; all had normal colour vision.Results. Expectedly, we found that the mean total error scores measured with the FM100HT dramatically varied with age. Surprisingly, chromatic discrimination thresholds measured with the UCDT were approximately constant across age for all confusion axes. In fact, apart from a few outliers, all paediatric observers showed chromatic discrimination thresholds that fell within the normal trichromatic range.Conclusions. We found that chromatic discrimination in our paediatric population can be as good as chromatic discrimination in young adults, when assessed with a sensitive and fast colour discrimination test based on a simple task, like the UCDT.Acknowledgements. Fight for Sight, NIHR Biomedical Research Centre for Ophthalmology at Moorfields and the UCL Institute of Ophthalmology.


1Cambridge Research Systems Ltd, UK2Institute of Ophthalmology, University College London, UK3Department of Psychology, Durham University, UK

Caterina Ripamonti1,2, Sarah Kalwarowsky2, Marko Nardini2,3

Developmental changes in chromatic discrimination at 5-14 years


SATURDAY 4 JULY

17

The Rayleigh match is defined by the range of mixtures of red and green lights that appear the same as an intensity-adjustable monochromatic yellow light. The perceptual match indicates that the red/green mixture and the yellow light have evoked the same respective cone absorptions in the L- and M-cone pathways. Going beyond the existing models (e.g., He & Shevell, 1995; Thomas & Mollon, 2004; Barbur et al 2008), the Poisson noise in cone absorptions is proposed to make the matching proportion of red-green mixtures span a finite range, since any mixture in that range evokes cone absorptions that do not differ from those by a yellow light by more than the variations in the absorption noise. We derive a mathematical formula linking the match midpoint or match range with the sensitivities and numerosities of the two cones. The noise-free, exact, matching point, close to the mid-point of the matching range, depends only on the L- and M-cone sensitivities to each of the red, green, and yellow lights (these sensitivities in turn depend on the lambda max and optical densities of the cone pigments and the various pre-receptor retinal light filtering properties). Meanwhile, the matching range depends on both these cone sensitivities and the relative numerosity of the L- and M-cones. In normal trichromats, all other things being equal, the match range is smallest when the ratio (r) between L and M cone densities is r=R-1/2 with R as the ratio between the sensitivities of the L and M cones to the yellow light, i.e., when L and M cones are similarly abundant in typical cases, and as r departs from R-1/2 the match range increases, e.g., by 50% to 100% (depending on R) when one cone type is about 10 times as numerous as the other. Testing these model predictions requires either a large data set to identify the effect of one factor (e.g., cone numerosity) while averaging out the effects of the other factors (e.g., cone sensitivities), or when all factors are known in a data set.


1University College London, UK2Medical College of Wisconsin, USA

Zhaoping Li1, Joseph Carroll2

An analytical model of the influence of cone sensitivity and numerosity on the Rayleigh match


SATURDAY 4 JULY

18

The aim of this work was to assess the influence of dynamic luminance noise on the color discrimination of normal and color anomalous observers using a new color discrimination test. The stimulus was presented on a calibrated CRT display driven by a ViSaGe MKII system.

Stimulus background consisted of packed circles with variable size ranging from 1 to 4% of the screen area and random luminance from 6 to 16 cd/m2 on a uniform white area with 11cd/m2. When required, random dynamic luminance contrast noise was added at 10 Hz on each circle. A colored stimulus used to estimate the color discrimination threshold was used as target and drawn on top of the background of circles on the left or the right side of the screen. The target and the background subtended 5 and 17 degrees of viewing, respectively. The color of the target varied along 20 directions concurrent at the color of the background.

Six observers with normal color vision, 4 deuteranomalous and 2 protanomalous observers performed the test, both with static and with dynamic luminance noise in the same viewing conditions. The observer’s task was to signal the position of the target, on the left or the right side of the screen. Each observer performed three repetitions in a stair case procedure. Color discrimination thresholds were estimated and averaged across the 20 directions for static and dynamic noise on all observers.

A t-test analysis considering the 3 different types of observers was performed to compare the discrimination thresholds obtained with and without dynamic noise at each hue tested. The analysis revealed significant differences for anomalous observers (p<0.001) but not for normal observers (p>0.05).

The data estimated here seems to indicate that there is no influence of the dynamic luminance contrast noise masking on the color discrimination task performed by normal observers, but such effect might be found on anomalous observers, considering the analysis of the individual hues.


1University of Minho, Centre of Physics,Campus de Gualtar, 4710-057 Braga, Portugal2Department of Physics, University of Beira Interior, 6201-001 Covilhã, Portugal3Facultad de Psicología, Universidad Complutense de Madrid, 28883 Pozuelo de Alarcón España, Spain

João MM Linhares1, Catarina AR João1, Eva DG Silva1, Leticia Álvaro3, Jorge LA Santos2, Vasco MN Almeida2, Sérgio MC Nascimento1

Assessing the effects of dynamic luminance contrast noise masking on a color discrimination task

Time: 10:45 - 11:00Session: Colour vision deficiency

SATURDAY 4 JULY

COLOUR VISION DEFICIENCY

19

How people with colour vision impairments see the world remains imperfectly understood. In Japan, a colour vision test has been included in the compulsory physical test of schoolchildren based on the Law of School Health, which was enacted in 1958. Children who misread the Ishihara test plates were considered to be colorblind, and faced discrimination in education, employment and marriage. Color vision tests using the Ishihara test will identify congenital abnormalities, but do not give information on which colours and individual will confuse. These confusion colors, however, are precisely the thing that people in school settings, including students themselves, teachers, and students' families, want to know. The Ishihara test is a test used by medical doctors to determine congenital abnormalities, but is of little use to school nurses and teachers. We developed the Colour Mate Test (CMT) together with a color psychologist for use in schools. The CMT is meant for use by school teachers and school nurses to identify the colours an individual child will have difficulties with. The CMT consists of 5 cards, each of which has 5 coloured squares arranged in a cross configuration. Either the vertical or horizontal row contains colors of the same hue. These colors are “color mates,” which the student identifies. The CMT is not an ophthalmological test, nor is it suitable as a vocational aptitude test. Different tests are needed for those purposes. The CMT is used by teachers so that they know which colours a child has difficulty with and can test follow-up measures to avoid problems, such as avoiding those colour combinations or using means other than colour to differentiate information on maps, graphs, and other visuals. Neither the Ishihara test nor the CMT is appropriate for deciding a child's future field of work. That is something that the child and his or her family will need to think about themselves, considering various factors.

Corresponding author: [email protected] University, Japan

Masaru Miyao

Colour vision for schoolchildren


SATURDAY 4 JULY

20

Lantern tests were introduced in the transport environment as a practical means of determining whether applicants can identify signals and navigational aids. The Holmes-Wright type A (HW-A) lantern was introduced in 1982 and is currently one of the CIE recommended colour vision tests for the transport services. Although still is use, the HW-A lantern is no longer manufactured or supported. This study examines the pass rates for the HW-A when adhering to the UK Civil Aviation Authority (CAA) protocol for Class 1 medical certificate and the CIE Colour Vision Standard 2 required in occupations within maritime, rail and road transport. Over 300 colour defective subjects (226 deutans and 92 protans) were examined on the HW-A, Ishihara and the Colour Assessment and Diagnosis (CAD) test.The results show that ~ 22% of deutans pass the HW-A lantern according to these protocols. However, < 2% of protans pass. Not unexpectedly, some overlap exists in red-green (RG) thresholds measured on the CAD test among deutans that pass and deutans that fail this lantern. A threshold limit of 4 CAD units ensures that ~ 22% of deutans pass. This value also ensures that the number of deutans that pass with a threshold > than 4 equals the number of deutans that fail with a threshold ≤ 4. All deutans with a threshold less than 2.35 RG CAD units (~ 6%) pass HW-A. The HW-A lantern as recommended by the CIE and used by the CAA has provided for decades confirmatory or secondary testing to assess whether candidates with congenital colour deficiency have sufficient chromatic sensitivity to carry out colour-related tasks within selected environments. This approach has worked well in that no safety issues have emerged that can be linked directly to the 22% of deutans that pass. These results suggest that in the absence of carefully conducted studies designed to assess the use of colour signals within a specified environment, a useful practical approach is to grade applicants into two groups: those with a RG CAD threshold < 2.35 units (that can be classed as functionally normal (FN)) and those with thresholds less than ≤ 4 CAD units that can be classed as ’colour safe’ (CS), the latter being equivalent to the outcome expected using the HW-A lantern. The new CS limit is statistically equivalent to the HW-A and can in principle be introduced without the need for further studies.

Corresponding author: [email protected] Vision Research Centre, City University London, London, UK

Marisa Rodriguez Carmona, Joseph D Hickey, John L Barbur

New pass / fail threshold limits consistent with Holmes-Wright lanterns


SATURDAY 4 JULY

21

Until 2004, people who misread the Ishihara test plates could not obtain a small boat licence in Japan. The Ishihara test is not appropriate for this use, and unfairly restricts some people from operating boats. In some cases I was consulted by school counselors about junior high school students who wanted to be boat racers but failed the colour vision test, and began refusing to go to school and being violent within the family. Upon looking into this I found that in the USA and Australia anyone with a driver's licence could drive a boat. I approached the Ministry of Land, Infrastructure, Transport and Tourism and we began working at the Port of Nagoya to test the colour discrimination ability that is actually needed to operate a boat. First we tested discrimination of three colour buoys. All people who failed the Ishihara test passed this test. However, predicting that it would be difficult to differentiate between red and green lights at night, we made a test device using three colour lights: red, green, and white. This test is the closest thing to the actual circumstances and is currently used in the small boat license test. About 45,000 people take this test every year, and of them only about 150, or 0.3%, fail. These people can take another paper-based test for a daytime-only licence. For seven years we worked on a similar device for the licence for large boats and ships, using the four colours of red, green, yellow and white lights. The Ishihara test is no longer used for small boat licence tests, and we think the same is true for large boats and ships. The ability to read the Ishihara test plates is not an accurate reflection of real-life ability. The Ishihara test may also reveal genetic conditions, which is an invasion of the individual's privacy. It should also be noted that its reliability for women is very low in all cases, and as more women come to work on ships this is a real problem. We hope to soon have a practical test for large boat licences.

Corresponding author: [email protected] Ophthalmology and Neurology Clinic, Japan

Yasuyo Takayanagi

Colour sense for boat licence tests


SATURDAY 4 JULY

22

Primate colour vision is unique among vertebrates in its evolutionary history. The form of trichromacy found uniquely in primates was generated from ancestral dichromacy via allelic differentiation [(in most platyrrhines (New World monkeys) and some strepsirrhines] or gene juxtaposition [in catarrhines (Old World monkeys, apes and humans) and Alouatta (howler monkeys: a New World monkey genus)] of the L/M opsin gene. The allelic differentiation results in extensive colour vision variability in New World monkeys, where trichromats and dichromats are found in the same breeding population. Our genetic studies showed that the nucleotide variation of the L/M opsin gene exceeded that of neutral expectation in wild populations of New World monkeys and interpreted that their colour vision variation was maintained by balancing selection. We also found that the ateline New World monkeys renovated the L/M opsin polymorphism by amino acid mutations unique to atelines so that the spectral separation between the longest-wave allele and middle-wave allele is widened, while they appeared to be losing the shortest-wave allele. Howler monkeys were previously predicted to be invariant with a normal L and a normal M juxtaposed on the X chromosome, but were found to possess hybrid L/M genes with intermediate wavelength of maximal absorption (λmax) between the L and M. Contrary to the great genetic variation of the L/M opsins in New World monkeys, we showed that gibbons (lessor apes) were retained invariant with a normal L and a normal M (and thus normal trichromacy) by the action of natural selection to purge gene conversions between the two genes. On the other hand, our field behavioral studies have cast a controversy concerning the advantages of trichromatic colour vision. In foraging efficiency for fruit and figs, we have found no apparent superiority of trichromacy over dichromacy. Rather, dichromats were superior in capturing surface-dwelling insects. We found no advantage to trichromats over dichromats for fitness measures using long-term (26 years) survival and fertility data of wild capuchin monkeys. In our field observation the sniffing frequency to fruit was negatively correlated with visual contrast of fruit to mature leaves and positively correlated with the rejection frequency of fruit. We also found that odors were more honest/reliable signal than color change in some fruit species. A long-standing hypothesis is that the advantage of color vision over other senses and of trichromacy to dichromacy in primates is in long-distance detection of yellow-reddish objects against dappled mature foliage. Our colorimetric modeling also supports it, but foragers of fruit may rely on other senses for close-range assessment of individual fruits. It is still an open question if the long-distance advantage of trichromacy is the source of selection to maintain the vision variation or if the mixed presence of different color vision types confers a selective advantage to each vision type in New World monkeys. This question is relevant to understand why the normal trichromacy is maintained in catarrhines (except in humans). A deeper knowledge of the functional significance of colour vision in non-human primates will help us to understand the selective pressures acting on colour vision in our own species. Further interdisciplinary studies on genes, physiology and behaviour will provide a wealth of data for increasing our understanding of the evolution of colour vision and will generate important advances in the near future.

Corresponding author: [email protected] University of Tokyo, Japan

Shoji Kawamura

Evolutionary diversity of colour vision in primates: implications from field and genetic studies


SATURDAY 4 JULY

INVITED TALK 2

23

We report the results of a clinical study designed to quantify red / green (RG) and yellow / blue (YB) loss of chromatic sensitivity in diabetics with no retinopathy. 219 subjects were selected for the study and the principal aim was to establish the extent to which colour vision is affected in the absence of clinical signs of retinopathy. A second aim was to establish the correlation between the severity of colour vision loss and the parameters that are traditionally associated with diabetes such as body mass index (BMI), age, duration of diabetes, visual acuity (VA), daily blood-glucose level, glycated haemoglobin (HbA1c) and central retinal thickness.

The study was carried out in UAE by the Moorfields Dubai Eye Hospital and the Imperial College Diabetes Centre in Abu Dhabi. Both RG and YB colour vision was measured using the CAD test (Expert Rev. Ophthalmol. 6(4):409-420, 2011). Inclusion criteria were a best corrected visual acuity of 6/18 or better, no more than moderate maculopathy and no co-existing glaucoma. Patients had a full eye examination (including colour photography and macular OCT) and full assessment of their diabetes.

Binocular, age-corrected colour threshold limits were employed to screen for normal colour vision. Abnormal colour vision was noted in 70% of participants. The remaining 30% all had thresholds above the normal median at every age. As a subgroup these patients were therefore abnormal since age-matched normals exhibit thresholds that are distributed equally both above and below the median. The severity of colour vision loss did not correlate with duration of diabetes, age, HbA1c, BMI, visual acuity or central retinal thickness.

In spite of the absence of retinopathy, both RG and YB colour vision is abnormal in almost all the diabetics examined in the study. The severity of loss can vary from small changes to complete loss of chromatic sensitivity. These findings suggest the existence of early retinal changes in diabetes that affect specifically colour vision and occur independently of factors such as those causing microvascular changes and/ or macula edema. Neuroretinal function is therefore compromised before the onset of vascular lesions that can be detected clinically. For comparison, results of similar studies carried out in patients with age-related macular degeneration and glaucoma will also be presented.


1City University London, UK2Imperial College Diabetes Unit, UAE3 Moorfields Dubai Eye Hospital, UAE

John L Barbur1, Imran Ansari2, Chris Canning3

Loss of colour vision in diabetes

Time: 16:30 - 16:45Session: Affected colour vision

SATURDAY 4 JULY

AFFECTED COLOUR VISION

24

Congenital achromatopsia (ACHM) is an autosomal recessive signal transduction disorder in cone photoreceptors causing severe to complete loss of cone function, causing poor visual acuity, photoaversion, nystagmus and absent color vision. Clinically, ACHM is a relatively stable condition, though nystagmus often dampens with increasing age. Imaging studies have shown residual cone structure in patients with ACHM, though the stability of this residual structure is not clear. Eight human subjects with CNGB3 or CNGA3 mutations were recruited. Adaptive optics scanning light ophthalmoscopy (AOSLO) was performed on all subjects at a baseline visit and upon follow up (mean 7 months, range 6-10). Cone density was estimated from the resulting images at the center of the foveal pit (as determined by OCT), as well as 1o, 5o and 10o of visual angle away from the pit center both temporally and superiorly.

Due to nystagmus or fixation instability, not all locations could be imaged in every subject. While all subjects exhibited measurable residual cone structure, the residual cone densities were significantly below normal values. Mean cone density at baseline was 8,214 cones/mm2 at the foveal center, 5,928 at 1o, 3,071 at 5o and 2,420 at 10o temporal; the superior densities were 5,162, 3,700 and 2,225 respectively. The densities on follow up were 9,300 cones/mm2 at the foveal center, 6,214, 2,657 and 2,740 at 1o, 5o and 10o temporal and 4,888, 3,167 and 2,300 at 1o, 5o and 10o superior. There was no significant difference in density between time points (p = 0.67), with a mean difference of 117cones/mm2, which is less than previously published repeatability measurements in normal retinas.

Our data indicate that cone structure is stable over the time frame assessed here.


1Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA2The Pangere Center for Hereditary Retinal Diseases, The Chicago Lighthouse for People Who Are Blind or Visually Impaired, Chicago, IL, USA3Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI, USA4Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA5Department of Ophthalmology, University of Florida, Gainesville, FL, USA6Department of Ophthalmology and Visual Sciences, The University of Illinois at Chicago, Chicago, IL, USA

Christopher S Langlo1, Frederick Collison2, Phyllis Summerfelt3, Carol White2, Alfredo Dubra1,3,4, William Hauswirth5, Gerald Fishman2,6, Joseph Carroll1,3,4

Longitudinal measurement of cone density in congenital achromatopsia


SATURDAY 4 JULY

25

Each of the three major visual pathways, magnocelluar, parvocellular and koniocellular pathways, has subdivisions forming parallel ON and OFF systems. We have demonstrated differences between luminous and S-cone ON and OFF psychophysical impulse response functions (IRF), and now examine whether ON and OFF IRFs differ for pulses varying in L-cone stimulation.

Impulse response functions to an incremental L-cone stimulation pulse (L-cone ON flash) and a decremental L-cone stimulation pulse (L-cone OFF flash) were derived for young (20-29 years old) and old (64-85 years old) observers. Thresholds were measured for two pulses separated by interstimulus intervals from 0 to 360 msec. The pulses had a spatial Gaussian shape (+/-1 SD = 2.3 deg. diameter) and were presented as increments or decrements of L-cone stimulation on a 10 cd/m2 equal-energy-white background, having the chromaticity change on a standard protan confusion line. A spatial 4-alternative forced-choice (4AFC) method was combined with a staircase procedure. Retinal illuminance was equated individually by heterochromatic flicker photometry and using a 2.5 mm exit pupil in a Maxwellian-view optical system. Each IRF was measured five to six times, in separate sessions, for each observer. The contrast of the decremental pulse was calculated as (2*Lb - Lt)/Lb for comparison to the incremental pulse, in which Lb and Lt are the background L-cone stimulation and the pulse negative peak L-cone stimulation, respectively. Results showed that L-cone ON and OFF IRFs calculated from the threshold data revealed significant age-related changes in the response amplitude although there was no change between ON and OFF IRFs. Interestingly, there were also significant age-related changes in the time to the peak of IRFs. Additionally, OFF IRFs were significantly slower than ON IRFs in all observers.

These age-related changes in L-cone stimulation varying ON and OFF IRFs, reflecting putative properties of the parvocellular pathway, will be discussed in relation to other age-related changes in S-cone ON and OFF IRFs, reflecting properties of the koniocellular pathway and in luminance ON and OFF IRFs of the magnocellular pathway.

Supported by KAKENHI 24300085 and the National Institute on Aging (AG04048).


1Kochi University of Technology, Kochi, Japan2University of California, Davis, CA, USA

Keizo Shinomori1, John S Werner2

Age-related changes in the impulse response to L-cone ON and OFF flashes.


SATURDAY 4 JULY

26

It is widely believed that the structural and functional declines in S-cone pathways associated with normal aging are more rapid than those for M- and L-cone pathways. This would explain celebrated results by Verriest and others demonstrating that the largest age-related color discrimination losses occur for stimuli on a tritan axis. Here, we challenge convention, arguing from functional and preliminary structural data that selective S-cone losses do not cause declines in color discrimination. We show substantial declines in chromatic detection and discrimination, as well as in temporal and spatial vision tasks, that are mediated by S-cone pathways. These functional losses are not, however, unique to S-cone pathways. Finally, despite reduced photon capture by S-cones, made worse by lenticular senescence, S-cone pathways provide essential signals for the visual system to renormalize itself, slowly and possibly cortically, to maintain nearly stable color perception across the life span.

Corresponding author: [email protected] of Ophthalmology & Vision Science, University of California, Davis, USA

John S Werner

Surprising Observations about Aging Human S-Cone Pathways

Time: 17:15 - 18:30Session: Verriest Lecture

SATURDAY 4 JULY

VERRIEST LECTURE

27

The blue-black/white-gold “dress” episode was a delightful example of color bi-stability across and within observers, which exposed how little we understand about surface, material and illumination color perception. Any “illusion” that is so powerful probably has multiple causes working together. A number of proposals have been put forward, but nobody has solid evidence that explains the individual differences or the bistability, so this session will highlight aspects of color perception that different researchers think are relevant. There will be 8-10 presentations (5 minutes each) on physical information in the images, perceptual assumptions/priors, color asymmetries, attention, inferential strategies, and neural mechanisms, followed by an extended 40-50 minute discussion with the audience.


Organizer: Qasim Zaidi

Color science behind percepts of the blue-black/white-gold dress

Time: 18:30 - 20:00Session: The "dress" session (Informal)

SATURDAY 4 JULY

THE “DRESS” SESSION (INFORMAL)

SUNDAY

29

Professor Shinobu Ishihara was born in 1879 in Tokyo. He graduated from Tokyo Imperial University School of Medicine in 1905 and studied ophthalmology at the University and on abroad at the University of Jena in 1912 under Prof. Stock. He was charged in Chairman of Professor, Department of Ophthalmology, Tokyo Imperial University School of Medicine in 1923. He played a pivotal role in developing ophthalmology in Japan to teach many distinguished fellows and to make great contribution in research and clinical field. The innovation of test plates for colour blindness is one his master pieces. In 1914 he invented prototype of Ishihara Colour vision Test in Japanese with reference to Stilling’s Test, and he published the test in 1930. His test chart had so high sensitivity and specificity that the 14th World Ophthalmology Congress in 1933 recommended the test as a reliable test method as well as Stilling’s Test and Nagel’s Anomaloscope. After he retired academic position and he was granted the title of emeritus professor from the Tokyo University in 1940, he devoted his life to improve his Test Plates. He was commended the First Order of the Sacred Treasure from the government in 1961. It is my great honor to introduce his life in the memorial symposium.


1Public Interest Incorporated Foundation Isshinkai, Japan2Sawa Eye Clinic, Japan

Mitsuru Sawa1,2

Invited talk: Prof. Ishihara and Ishihara test for colour blindness

Time: 09:00 - 09:20Session: Ishihara symposium: 100th anniversary of the Ishihara pseudo–isochromatic test plates

SUNDAY 5 JULY

ISIHARA SYMPOSIUM

30

S-cone dysfunction has been reported in heterozygotes for the T190I mutation in the S-cone-opsin gene (OPN1SW) (Baraas, Hagen et al. 2012). The purpose here was to determine if a measure of S-cone spatial acuity could detect S-cone dysfunction not easily detected as a tritan deficiency by pseudo-isochromatic tests.

Four females (27–42 yrs), heterozygous for the T190I mutation, and 16 healthy colour normals (21–49 yrs; six females), were included in this study. All had normal foveal logMAR letter acuity and no observed ocular abnormalities. Colour vision was examined with HRR pseudo-isochromatic plates (4th ed., 2002) and the Cambridge Colour Test’s trivector test (CCT) under standard conditions.

Isolated S-cone and achromatic minimum angle of resolution (MAR, arcmin) were measured monocularly in the dominant eye with a Sloan E letter at 23% and 69% S-cone contrast and 90% achromatic contrast. Thresholds were measured employing a 4AFC staircase procedure. The luminance of the S-cone stimuli and background was 10 cd/m2. The Sloan E was presented at 5 deg eccentricity from a distance of 2.3 m. Fixation was verified by an eye-tracker. All observers were corrected to best logMAR letter acuity.

Two of four observers in the T1901 group made errors on plate 2 of the HRR; one had CCT tritan score >150. The other two made no errors on the HRR; one had CCT tritan score >150. T190I group had significantly poorer S-cone MAR at 69% cone contrast (15.8–25.0) than normals (8.8–16.1). Three of four in the T190I group were unable to perceive the Sloan E at 23% S-cone contrast. The fourth could perceive the stimuli but had poorer performance than the normals (34.7 versus 15.5–22.2). The T190I group’s achromatic acuity (1.8–2.5) was at least as good as the normals (2.2–3.1).

The results suggest that S-cone spatial acuity may be a robust measure of S-cone dysfunction that presents with or without a tritan deficiency if measured with pseudo-isochromatic colour vision tests.


Department of Optometry and Visual Science, Faculty of Health Sciences, Buskerud and Vestfold University College, Kongsberg, Norway

Lene A Hagen, Stuart J Gilson, Rigmor C Baraas

S-cone spatial acuity test may reveal S-cone dysfunction not easily detected by pseudo-isochromatic tests

Time: 09:20 - 09:35Session: Isihara symposium

SUNDAY 5 JULY

31

In his paper published in 1916, Ishihara described that his new pseudo-isochromatic test plates for color deficiency should accomplish four principles as follows: (1) both color normal and deficient people can read, (2) color normal and deficient people can read but as different characters, (3) only color normal people can read, but not color deficient people, (4) only color deficient people can read, but not color normal people. Ishihara emphasized in his paper that the principle (2) was the most important feature for improvement of pseudo-isochromatic test plates in order to distinguish color normal and deficient people. In this study we explored how these principles are realized in Ishihara test plates by analyzing colors of dots in the plates using the LMS cone space. We used Ishihara’s Test for Color Deficiency II (International version 38 plates) (2013) as test stimuli. The spectral reflectances of dots, which form figures and backgrounds in the plates, were measured by a spectroradiometer (TOPCON SR-LEDW). The L, M, S coordinates of the dots were calculated under the 6500K black body illuminant. The plate No.8, for example, is read as “74” for normal trichromat, but as “21” for dichromats. The figures of 7 and 4 are formed by dots with five greenish colors, and the background dots consist of five reddish colors. Two of five figure colors are fairly well aligned on a line with three of five background colors both in the L-S plane and the M-S plane, and these two figure colors and three background colors are separately aligned in the L-M plane. This means that these two figure colors are seen as parts of the background so that “7” and “4” appear as “2” and “1”, respectively, for dichromats. We confirmed in this example that the principle (2) was beautifully realized in Ishihara test plates. We further tested robustness of Ishihara test plates under different illuminants, and confirmed that these features held in a wide rage of illuminant color temperatures from 3000K to 20000K.


1Department of Information Processing, Tokyo Institute of Technology, Japan2Department of Information Design, Kogakuin University, Japan

Keiji Uchikawa1, Yumiko Muto1, Kazuho Fukuda2

Characteristics of Ishihara pseudo-isochromatic test plates in LMS cone space


SUNDAY 5 JULY

32

It has been known that dichromatic old-world primates show better performance in breaking color camouflage sightings. Instead of having wild type loci, they carry S gene (in 7th chromosome) and only one hybrid L/M locus in X-chromosome, so due to limited color perception, dichromats would not be distracted by colors of back- and foreground objects and could see the texture difference easier than trichromats. On the other hand, trichromats discriminate certain red-green hues better than dichromats. In female, there are processes by which one of the two copies of the X-chromosomes is randomly inactivated in any given cell and it will remain inactive throughout the lifetime of the cell (Lyonization). So a female carrier may possesses wild type and the hybrid opsins (S, M, L and L4M5). If a female possesses L4M5 opsin, irrespective of the other three wild type ones we may intuitively expect that the female would also have the advantage of breaking color camouflage. In this study, we tested color perception of female carrier monkeys bearing the L4M5 hybrid gene in one of her X-chromosomes. First, we tested if they could discriminate the target determined by certain red-green hues which dichromats hard to discriminate. This is a trichromatic advantageous paradigm. Second, we assessed if they have the same advantage in breaking color camouflage as shown by dichromatic macaques. Target was determined by luminance contrast and red-green noise was added. This is a dichromatic advantageous paradigm. We compared the performance of female carriers, normal trichromats and protanopic dichromats, and found that the carriers showed comparable performance as dichromats in breaking color camouflage and as trichromats in red-green color discrimination. We assume that the existence of L4M5 opsin reduced the number of L opsin in the retina. It made the Red/Green channel less effective but sufficient to pass the colorblind test. This also made the color camouflage ineffective.


1Department of Biology, Bogor Agricultural University, Bogor, Indonesia2Department of Cognitive and Behavioral Science, Graduate School of Arts and Sciences, The University of Tokyo, Japan 3Faculty of Human Wellbeing, Chubu Gakuin University, Seki, Japan

Kanthi A Widayati1, Bambang Suryobroto1, Atsuko Saito2, Akichika Mikami3

Ability of female color blind gene carrier monkeys in breaking color camouflage and discriminating colors


SUNDAY 5 JULY

33

Philippe Lanthony loved the colors in the broadest meaning, as he used to say by himself. As an ophthalmologist he devoted oneself to color vision, in particular to color vision testing by means of pigmentary color tests. He developed new arrangement tests, above all the Lanthony’s Desatured Panel D-15 and later the New Color Test. The former, universally adopted by the practitioners, stressed the first clinical sign of acquired the color vision deficits, i.e. the apparent desaturation of colors. Philippe Lanthony was the coauthors of several reports on color vision. He was member of the IRGCVD right from the beginning, later of the ICVS.Philippe Lanthony was fascinate by the arts of paintings. He published three major books on paintings, “Des yeux pour peindre” (2006) (translated in several languages), “Lumière, vision et peinture” (2009), “Histoire naturelle de la vision colorée” (2012) and many other monographs and papers. He initiated an exhibition of Claude Monet in Paris in 2008.With these contributions he hands us an exceptional treasure down.It is not necessary to outline that Philippe Lanthony was a warm friend for all of us.

Corresponding author: [email protected] School of Geneva, Switzerland

André Roth

Remark: Philippe Lanthony, our friend (1929-2014)

Time: 10:45 - 11:00Session: Special session in the memory of Dr. Lanthony

SUNDAY 5 JULY

SPECIAL SESSION IN THE MEMORY OF DR. LANTHONY

34

Visual performance can be greatly enhanced by the use of colour signals, particularly when the work environment consists of large visual fields and cluttered scenes. Colour has long been established as an important object feature that improves visual performance in visual search (VS) tasks by enhancing conspicuity and hence by shortening VS paths. In addition colour can be used to declutter the scene by grouping together objects of interest and by signaling specific information through colour coding. The effect congenital colour deficiencies (CCD) can have on VS for redundantly coloured targets has been investigated previously. It was concluded that reduced chromatic sensitivity results in longer search times. The extent to which chromaticity changes alter directly target luminance contrast (LC) as seen by subjects with congenital deficiency and in turn, the extent to which such changes affect VS times remain uninvestigated. The aim of this study was to extend these findings by examining how reduced chromatic sensitivity affects the different uses of colour in VS and to compare the relative importance of red/green (RG) and yellow/blue (YB) colour signals when the task involves large visual fields. In addition we also wanted to establish whether the longer VS times measured in CCD subjects can be attributed entirely to the reduced RG sensitivity or whether other factors are also involved. All subjects (n = 50) had their RG and YB colour vision assessed using the CAD test. We generated VS tasks consisting of various combinations of distractors and targets. The subjects made two responses following each presentation. The first response measured the subject’s VS time whilst the second provided a measure of false positive responses. The initial experiments explored how LC affects VS in normal trichromats and in CCDs in the absence of colour signals. The remaining experiments explored how the addition of colour signals on increasing strength affected VS times.The results show that normal trichromats benefit significantly from the addition of colour signals. In general, subjects with CCD produce VS times which are equivalent to those measured in normal trichromats, but only when the results are expressed in their own RG threshold units. This was not however the case for all combinations of colour and LC polarity. Some CCDs can perform worse with increasing chromatic saturation, largely because the increased colour signal reduces the effective LC of the target and this has a direct effect on the measured VS times. The results also show that the use YB signals have greater benefit on VS, particularly when larger visual fields are involved. This observation was investigated further by measuring RG and YB thresholds as a function of eccentricity. The more rapid loss of RG sensitivity with increasing stimulus eccentricity can largely account for these findings.

Corresponding author: [email protected] Vision Research Centre, City University London, London, UK

Joseph D Hickey, Marisa Rodriguez Carmona, John L Barbur

New insights into congenital colour deficiency and visual search


SUNDAY 5 JULY

35

The aim of this work was to test how perceptual models of color deficiencies predict the performance of dichromats and anomalous trichromats on a hue scaling paradigm. Brettel’s transformation and a transformation of the stimuli based on the anomalous photopigments proposed by DeMarco et al. (1992 J. Opt. Soc. Am. A, 1465) were the models used. Stimuli presented on a calibrated Display++ monitor consisted of a square target of variable color displayed at the center of a uniform D65 background. Both target and background had the same luminance of 12 cd/m2 and subtended 2-deg and 20-deg, respectively. In order to scale the component sensations of red, green, yellow and blue observers were instructed to assign to each target one or two unique-hue names from a list of 13 unique and binary-hue names displayed on the left-side of the monitor. Namely, five Hering primaries (red, green, yellow, blue and grey) and eight binary-hue names (red-yellow, yellow-red, yellow-green, green-yellow, green-blue, blue-green, blue-red and red-blue) were used. An arbitrary scoring rule assign a value of 3 when the stimulus is described with a single hue name and if two names were used a value of 2 to the predominant hue and 1 to the other hue. In the normal condition, the colors of the target were selected in 24 directions around standard D65 illuminant in L*c*h* color space and the hue-angle step was always 15-deg. The experiment was carried out by two deuteranopes, two protanopes, two deuteranomalous and one protanomalous. In the simulation condition, corresponding to Brettel’s and DeMarco’s transformation of the stimuli of the normal condition, three normal color observers participated in the experiment. For dichromacy, the hue scaling functions for the two conditions showed to be different. For anomalous trichromacy they were similar. These results suggest that DeMarco transformation predicts anomalous trichromats perception better than Brettel’s model predicts dichromats perception.


1Department of Physics, University of Beira Interior, 6201-001 Covilhã, Portugal2Centre of Physics, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal

Vasco MN de Almeida1, Jorge LA Santos1, João MM Linhares2, Catarina AR João2, Sérgio MC Nascimento2

Predicting hue scaling for abnormal color vision with perceptual models of color deficient vision


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Congenital achromatopsia (ACHM) is an autosomal recessive disorder characterized by impaired visual acuity, absent colour vision, nystagmus and photophobia. Crucial to the success of emerging gene therapy trials for ACHM is the development of accurate outcome measures to monitor treatment efficacy. Although colour vision loss may be one of the least troublesome manifestations of ACHM, its measurement has the potential to be a valuable assessment tool in ACHM clinical trials.

We recruited 11 patients with confirmed mutations in the CNGB3 gene, 2 patients with unconfirmed mutations (aged 14-56), and 13 normal subjects (aged 23-49). ACHM patients completed 2 trials of the Colour Assessment and Diagnosis (CAD) test, modified to display fewer hues to reduce test duration, and larger stimuli to compensate for reduced visual acuity. Additionally, temporal frequency was lowered by 50% and random luminance modulation was increased by 100% to mask the detection of rod-mediated signals. Normal subjects completed the test using both the standard and modified parameters.

ACHM patients had higher thresholds (29.2 to 38.3 CAD units for red-green and 12.1 to 15.2 for yellow-blue) than normal subjects (1.16 to 2.04 and 0.91 to 1.73), using the modified protocol. Whether the lower thresholds observed in some ACHM subjects were due to ineffective luminance masking or in fact represented genuine residual colour vision is yet to be determined. There was a small learning effect between trials for red-green thresholds (p <.05), however the ACHM patients with the lowest thresholds showed excellent repeatability.

Despite the challenges that ACHM poses for measurement of colour vision, the current findings support the continued exploration of the CAD test in this patient group. Further research to determine the effects of temporal frequency and random luminance modulation on performance will enable identification of optimum CAD parameters for use in ACHM.

Corresponding author: [email protected] College of Wisconsin, USA

Emily J Patterson, Christopher S Langlo, Joseph Carroll

The use of the Colour Assessment and Diagnosis (CAD) test in congenital achromatopsia


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MONDAY

38

Are objects remembered with a more saturated colour? Some of the evidence supporting this statement comes from research using ‘memory colours’ – the typical colours of particular objects, for example the red of roses. The problematic aspect of these findings is that many different exemplars exist, some of which might exhibit a higher saturation than the one measured by the experimenter. Here we avoid this problem by using unique personal items and comparing long- and short-term colour memory matches with those obtained with the object present. Participants (N=12) brought personal coloured objects (clothes, etc.). In absence of the object, we secured from the owner a long-term memory match (O-LTM) to it. The match was performed in a room under neutral daylight illumination by selecting the chip that best resembled their memory colour of the object from the Munsell Book of Color (Glossy Edition). Participants that were naïve to the objects (N=11 or 12 depending on object) performed the same selection task immediately after looking at each object for 30 seconds (short-term memory match, P-STM). Subsequently, the same participants (P-OM) and owners (O-OM) of the object provided an object-match under daylight with chips and objects present. Direct comparison of O-OM and O-LTM allows us to establish that not all owners remember the object as more saturated (6/12 selected a chip with higher Munsell Chroma in the memory match but 3 selected one with the same and remaining 3 chose chips with lower Chroma). In the case of participants newly introduced to the object the comparisons between their short-term memory matches and their chosen chip when the object is present also present a varied picture dependent on participant and object. Our results show that the shifts to higher levels of saturation previously reported are not a consistent finding that extends to all objects or participants.


1Bradford School of Optometry and Vision Science, University of Bradford, UK2Giessen University, Germany

Marina Bloj1, David Weiss2, Karl R Gegenfurtner2

Remembering object colours

Time: 09:00 - 09:15Session: Colour cognition 1

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COLOUR COGNITION 1

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It has been argued that infants’ colour memory is categorical (e.g., Franklin & Davies, 2004, BJDP, 22, 349-377). It has also been shown using data from the World Colour Survey that there are common categorical clusters and distinctions across colour lexicons (e.g., Kay & Regier, 2003, PNAS, 100, 9085-9089). Here, we investigate the similarity between the distinctions that infants make in their colour memory and common clusters and ‘fault lines’ in the world’s colour lexicons. Colour memory in 4-6 month old infants (N=356) was assessed using colours systematically sampled from the World Colour Survey stimulus array and a novelty preference method. During familiarisation, one colour was shown repeatedly to the left and right of central fixation for eight 8 second trials, then during a test phase a novel colour was shown alongside the familiar colour with its left/right location changed randomly across 4 trials. A significant preference for the novel colour over the familiar colour indicates that infants’ distinguish the two colours in their colour memory. Hues were sampled at regular intervals around the hue circle and every hue was paired with its adjacent hue (with hue differences being greater than chromatic discrimination thresholds at 4-6 months). There was significant novelty preference for four colour pairs in blue-green, green-yellow, blue-purple and purple-red regions, but no novelty preference within green, blue, purple and red-yellow regions even when hue differences were maximised. The colour pairs for which infants had novelty preferences were found to straddle common ‘fault lines’ in the world’s colour lexicons, and could be explained by cone-contrast mechanisms. Overall, the findings suggest a biological basis for certain colour distinctions which could provide constraints on how colour lexicons form. Supported by a European Research Council funded project (‘CATEGORIES’, 283605) to AF.

Corresponding author: [email protected] Sussex Colour Group, School of Psychology, University of Sussex, UK

Anna Franklin, Alice E Skelton, Gemma Catchpole

The biological basis of categorical distinctions in infant hue memory and a similarity to commonalities in the world’s colour lexicons.


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A series of recent studies on categorical color regions (Lindsey and Brown, 2006, 2009, and 2014) have demonstrated that the optimal number of color categories and “motifs” for categorical color clusters can be derived by applying the k-means cluster analysis of free-naming results. The most prominent feature of the motif differences was the type of naming on blue and green color chips; some motifs treat blue and green as a unified category. In Japanese a color term “ao (literally means blue in English)” is sometimes used to represent the appearance of green foliage covering a mountain and a green traffic signal. Therefore, it is possible that the unified category in the blue and green color chips could be found as one of the motifs by analyzing free-color naming results. We made k-means cluster analysis on the result of free-color naming by 52 native Japanese-speaking participants. The participants were instructed to name 330 Munsell color chips, from the WCS (World Color Survey) color samples, including 10 achromatic chips, with monolexemic color terms in a free-naming session. The results of k-means analysis with a gap statistic have shown that the optimal number defined by the statistics was 13 for chromatic categories, in addition to three achromatic categories. The chromatic categories included eight basic color terms: red, blue, green, yellow, orange, purple, pink, and brown. The non-basic color terms were two from “kon (literally, indigo)”, “matcha (green tea)”, “cream”, “enji (reddish brown or dark red)”, and “yamabuki (kerria)” which varied across iterations, in addition to “mizu (water or cyan)”, “hada (skin)”, “oudo (sand or mud)”. The green and blue categories were clearly separated in all subjects. Also, all subjects consistently used cyan or a similar term, which resided in the blue-green border. Therefore, the color categories of the blue-green region is estimated to be separated with two or more categories in the motif analysis.


1Tohoku University, Japan2Tokyo Institute of Technology, Japan3Kogakuin University, Japan4Ritsumeikan University, Japan5Ohio State University, USA

Ichiro Kuriki1, Yumiko Muto2, Kazuho Fukuda3, Rumi Tokunaga4, Delwin T Lindsey5, Angela M Brown5, Keiji Uchikawa2, Satoshi Shioiri1

Categorical color clusters of Japanese color lexicon


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41

The role of colour in verbal communication extends far beyond its denotative function, with specific colours inspiring their own cultural associations and symbolic uses. Here, two samples of 23 and 26 British respondents (23 F; 18 F, 8 M) provided free associations to eight colour stimuli: four cardinal hues and four “binary” hues. Both samples gave totals of 1214 associations from the samples, including 542 and 645 unique tokens. Breaking associations into conceptual, natural-object and made-object word classes, these respectively contained 215 and 351; 200 and 178; 127 and 116 tokens. Correspondence Analysis was applied to each class separately to represent its constituent associations, and the hues, as points within a geometrical space. Results were compared to earlier spatial models obtained for data from 37 Indian respondents (Bonnardel et al., 2013). For both cultures, natural-object associations were largely iconic with cross-cultural or archetypal features (e.g. red and orange: fire), and formed an opponent-hue pattern. Conceptual associations were symbolic, often conventional, often idiosyncratic to single respondents, and more culture-specific (e.g. red: Stop, purple: Catholic). They required a three-dimensional model, with Warm-Cool as one dimension. In the realm of made objects, colour acts as an index, but no clear structure emerged from the CA solution.

Bonnardel, V. Dubey, N., Beniwal, S. and Pande, M. (2013). Colour association in a young adult Indian population. ICVS2013, 22nd Symposium of the International Colour Vision Society, Winchester, UK, 14-18 July 2013: Abstract book, edited by Valerie Bonnardel, John Barbur & Marisa Rodriguez-Carmona, Colour Group (Great Britain), 154


1School of Psychology, Massey University, New Zealand2School of Psychology, University of Winchester, UK

David L Bimler1, Christina Levanzin2, Louise Heath2, Nikki Amos2, Valérie Bonnardel2

Colour symbolism and associations in a UK population


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A comparison of British (N=80) and Indian (N=57) young adults' color preferences revealed a robust gender difference and a more subtle cultural difference, mainly expressed by females. Males and females prefere cool over warm colors, in addition, females express a preference for pink-purple colors whose exact shade is culture-specific (Bonnardel et al., 2012). Here the study is extended to French young adults, tested in the same experimental conditions using a triadic task and sixteen colors (Bimler & Kirkland, 2009) . A MANOVA limited to French participants (21F and 12 M), with the 16 color ratings as dependent variables, indicated a significant gender effect in pairwise comparisons for four colors (light pink, pink, dull green and beige). A second MANOVA, including the three nationalities, showed medium effect sizes from gender and nationality (PartialEtaSquared = 0.24 and 0.35 respectively). Females ranked pink and light pink higher while males ranked light blue, olive green, brown and beige higher. Indians' rankings were higher for olive green (compared to British) and pink (compared to British and French); British ranking was higher for lavender (compared to Indian) and French ranking was higher for beige (compared to British). These additional results if confirmed with the full set of participants provide support to early observations of a cross-culture gender difference involving the pink-purple color interval and a culture-specific difference that might be mainly expressed by females.

Bonnardel, V. Beniwal, S., Dubey, N. Pande, M & Bimler, D. Colour preferences: A British/Indian comparative study. AIC2012, In Color we live- Color and Environment, Interim Meeting of the International Colour Association, Taipei, Taiwan, 22-25 September 2012: Conference Proceedings, edited by Tien-Rein Lee and M. James Shyu, Taipei, Color Association of Taiwan (CAT), 306-309.Bimler D, Kirkland J. Colour-space distortion in women who are heterozygous for colour deficiency. Vision Res 2009;49:536-543

AcknowledgementsWe thank F. Viénot for her generous contribution at the early stage of this work.


1Department of Psychology, University of Winchester, UK2EnsadLab, Ensad, Paris, France3School of Psychology, Massey University, New Zealand

Valérie Bonnardel1, Christian Stenz2, Vonnik Hertig2, Nathalie Junod-Ponsard2, David L Bimler3

Gender difference in colour preference: A cross-cultural study


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43

INTRODUCTION: Mid-level vision is a neural representation of surfaces and objects, later than the representation of the physical retinal image but before object recognition. Though critical for perception, mid-level vision can be difficult to isolate from lower-level neural processes. Here, mid-level neural representations that are ambiguous for color provide an approach to determine how resolution of ambiguity depends on object grouping. METHOD: Ambiguous mid-level neural representations were created with chromatic interocular-switch rivalry (CISR), in which two equiluminant but chromatically rivalrous circles (say, one “purple” and one “green”) were presented separately to each eye in a corresponding retinal location. When the chromaticities were swapped between the two eyes several times a second (e.g., 3.75Hz), the observer saw a fused circle but not one that rapidly switched in hue; instead, the color percept was a longer-lasting hue that alternated slowly between the two rivalrous colors (Christiansen, D’Antona & Shevell, 2014). Two such CISR circles, one above fixation and one below, were presented either singly or, in separate runs, simultaneously. During each 60-sec run, the observer reported (via button presses) the perceived hue(s) of the circle(s) in the fused binocular percept. The chromaticities swapped in CISR differed in only L and M excitation or, in separate sessions, only S excitation (time-average chromaticity always EES ‘white’). RESULTS/CONCLUSION: If grouping of two separated circles influences the resolution of their color percepts, then the probability of simultaneously perceiving both circles as identical in color would be greater than predicted from the independent probabilities of perceiving that color in each circle seen alone. Results confirmed the influence of grouping (p<0.01 for each of 3 observers). Object grouping, therefore, alters the perceptual resolution of ambiguous chromatic neural representations in mid-level vision.


1Department of Psychology, University of Chicago, USA2Department of Ophthalmology & Visual Science, University of Chicago, USA3Institute for Mind & Biology, University of Chicago, USA4Department of Psychology, University of Copenhagen, Denmark

Steven K Shevell1,2,3, Wei Wang1,3, Jens Christiansen4

Resolution of ambiguous neural representations of color in mid-level vision


MONDAY 6 JULY

COLOUR COGNITION 2

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We have previously shown that observers can select, when given a two-alternative-forced-choice, the mean hue of a multi-hue ensemble presented for 500ms (Maule & Franklin, under review). This indicated the conditions under which observers were better-than-chance at selecting means, but did not provide a measure of the accuracy of mean encoding. Here, we investigate the accuracy of mean encoding, the influence of categories and the underlying mechanisms of rapid averaging. Following brief (500ms) presentation of heterogenous (multi-hue) and homogenous (single-hue) ensembles, observers (N = 15) were allowed to freely adjust the hue of an array until they felt it represented the mean hue of the ensemble just seen. Settings were compared to the expected mean hue, based on a JND-scaled hue circle, to identify the accuracy of mean representation. Results indicated that the observers converged extremely closely on the expected mean hue for both heterogenous and homogenous ensembles. However, absolute error from the expected mean was greater for heterogenous than homogenous ensembles, by approximately half a JND. Based on individual observer colour naming we also found that the number of different colour categories present in a multi-hue ensemble had no effect on the accuracy of adjustment to the mean. The lack of a category effect strengthens arguments for early and automatic perceptual averaging. Statistical modelling of the data identified the likely number of elements which participants include in their estimates of mean hue. This contributes to the debate about whether the full ensemble is included in the average estimate or whether perceptual averaging is due to sub-sampling of relatively few items. The findings have implications for the perception of variegated scenes, colour memory and encoding of object surface colours.

Supported by an ESRC studentship to JM (ES/J500173/1), and a European Research Council funded project ‘CATEGORIES’ (283605) to AF.

Corresponding author: [email protected] Sussex Colour Group, School of Psychology, University of Sussex, Brighton, UK

John J Maule, Anna Franklin

Accurate estimation of the mean hue of rapidly presented multi-hue ensembles


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45

Studies of “ensemble coding” have demonstrated that observers can readily extract the summary statistics of images including the average value of a stimulus set, for dimensions ranging from orientation to facial expressions. In previous work we examined the ability to judge the average value of pairs of colors by using a method of adjustment to set the pair to a specified average. Performance on these tasks suggest that observers are good at judging the relative strength of different hues; while surprisingly poor at inferring the actual average value of different hue combinations, especially for pairs that include distant color categories. This pattern suggests that observers may not form or have access to an explicit representation of the average of different hues. To test this, in further work we are extending these studies to explore ensemble color perception using brief presentations and judgments more characteristic of the paradigms that have revealed averaging percepts in other stimulus domains. Observers view collections of spots that vary in hue angle or saturation or both, and are then probed with a range of test stimuli to report whether they were present or absent in the set. Our aim is to determine whether ensemble coding of color involves an implicit or explicit representation of the mean of a color array and whether this representation differs for and reflects independence for the dimensions of hue and saturation.

Supported by EY-10834

Corresponding author: [email protected] of Nevada, Reno, USA

Jacquelyn Webster, Michael A Webster

Averaging across qualitatively different categories


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46

The aim of this work was to compare the preferred chromatic composition for unfamiliar paintings with the original. Ten paintings were digitalized with a hyperspectral imaging system. Stimuli were images of the paintings generated by rotating the color volume obtained with D65 illumination around the L* axis in the in CIELAB color space. The images were presented on a calibrated CRT computer screen driven by a ViSaGe MKII. Four paintings were abstract from Amadeo de Souza-Cardoso (1887-1918), two had figurative elements from the same painter, two were abstract and two were figurative from other painters. In the first experiment the observer adjust the angle of rotation by actuating on a joy-pad. In the beginning of each trial a painting selected at random from the set was presented with its color volume rotated by angle selected at random in the range +180 deg – -180 deg. The task of the observer was to adjust the angle of the chromatic rotation such that the painting produced the best subjective impression. In a second experiment the threshold to perceive a chromatic change from the original composition was estimated. Three groups of observers carried out the experiment: 50 without previous knowledge of the paintings neither any formal artistic education, 8 experts in art but unfamiliar with the paintings tested and 6 experts in the paintings of Amadeo de Souza-Cardoso. It was found that the distribution of angles selected for data pooled across paintings for the non-specialist observers could be described by a Gaussian function centered at -2 deg, i.e. very close to the original colors of the paintings, and with a FWHM of 64 deg, just about 1.5 above the threshold to detect a chromatic change. In the first experiment experts produced similar results except that the FWHM was almost at threshold level. These result suggest that painters are able to predict well what compositions of colors observers prefer.


1Centre of Physics, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal2Departamento de Conservação e Restauro & REQUIMTE-CQFB, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal3Departamento de Conservação e Restauro & Research Unit VICARTE: Vidro e Cerâmica para as Artes, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal4Fundação Calouste Gulbenkian, Av. de Berna, 45 A, 1067 - 001 Lisboa, Portugal5Casa das Histórias Paula Rego, Av. da República, 300 2750-475 Cascais, Portugal6Escola das Artes, Universidade Católica Portuguesa (UCP), CITAR, 4169-005 Porto, Portugal7School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL, UK

Sérgio MC Nascimento1, João MM Linhares1, Catarina AR João1, Cristina Montagner2, Maria J Melo2, Márcia Vilarigues3, Maria H Freitas4, Catarina Alfaro5, Ana Bailão6, Kinjiro Amano7

Preferred chromatic composition of unfamiliar paintings is similar to original


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47

It was recently shown that object category labels (‘leaf, ‘sink’, etc.) boost otherwise unseen suppressed objects into visual awareness (Lupyan and Ward, 2013, PNAS, 110, 14196–14201). We investigate whether colour terms likewise influence the detection of suppressed colours or colour associated-objects. Targets were temporarily suppressed from visual awareness with continuous flash suppression (the target is presented to one eye and rapidly changing visual noise to the other). In Experiment 1 we replicated the general finding of Lupyan and Ward using greyscale photos of objects as targets. These were either preceded by a congruent object category label (20% of trials), an incongruent label (5% of trials) or white noise (25% of trials). On remaining trials no target was presented. Detection sensitivity (d’) and hit rates were significantly poorer for target objects preceded by an incongruent label compared to a congruent label or noise. In Experiment 2 we investigated whether the detection of colour is influenced by colour terms (‘red’, ‘yellow’, etc.). Targets were coloured circles preceded by a colour term, which matched the target on congruent trials and did not match on incongruent trials. We found detection sensitivity was significantly worse on incongruent trials. Further, reaction times were significantly faster for congruent trials. In Experiment 3 we used greyscale targets objects preceded by a colour term. On congruent trials the colour term was diagnostic of the object’s characteristic colour (e.g., ‘orange’ for basketball), whereas on incongruent trials the colour term was not. We again found that detection sensitivity was significantly poorer on incongruent trials compared to congruent or noise trials suggesting colour terms can affect our awareness of colour-associated objects as well as colours. These findings are related to theory on the role of colour terms in vision and cognition and to the phenomenon of object memory colour.

Corresponding author: [email protected] of Sussex, UK

Lewis Forder, Olivia Taylor, Helen Mankin, Ryan Scott, Anna Franklin

Colour terms affect detection of colour and colour-associated objects suppressed from visual awareness


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48

Sir Isaac Newton wrote that the rays are not coloured. Then how are the perceived colors generated from the rays in the brain? After 300 years from the days of Newton, we are now approaching to the stage where we can talk about the entire story of color signal transformation from the retina to the higher cortical areas. At the early stage in the retina and LGN, color signals are decomposed by the color opponent neurons into two axes (L-M, S-(L+M)) by computing differences among signals from different types of cones. A significant step occurs at the primary visual cortex where nonlinear transformation of color signals convert two-axes into multi-axes representation of color where neurons tuned to various directions in the color space are formed. This is as if compressed color signals are unzipped in the cortex taking advantage of the proliferation of cortical neurons and assigning different colors to different neurons. Such multi-axes representation of color is also observed at each area along the ventral visual pathway including areas V2, V4 and the inferior temporal (IT) cortex, and this seems to be the basic principle of the way color is represented in the visual cortex. In both humans and macaque monkeys, damage in the higher ventral cortex cause permanent damage in color perception, indicating that this area plays critical roles in color vision. In the IT cortex, the higher ventral cortex of the macaque monkey, neurons exhibit properties closely associated with color perception. We are now having gradually detailed picture on the functional organization of the IT cortex in relation to color where constellation of multiple subregions exist. Our recent study (Namima et al. J Neurosci 2014) have shown that there is some important difference between those subregions in a way color signal is represented. It is shown that color selectivities of the neurons in the posterior IT cortex are affected by the luminance contrast whereas those in the anterior IT cortex are not, indicating that color is represented independently of luminance contrast in the anterior IT cortex, the final stage of the cortical color processing.

Corresponding author: [email protected] Institute for Physiological Sciences, Japan

Hidehiko Komatsu

How are the rays coloured in the brain?


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INVITED TALK 3

49

A long-wavelength target that is sufficiently brighter than its surroundings can appear pure yellow. Made sufficiently dimmer, it can appear pure brown. In between, the target will appear butterscotch, a variable mixture of yellow and brown. Past work has shown that the target light level of the brown boundary between butterscotch and brown is highest when the bright surround is contiguous with the target and stimulus duration is at least 1s, but distant surround features and 30ms stimulus duration also induce brown.

Here we show that these stimulus variations have similar effects on the light level at which stimuli appear pure yellow with no trace of butterscotch, the yellow boundary. Observers marked brown and yellow boundaries by adjusting the luminance of a long-wavelength target (which they also adjusted to a red-green null) in the presence of constant-luminance surround rings of variable proximity to the target (0°, .25°, 1° target-surround gaps) and for two stimulus presentation durations (0.03s, 1s). Despite their very different light levels, the brown and yellow boundaries tend to move together, separated by a constant butterscotch range, suggesting that a common mechanism modulates both. There is considerable variation across observers in the size of proximity and duration effects and in the overall light level of brown and yellow boundaries but, within observers, both brown and yellow boundaries tend to be influenced similarly, with a constant butterscotch range for both contiguous and distant surrounds and a constant stimulus duration difference.

Separate brightness matching experiments using these same surround and duration variations show that target brightness is also modulated in a similar way. This leads to the hypothesis that the same visual processes that control brightness/darkness induction also control the light levels of both brown and yellow boundaries. We plan future studies to evaluate this hypothesis.


1Psychology, University of Washington, USA2Department of Information Processing, Tokyo Institute of Technology, Japan

Steven L Buck1, Takuma Morimoto2, Tanner DeLawyer1, Brooke Stoehr1, Andrew Shelton1

Spatial and temporal influences on brown and yellow

Time: 16:30 - 16:45Session: Colour induction & constancy

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COLOUR INDUCTION & CONSTANCY

50

Previous research from our lab has shown that sufficiently bright surrounds will change the hue of a target stimulus from yellow to brown. Additionally, surrounds that are contiguous with the target will induce the perception of brown at higher target light levels than will surrounds that are not contiguous with the target. We briefly presented (1s, .5s, and .25s) a 4°-diameter foveal target disk to either exclusively to one eye (monocular and dichoptic conditions) or simultaneously to both eyes (binocular condition) of 8 observers. A bright 2° width surround annulus was presented either in the same eye(s) (monocular and binocular conditions) or in the opposite eye (dichoptic) as the target. The target and surround were physically contiguous when presented in the same eye and were perceptually contiguous when presented in separate eyes. Observers freely adjusted the luminance of the target until it was at the highest light level where it appeared brown with no trace of yellow, the brown boundary.

For all observers, the target’s brown boundary was at significantly (p<.001) higher light levels in monocular and binocular conditions than in dichoptic conditions. Shorter stimulus presentation times (.5s and .25s) produced brown boundaries at significantly (p<.001) lower light levels than the longer presentation time (1s). These results show that although a surround that is perceptually contiguous can influence the hue of a stimulus, its effect is diminished in comparison to a surround that is presented to the same eye and that stimulus presentation time has a moderating effect on brown perception. The differences in monocular and dichoptic presentation results have implications for multiple neural mechanisms for brown induction that could involve both monocular and binocular pathways as well as retinal and cortical processes. Further research is being done to attempt to determine the locus of these effects.

Corresponding author: [email protected], University of Washington, USA

Tanner DeLawyer, Hohjin Im, Cody Smith, Steven L Buck

Dichoptic perception of brown


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51

We separated the effects of lateral interactions and adaptation on two aspects of color and brightness induction with a new measurement method. First, we tested whether dark induction is stronger than light induction, as claimed by reports based on experiments that did not separate adaptation effects from lateral interactions. Second, we tested whether blurring the edge between test and surround reduces the magnitude of induction, as predicted by almost every model. Observers fixated an annulus (0.66° to 2.0°) inside a 12° square. Annulus edges were either sharp or sinusoidal or linearly blurred. Surround color was modulated as a 0.5 or 4.0 sec half-sinusoid between Grey and one of six poles of DKL space: roughly Light, Dark, Reddish, Greenish, Yellowish, Bluish. For a steady Grey annulus, surround modulation induced a perceived color or brightness shift towards the opposite pole. Magnitude of the perceived shift was estimated by nulling it with a fraction of the surround modulation presented inside the annulus, using an adaptive double-random 2AFC staircase. Trials alternated surround modulation to opposite poles to maintain time-averaged adaptation at Grey. This method revealed strong induction effects for 6 observers. There were no consistent asymmetries in induction along any axis for fast presentations. With slow presentations, Light & Dark induction magnitudes increased to further reduce asymmetry. Consequently, induction asymmetries are not due to lateral interactions, or to adaptation to the fixated stimulus, but may result from some aspects of asymmetric matching discussed by Helmholtz. Edge blur did not reduce induction magnitude for fast presentations, but sharp edges reduced the adaptation effect in slow presentations, possibly via fixational eye-movements. The lateral interactions underlying induction are thus symmetric for color and brightness, and likely involve spatially opponent filters of modest widths, rather than edge extraction mechanisms.

Corresponding author: [email protected] Center For Vision Research, State University of New York. USA

Qasim Zaidi, Romain Bachy

Effects of lateral interactions and adaptation on color and brightness induction


MONDAY 6 JULY

52

Flank transparency refers to illusory color spreading that is induced when narrow colored flanks are added to segments of black lines located within a virtual circle (Wollschläger et al., 2001). It produces the percept of a colored transparent filter with illusory contours over the lines and background. We asked whether color spreading in flank transparency is tightly associated with perceptual transparency as in neon color spreading (Ekroll & Faul, 2002), and investigated whether luminance and color conditions inducing flank transparency are consistent with the predictions by the episcotister model for perceptual transparency (Metelli, 1970). We used green or achromatic flanks and systematically varied luminances of the flanks, lines, and background. Then we asked observers to rate subjective certainty of color spreading using a five point scale. Results showed that convincing color spreading depended on color as well as luminance conditions. Our analysis revealed that convincing spreading was found when cone excitations produced by the flanks were intermediate between those of the lines and the background. These findings are consistent with the prediction by an episcotister model generalized to a cone excitation metric. Moreover, another type of convincing color spreading was also found when the flank luminance was lower than either the line or the background luminances, i.e., when the luminance condition for perceptual transparency was not met. Observers’ verbal report indicated that phenomenal transparency was not evident in this color spreading. These findings suggest contributions of different visual processes to color spreading in flank transparency displays. In one process color and luminance information in a flank region are decomposed into a transparent layer and a background, whereas in another process color spreading is not associated with perceptual scission and it is governed by other factors such as contrast between the flank and the background.

Corresponding author: [email protected] of Psychology, Faculty of Letters, Chiba University, Japan

Eiji Kimura

Two distinct types of color spreading in flank transparency displays


MONDAY 6 JULY

53

For a single matte surface, changes in surface reflectance and illumination are indistinguishable. Introducing a specular component to the reflectance properties of the surface might allow separation of surface and illuminant colours. In a series of experiments, we tested the discriminability of reflectance and illuminant changes as a function of specularity. The chromaticities in our images were constrained to be linear mixtures of the illuminant chromaticity (specular component) and the wavelength-by-wavelength multiplication of illuminant and reflectance (diffuse component). In Experiment 1 we tested observers’ reliance on the spatial distribution of chromatic information, comparing smooth spheres and phase-scrambled versions. In Experiment 2 we compared performance with bumpy and marbled spheres. The specular and diffuse components of the bumpy spheres were distributed according to the local curvature of the surface. The bumps also introduced local variations in intensity. The random patterns applied to the surface of the marbled spheres introduced intensity variation, but preserved the chromatic gradients available in the smooth spheres. In Experiment 3 we tested the role of surface motion in separating surface and illuminant colours. Reliably, across all conditions, even low levels of specularity were sufficient to support discrimination of surface and illuminant colour changes. Spatial arrangements that were interpreted as illuminated objects produced the best performance. Image motion affected performance: Rigid motion of the image impaired performance, whereas surface motions that generated parallax between the specular and diffuse components maintained performance. Subtle chromatic variation can support perceptual discrimination of surface and illuminant changes. Performance is maintained even in the presence of spatiotemporal intensity variations, especially when those variations are consistent with the geometry of illuminated, glossy surfaces.

Corresponding author: [email protected] of Experimental Psychology, University of Oxford, UK.

Hannah E Smithson, Rob J Lee

A hint of gloss is sufficient for perceptual discrimination of changes in reflectance or illumination


MONDAY 6 JULY

TUESDAY

55

It is well known that the physiological properties of vision differ among individuals. These individual differences may mediate individual difference in color perception. In order to quantitatively assess the relationship of those individual differences, we need to measure not only the color vision but also the physiological properties of the identical subjects. We focused on the optical density of macular pigments. Moreover, in our preliminary experiments we found that Asian subjects tended o have smaller L/M cone ratios compared to Caucasian subjects, which led us to predict that there will be significant difference in L/M cone ratio between races. In this research, we measured these characteristics of Japanese subjects.We estimated the L/M cone ratio in Japanese subjects using a newly developed electroretinogram (ERG) flicker photometry method. The optical density of macular pigment measurement was measured with psychophysical technique, asking a subject to set their flicker-minimum point for the flickering stimulus which were observed in their foveal and peripheral vision. The difference between the intensity of the blue light required to minimize the flicker in both conditions indicate the amount of the light absorbed in the macular pigment of that subject.We found that there is wide variety of L/M cone ratio among Japanese subjects. Compared with that of Caucasian subjects, however, the distribution of the L/M ratio of Japanese is significantly lower than that of Caucasian subjects. The distribution of the macular pigment optical density (MPOD) indicates that there are also individual differences in MPOD among Japanese, but these distributions are almost the same as those of the other races. We are currently measuring color perception of those subjects whose physiological properties were identified so that we can directly find the relationship between these characteristics and color perception.

Corresponding author: [email protected] of Informartics, Graduate School of Science and Engineering, Yamagata University, Japan

Yasuki Yamauchi, Yuki Kawashima, Keisuke Yatsu, Takehiro Nagai

Individual differences of macular pigment density and L/M cone ratio of Japanese

Time: 09:00 - 09:15Session: Variability in colour vision

TUESDAY 7 JULY

VARIABILITY IN COLOUR VISION

56

It has been argued that asymmetry between increment and decrement S-cone sensitivity provides psychophysical evidence for two separate neuronal pathways. To investigate this we examined isolated L- and M-cone increment, S-cone increment and decrement spatial acuity at 5 deg eccentricity.

Twenty-four healthy colour normal observers (16–49 yrs) were included in this study. All had normal foveal logMAR letter acuity and no known ocular abnormalities. Normal colour vision was verified with the Ishihara and HRR pseudo isochromatic plates. Spatial acuity was measured in the dominant eye with a Sloan E letter at 23% L-, M-, S-increment and S-decrement cone contrast. Achromatic spatial acuity was measured at 90% decrement contrast. Detection thresholds were measured employing a 4 AFC staircase. Background luminance was always 10 cd/m2. The Sloan E was presented at 5 deg eccentricity and stable fixation was verified by an eye-tracker. Observers were corrected to best logMAR letter acuity and viewed the stimuli monocularly from a distance of 2.3 m.

Asymmetry was calculated as the difference between S-cone increment and decrement minimum angular resolution (MAR, arcmin), with MAR differences <1.2 considered symmetric. The seven observers with symmetric thresholds had significantly better S-cone increment and decrement MAR [mean (SE); 16.9 (0.5) and 16.4 (0.6)] than the 17 whom had asymmetric thresholds [21.7 (0.6) and 18.7 (0.5)]. They also had significantly better M-cone MAR and significantly lower M:L MAR ratio [4.8 (0.3) and 1.3 (0.1)] versus [7.2 (0.6) and 2.0 (0.2)]. There was no difference between groups for achromatic or L-cone MAR. Neither age nor gender had an effect on any of the measures.

The results imply that M-cone signals are associated with the perception of both blue and yellow as well as the degree of asymmetry between S-cone increment and decrement MAR. It questions the idea that two separate neuronal pathways signal increment and decrement S-cone signals.


Department of Optometry and Visual Science, Faculty of Health Sciences, Buskerud and Vestfold University College, Kongsberg, Norway

Rigmor C Baraas, Lene A Hagen, Stuart J Gilson

Symmetry between S-cone increment and decrement spatial acuity is associated with better M-, but not L-cone increment acuity


TUESDAY 7 JULY

57

Visual sensitivity and suprathreshold color appearance are weaker along bluish-yellowish axes, possibly reflecting an adaptation to the blue-yellow bias in natural illuminants and visual scenes. We have found a strong asymmetry within the blue-yellow axis, such that stimuli on the blue side of the axis are more likely to be judged as achromatic than yellow chromaticities of the same chromatic contrast. These differences have a surprisingly large effect on how blue versus yellow colors are experienced. For example, we show that equivalent yellow contrasts appear much more colorful, and that this affects not only complex images and materials (e.g. silver vs. gold, or skin tones in a photo vs. its negative), but also highly impoverished stimuli such as uniform fields, for which there are few cues to the surface or lighting. The asymmetry also appears to play a critical role in the perception of “the dress” that recently overtook the internet. Observers differ in whether the lighter stripes appear white or blue, yet we show that these stripes become unambiguously yellow/gold when the color contrast is inverted. The blue-yellow asymmetry is not present in discrimination thresholds or in suprathreshold scaling (e.g. in the chroma values of the Munsell system), and thus may reflect a higher-level perceptual inference, and possibly a bias to attribute bluer tints to shading and the illuminant but yellower tints to the object.

Supported by EY-10834 (MW) and AG-04058 (JW).


1Department of Psychology, University of Nevada, Reno, USA2University Hospital, Neurozentrum, Freiburg, Germany3Department of Psychology, University of Regensburg & University of California, Davis, USA

Alissa D Winkler1, Lothar Spillmann2, John S Werner3, Michael A Webster1

A “high-level” asymmetry in the perception of blue and yellow


TUESDAY 7 JULY

58

Using Maximum Likelihood Difference Scaling (Knoblauch & Maloney, 2012), we measured the dependence of the filling-in strength of the Watercolor Effect (WCE) on the luminance of the interior contour for 16 observers, under conditions similar to those reported by Devinck & Knoblauch (2012, J. Vision). In the current data set, a greater than twofold variation in the estimated strength of the WCE was observed across observers as well as differences in the dependence of the strength on luminance. We used the OpenSource software JAGS (Plummer, 2003) to implement and fit a Bayesian Difference Scaling model of the data and to characterize individual differences. Bayesian methods permit greater flexibility in constructing models of the data and in analyzing sources of variation than do traditional methods. To fit the data accurately, it was necessary to include explicitly both inter- and intra-observer sources of variability in the model. Good fits were obtained by using informative prior estimates of both observer sources of variability, based on the previous results of Devinck & Knoblauch for 4 independent observers. To test further the sensitivity of the model to the prior assumptions, we also tried to fit the data using non-informative priors on the inter- and intra-individual variability. Non-informative priors were found to perform less well in characterizing individual differences in the luminance dependence of the WCE. The sensitivity to priors suggests that the data contain insufficient information to estimate within observer variability accurately, thus, justifying the reliance on the results from the previous study for variability estimates. Bayesian modeling offers a sound and elegant statistical approach for characterizing the sources of variability in psychophysical data.


1INSERM U846, Stem Cell and Brain Research Institute, Bron, France2Université Lyon 1, Lyon, France3Grenoble Institut des Neurosciences, Université Joseph Fourier, Grenoble France4Laboratoire CRPCC, Université Rennes 2, Rennes, France

Kenneth Knoblauch1,2, Peggy Gerardin1,2, Michel Dojat3, Frédéric Devinck4

A Bayesian analysis of individual differences in the perceived strength of the Watercolor Effect


TUESDAY 7 JULY

59

Parvocellular (P) and magnocellular (M) cells in the dorsal lateral geniculate nucleus (LGN) of primates receive excitatory input from one eye (monocular cells). The organization of binocular inputs to koniocellular (K) pathway cells however, remains largely unexplored. This issue is relevant for colour science because receptive fields with functional input from short-wave sensitive receptors (K-s cells, "blue-on" and "blue-off") are mostly encountered in K layers.

Here, we recorded from the LGN of sufentanil anaesthetized marmoset monkeys (Callithrix jacchus, n=3). A NeuroNexus 32-channel silicon probe was used to record extracellular single cell activity in response to pulsed achromatic and cone-isolating visual stimuli. Large-field (12 deg. diameter) stimuli were presented monocularly to each eye, or binocularly. Cells were identified by analysis of response properties and anatomical reconstruction of recording sites. Strength of functional input from the non- dominant eye (0 = no input; 0.5 = equal strength of input from each eye) and sign (+ = excitation; - = suppression) was measured at time of peak excitatory response to the dominant eye stimulation.

We found as expected only weak non-dominant eye inputs to P cells (n=16, mean -0.02, SD 0.12) and M cells (n=13, mean 0.05, SD 0.07). Strength of non-dominant inputs to K cells (n=51) was greater (mean 0.14) and more variable (SD 0.20). Weight of inputs to K-s cells ranged from -0.15 to +0.33 (mean 0.05, SD 0.16). The functional weight of non-dominant inputs to "non-blue" K cells was greater than weight of input to K-s cells (p < 0.02, Wilcoxon non-parametric rank sum test). About half (18/34, 53% of non-blue K cells get binocular inputs with weight > 0.2 whereas ~ 25% of K-s cells (4/17) do. Thus, many K cells, including K-s cells, receive excitatory input from both eyes, but the functional weight of non-dominant eye inputs to K-s cells appears to be lower than that of inputs to non-blue K cells.


1Save Sight Institute, University of Sydney, Australia2ARC Centre of Excellence for Integrative Brain Research, Australia3School of Medical Sciences, University of Sydney, Australia4Flaum Eye Institute, University of Rochester, USA5Experimental Psychology, University College London, UK

Paul R Martin1,2,3, Natalie Zeater1,2,3, Soon Keen Cheong1,4, Samuel G Solomon3,5, Alexander N Pietersen1,2,3, Bogdan Dreher3

Binocular inputs to blue-ON and blue-OFF cells in marmost lateral geniqulate nucleus

Time: 10:30 - 10:45Session: Central processing

TUESDAY 7 JULY

CENTRAL PROCESSING

60

Psychophysical sensitivity to M-L chromatic modulation decreases with visual eccentricity in comparison with sensitivity to luminance modulation, even after appropriate stimulus scaling. This difference does not seem to be of retinal origin (at least in the central 20 deg measured), so the attenuation of the M-L signal must occur at a central site. Blood-oxygenation-level dependent (BOLD) fMRI responses to equiluminant M-L cone,, equiluminant S-cone or luminance modulated circular gratings were recorded in human observers in primary visual cortex (V1) and further visual areas (V2v). In V1, the spatial frequency tuning of BOLD fMRI responses for M-L and luminance gratings was similar and for both became coarser with eccentricity. For S-cone modulation, tuning also became coarser but less rapidly so, possibly due to the different distribution with eccentricity of this receptor type. A similar pattern held in V2v. There was little evidence for a weakening with eccentricity of the M-L signal in comparison with the luminance signal. These data and those from other authors would suggest that only minor attenuation of the M-L signal occurs with eccentricity in these areas.


1MPI for Biophysical Chemistry, Göttingen, Germany2SUNY Optometry, New York, USA3University of Göttingen, Göttingen, Germany

Barry B Lee1,2, Dany D'Souza1, Tibor Auer1, Jens Frahm1, Hans Strasburger3

Dependency of chromatic responses in V1 and V2 on visual field eccentricity and spatial frequency: an fMRI study


TUESDAY 7 JULY

61

In studies of chromatic discrimination, thresholds for saturation and for hue have seldom been explicitly compared. In part, this can be explained by the difficulty of establishing a common metric for different directions in chromaticity space. In the present study, working in a rescaled version of the MacLeod-Boynton diagram, we made measurements at reference points lying on lines that pass at either 45° or -45° through the chromaticity of Illuminant D65 (which corresponded to the chromaticity of the steady background of 10 cd/m2 during the measurements). The vertical (S/(L+M)) ordinate of the space was scaled so that thresholds in the two cardinal directions were identical at D65.

At a given reference chromaticity on one of the 45° lines, we made two types of measurement: saturation (i.e. radial along the line passing through the chromaticity of D65) or hue (i.e. tangential to a circle passing through the reference point and centred on D65). The discriminanda always straddled the reference point in chromaticity. The attraction of this arrangement is that the two thresholds can be expressed in common units: all that differs between saturation and hue measurements is the phase with which the short-wave signal is combined with the L/M signal.

The stimulus field was circular, subtended 2 degrees overall, was divided into four quadrants and had a duration of 200 ms. The observer was required to identify the quadrant that differed from the other three. The stimulus luminance was on average 13 cd/m2, but each quadrant was jittered independently by ±1% to prevent luminance being used to solve the task.

At any given reference point, thresholds for saturation tend to be higher than thresholds for hue. We discuss whether this is a general law and what might be its theoretical basis.


1I.P.Pavlov Institute of Physiology, Russian Academy of Sciences, St. Petersburg, Russia2Department of Experimental Psychology, University of Cambridge, Cambridge, UK

Marina Danilova1, John Mollon2

Is it a general law that hue discrimination is better than saturation discrimination?


TUESDAY 7 JULY

62

Multiple studies have shown that subjects have difficulty with non-cardinal colors, especially in the RG/LUM and TRIT/LUM color planes (e.g., Gunther, 2014; Krauskopf, Williams & Heeley, 1982; Webster & Mollon, 1994). Solomon, Peirce & Lennie (2004) showed neurophysiologically that suppressive surrounds are particularly sensitive to luminance. We hypothesized that this might make non-cardinal mechanisms in the RG/LUM and TRIT/LUM planes more sensitive to stimulus size than are isoluminant non-cardinal mechanisms. In Expt. 1 we tested 10 color-normal subjects on visual search at four dot sizes (0.5, 1, 2, & 3°) in each of the three color planes (RG/TRIT, RG/LUM, & TRIT/LUM). A two-way ANOVA on the RG/TRIT color plane yielded a significant main effect of color axis (p=0.024, η2=0.45), a significant main effect of dot size (p<0.001, η2=0.52), but no interaction (p=0.365). The RG/LUM color plane also yielded a significant main effect of color axis (p=0.020, η2=0.47), a significant main effect of dot size (p<0.001, η2=0.65), but no interaction (p=0.282). Similarly, the TRIT/LUM color plane yielded a significant main effect of color axis (p=0.020, η2=0.47), a significant main effect of dot size (p<0.001, η2=0.48), but again no interaction (p=0.424). These results suggest that non-cardinal mechanisms in the RG/LUM color plane may be more sensitive (larger effect size) to stimulus size than the RG/TRIT plane. In Expt. 2 we tested another 10 subjects on smaller dot sizes (0.25, 0.5, 1, & 2°), to see if we could increase the effect size of dot size in the TRIT/LUM plane. Here, in the RG/LUM color plane, there was again a significant main effect of dot size (p<.001, η2=0.53). We found no main effect of dot size in either the RG/TRIT color plane (p=.751, η2=0.04) or the TRIT/LUM color plane (p=.395, η2=0.10). Thus, the RG/LUM but not the TRIT/LUM non-cardinal mechanisms do appear to be sensitive to dot size.

Corresponding author: [email protected] Department, Wabash College, USA

Karen L Gunther, Colin O Downey

Non-cardinal color mechanisms: Stimulus size matters


TUESDAY 7 JULY

63

The perceived color of an object depends not only on the spectral composition of the light reflected from its surface, but also on the visual context such as illumination and surrounding colors. Such contextual interactions are thought to underlie perceptual phenomena like color constancy. A possible neuronal basis may be modulatory lateral interactions which manifest in contextual influences on the tuning of color-selective neurons in visual cortex. Here we present a model of cortical color processing that predicts color shifts induced by chromatic surrounds. The model assumes that stimulus hue is encoded by a population of neurons with Gaussian tuning curves and color preferences distributed in color space, corresponding to the finding of distributed color preferences in primary visual cortex. Lateral inhibitory interactions between neurons sharing the same color preferences are modeled by a Difference-of-Gaussian interaction kernel. No interactions between color channels are assumed. When stimuli were presented in colored surrounds, due to the contextual modulation the readout of the model population response showed systematic shifts in the encoded stimulus hue. Hue shifts were always directed away from the hue of the surround and depended on the chromatic distance in color space between stimulus and surround hues. Strength and distance dependence of the resulting induction effects strongly depended on the configuration of the population code, like density distribution and tuning curve widths. Specifically, anisotropic distribution of tuning curves resulted in the variation of induction strength with location in color space, similar to the induction effects observed in psychophysical experiments. The results indicate that important computations in color vision that lead to perceptual hue shifts can be realized using simple neural mechanisms when color is represented by a distributed code.


1Department Biologie II, Ludwig-Maximilians-Universität Munchen, Germany2Bernstein Center for Computational Neuroscience Munich, Germany3Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität Munchen, Germany

Thomas Wachtler1,2, Christian J Kellner1,3

Lateral interactions in an anisotropic population code for color predict human color induction effects


TUESDAY 7 JULY

POSTERS

65

Giulianini and Eskew (1998) carried out chromatic detection experiments using the L and M noise masking technique. They showed that chromatic detection thresholds, elevated by the L and M noise masking, could be fitted by the simple two-mechanism model (r/g opponent and non-opponent luminance mechanisms). In their results individual differences were clearly present in detection by the luminance mechanism. It would be expected that individual differences in L/M cone number ratio in the retina might cause these individual differences in luminance detection under the L and M noise masking. In the present study we tried to find any correlation between the individual L/M cone ratio and elevation of chromatic detection threshold caused by the L and M cone masking. In experiments the detection stimulus was a 2-deg Gaussian presented at fovea by a double random staircase procedure with 2AFC response. We used a 20Hz white noise of random dots with chromaticities in the L and M cone direction. The masking noise pattern was a 6-deg square . The results showed that, in the L and M noise conditions, no individual differences were found in the r/g direction, but some individual differences appeared in the luminance direction. These results are consistent with Giulianini and Eskew (1998). Our results, obtained for two observers, showed a positive tendency between the L/M ratio and the luminance detection mechanism.Acknowledgements: we thank Dr. Eskew for his valuable comments.

Corresponding author: [email protected] of Information Processing, Tokyo Institute of Technology, Japan

Makito Sato, Keiji Uchikawa

Possible influence of L/M cone ratio on chromatic detection thresholds using L and M cone noise masking

Time: 14:15 - 16:30Session: Poster #1

SATURDAY 4 JULY

POSTER

66

The understanding of the mechanisms involved in light adaptation is a challenge not completely solved. Here, we present a model based on visual mechanisms described in the physiological and psychophysical literature able to fit psychophysical data in several stimuli conditions. We propose that the study of changes in the different mechanism and phenomena considered in our model could be a strategy to better understand light adaptation. We used a two-channel Maxwellian view optical system to measure detection luminance thresholds with the method of limits for steady (LA) and transient (SOA300) backgrounds field. With data for different retinal eccentricities (0°-15°), and adaptation luminances (0.06-110 cd/m2), preliminary results of this model were reported in a previous ICVS meeting. In this occasion we performed new measurements considering different combinations of background/test size, 10°/2°, 10°/0.45° and 1°/0.45°, and a final version of the model is presented. For steady backgrounds we describe how spatial summation changes with eccentricity and we associate this behaviour with increases in the receptive field sizes. We report changes in subtractive adaptation with both eccentricity and background field size and we connect these changes with horizontal cells and changes in their dendritic field size with eccentricity. Additionally, when we reduce the background field size, we propose that the increase in the thresholds is related with rod-cone interactions and photon noise. For transient backgrounds, we show how the gradual shift in the site of the gain control can explain the data. Finally, we believe this strategy is an interesting way to better understand the behaviour of the different visual mechanisms and phenomena involved in retinal light adaptation.


1Departamento de Óptica, Universidad de Valladolid, Valladolid, Spain.2Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, USA.3Instituto de Luz, Ambiente y Visión, Universidad Nacional de Tucumán San Miguel de Tucumán, Argentina.

Alejandro H Gloriani1, Beatriz M Matesanz1, Pablo A Barrionuevo2, Isabel Arranz1, Luis Issolio3, Santiago Mar1, Juan A Aparicio1

A model for foveal and parafoveal sensitivity that could help our understanding about light adaptation


MONDAY 6 JULY

67

Rod signals access all three primary retinogeniculate pathways under mesopic illumination. Their relative weights change with the temporal properties of the rod signal. Here we studied the effect of invisible, pathway specific noise on rod signaling to examine if rod weights are modified by noise that has no direct role for perception. Stimuli were generated using a 4-primary photostimulator to independently control rod and cone excitations (5 photopic Td). Rod Frequency of Seeing (FoS) curves (Weibull functions) were measured for a range of pulsed incremental stimuli of different durations (50 – 250 ms; method of constant stimuli) in the presence (or absence) of temporal white noise that was spectrally flat (0-255 Hz) and invisible to participants (sub-threshold). Three types of white noise were employed, each transmitted through the inferred MC- (L+M+S-cone noise), PC- (+L-M noise) or KC-pathway (S-cone noise). We show that pathway specific invisible noise has different effects on the rod FoS curve when compared to the control (no noise) condition. With MC pathway noise, rod thresholds increase at short durations and the Weibull slope steepens. With PC pathway noise, rod thresholds increase at all durations with small changes in the Weibull slope. With KC pathway noise, there are small increases in rod thresholds at all durations and shallower Weibull slopes. We infer that the change in Weibull slope in the presence of invisible noise reflects a change in relative weights of the rod signals within the three primary retinogeniculate pathways.

Support: Australian Research Council ARC-DP140100333.


1Visual Science Laboratories, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia2Laboratory for Retinal Physiology, Department of Ophthalmology, University Hospital Erlangen, Erlangen, Germany3Medical Retina Laboratories, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia4Queensland Eye Institute, South Brisbane, Australia

Andrew J Zele1, Amithavikram R Hathibelagal1, Jan Kremers2, Beatrix Feigl3,4

Invisible noise in the MC-, PC, and KC-pathways alters rod signaling in the mesopic range


SATURDAY 4 JULY

68

Objects typically have textures on their surfaces with various combinations of colors. Cortical area V4 plays important roles in color vision as well as in object recognition. Although many studies have examined color selectivity of V4 neurons, most have presented a single color patch in the receptive field (RF). Though some studies have reported that color selectivity is modulated by surrounding color in area V4 (Schein and Desimone 1990, Kusunoki et al., 2005), it is still not clear how single V4 neuron represents color combination.

We measured neural responses to combination of colors in V4. Two color patches were presented simultaneously in the RF of an awake fixating monkey. After identifying RF position/size, center-annulus stimulus was presented over RF. Stimulus size was set to cover both classical RF and surround. Colors of the center and the annulus were selected from 8 hues that evenly divided an iso-saturation circle in CIE-uv chromaticity diagram. For each neuron, we tested all combinations of 8 colors in the center and annulus. In addition, responses to single patch (either center only or annulus only) were tested. We found that about half of the V4 neurons tested showed strong modulation to color combination. These neurons responded strongly when specific combination of colors was presented on the center and annulus. Furthermore, in some neurons, such responses to specific color combination disappeared when colors were swapped between the center patch and annulus. This indicates that there is spatial specificity on the chromatic interactions. These results suggest that color combinations are represented in V4.

References 1. Schein SJ, Desimone R., Spectral properties of V4 neurons in the macaque., J Neurosci. 1990 Oct;10(10):3369-89.2. Kusunoki M1, Moutoussis K, Zeki S., Effect of background colors on the tuning of color-selective cells in monkey area V4., J Neurophysiol. 2006 May;95(5):3047-59.


1National Institute for Physiological Sciences, Okazaki, Japan 2SOKENDAI, Okazaki, Japan

Takahisa M Sanada1,2, Hidehiko Komatsu1,2

Neural response to color combinations in macaque area V4


MONDAY 6 JULY

69

PurposeThe difference in visually guided saccade latency reflects the difference in the properties of the stimulus (Gish, 1986). To dissociate visual processing pathway, it is necessary to control the properties of the stimulus related to its visual processing pathway. Satgunam (2005) has shown that saccade latency to isoluminance chromatic stimuli is longer than that to luminance achromatic stimuli. It is possible that this connects Pβ which connects to isoluminance response does not project directly to superior colliculus (Perry & Cowey, 1985). Prior studies, however, did not control the properties of chromatic stimuli sufficiently to determine cone responses. In our study, we investigated the difference between saccade latency to luminance stimuli and isoluminance chromatic stimuli, which were calibrated with the cone-isolate method (Donner and Rushton, 1959) to stimulate only the L-M or S system. We also investigated the relationship between stimulus intensity and detection threshold.

MethodWe tested 4 subjects with normal vision. The task involved detecting a Gabor patch. The subjects were asked to freely gaze at a 10° diameter Gabor patch at 10° eccentricity. Three experiment series were performed: luminance stimulus and isoluminance L-M and S stimuli. Each series had 5 spatial frequencies and 5 contrast conditions. The L-M and S stimuli can stimulate only the L-M and S system, respectively. We used a contactless eye tracker machine to measure the latency to the Gabor patch. We measured the detection threshold of each stimulus using the method of limits and investigated the relationship between saccade latency and stimulus intensity.

ResultWhen the stimulus intensity increased to a certain level, the latency settled under all conditions. The convergence differed depending on the stimulus series, and the latency to L-M and S stimuli was longer than that to luminance stimuli in all subjects.

ConclusionThe latency to L-M and S stimuli is longer than that to luminance stimuli, suggesting different pathways between luminance and L-M + S systems.


1Tokyo Woman’s Christian University, Japan2National Rehabilitation Center For Persons With Disabilities, Japan3Maeda Ophthalimic Clinic, Japan4The Jikei University School of Medicine, Japan5Kanagawa Rehabilitation Hospital, Japan

Aoi Takahashi1, Satoshi Nakadomari2, Ayumu Furuta3, Hiroshi Horiguchi4, Hiroyuki Kubo5, Koichi Oda1

Saccade latency to L-M and S contrast stimuli


SATURDAY 4 JULY

70

In order to achieve perceptual stability across saccadic eye movements, the visual system requires a remapping process in which the positions in the new retinal image are associated with the previous retinal image across a saccade. This mechanism still remains a mystery. A previous study has reported an illusion that provides an important insight into the mechanism of perceptual stability during saccades (Deubel, et al., 1998). In this illusion, observers have the impression that a distractor is stationary but the target is displaced after a saccade, although physically the distractor is displaced and the target is stationary during the saccade. This illusion is referred to as the ‘landmark effect’. We investigated the effects of luminance and isoluminance stimuli on the landmark effect. In the first experiment, we varied the luminance contrast of visual stimuli, and found that the strength of the landmark effect increases when the luminance contrast of the visual stimuli is low. In the second experiment, we used red-green isoluminant stimuli, and found that the landmark effect still occurs. These results suggest that a reduction in the transient signal of the saccadic target is critical to generate the landmark effect.


1Research Institute of Electrical Communication, Tohoku University, Japan2Department of Information and Media Engineering, University of Kitakyushu, Japan

Kazumichi Matsumiya1, Masayuki Sato2, Satoshi Shioiri1

Effects of luminance and isoluminance stimuli on perceived stability across saccadic eye movements: a study of the landmark effect


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71

Luminance channel had faster impulse response than red/green and blue/yellow opponent channels. It was thought that the process of luminance contrast was faster than those of chromatic contrast. Double-pulse temporal resolutions were studied by measuring the double-pulse distinguishing threshold (DPDT) at spatial frequencies 0, 2, and 8 cpd using psychophysical method at positive- and negative-luminance contrast conditions, red/green (stimulus/background) and green/red contrast conditions, and blue/yellow and yellow/blue contrast conditions by varying the chromatic coordinates of stimuli alone the directions of abscissa and ordinates axis in a physiologically-relevant LMS space. Both the stimuli and background luminance were 30 cd/m2 in all conditions except that the stimuli luminance was different to background luminance in luminance contrast conditions. A two-down-one-up staircase method was used to measure the DPDT. The double-pulse divided by various inter-stimuli-intervals was presented with about 6 ms temporal precision and less than 3% display error rate of luminance and chromatic coordinates in the LMS space. Thirteen observers with normal color vision were asked to judge how many flashes observed. The intensity of the single-pulse was the 95% detection threshold measured in previous experiment. Results showed that the DPDT of yellow/blue contrast were significantly lower than those of blue/yellow and luminance contrast. The result suggested that the double-pulse temporal resolution of yellow/blue contrast was higher than those of luminance contrast.

Acknowledgement: This study supported by National Natural Science Foundation of China (61368005).

Corresponding author: [email protected] University of Science and Technology, China

Lin Shi

Higher temporal resolution of isoluminance yellow/blue contrast than that of luminance contrast at same detection threshold level


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The structure of hue maps on the cortical surface of the monkey brain has begun to be revealed using optical imaging (Xiao et al., 2003, Nature, 421, 535–539). Recently Li et al., (2014, J. Neurosci, 34, 202–217) used this approach to describe topographic maps with dimensions of hue and lightness within colour selective subpopulations of V4. Such maps of colour space are yet to be identified in the human. Recent advances in high field strength fMRI are revealing fine-grained microstructures in the human that have previously been restricted to invasive techniques in the monkey. Yacoub et al., (2008, PNAS, 105, 10607–10612) presented oriented gratings at sequentially shifting orientations. The phase of the stimulus correlated BOLD response at the presented frequency was used to distinguish voxels with different orientation preferences and reconstruct the pinwheel organisation of V1.The current study aims to use 7T fMRI and a phase encoded mapping approach to reveal the topography of hue on the surface of the human visual cortex. We present colours sequentially from an isosaturated hue circle (9 equally spaced steps in CIELUV space). The visual field is filled with receptive field-size scaled patches at multiple lightness levels, shuffling rapidly while the colour is on the screen. Each colour is presented for 6 seconds, and the colours cycle 11 times in one 10 minute scan. The central 2o is masked with an attention demanding fixation task.We present preliminary data from two individuals showing coherence maps which are consistent across scanning sessions and participants, and are constrained to grey matter in visual cortex. Voxelwise hue selectivity maps in visual regions showing coherence with the stimulus cycling frequency are described. This method has the potential to reveal the structure of hue representations at multiple levels of the visual processing hierarchy for the first time in the human.Supported by ERC funded project ‘CATEGORIES’ (283605) to AF.


1The Sussex Colour Group, School of Psychology, University of Sussex, UK2Centre d’Imagerie BioMedicale (CIBM), Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

Chris Racey1, Weitske van der Zwaag2, Ryota Kanai1, Alex R Wade1, Anna Franklin1

The possibility of revealing chromatatopic maps in the human using 7T fMRI


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Unique hues (red, green, blue, yellow, and white) are considered as primaries of color appearance; intermediate colors can be represented as the combinations of the unique hues. On the other hand, cardinal axes of cone-opponent color space are considered to embody physiological basis for the representation of color signal in the early visual system. The purpose of the present study is to examine which is more essential to visual areas, between cardinal vs unique hues, by comparing brain activities to four hues (red, green, blue, and yellow for both types) in human visual cortex. fMRI images were obtained by BOLD (Blood-oxygenation level dependent) imaging technique. The color stimulus was presented as a check pattern (element size: 0.25 deg; radius: 3 deg), reversing between a hue and background gray at 2.5 Hz, for 3s and event-related responses were analyzed. The isoluminance of visual stimuli and the chromaticity of unique hues were adjusted for each subject, and the scaling between L/M and S-axes was equated by the multiples of detection threshold. The voxel resolution was 3 x 3 x 3 mm3 (TR=1.5s). Statistically significant difference was evaluated by averaging BOLD responses within each visual area. The significant difference was found only in V4; the response to unique hues was significantly larger than cardinal hues. Difference among hues was not statistically significant. If all color representations comprises the combined responses of cardinal-axis mechanisms, responses for unique green, which is in the intermediate direction of –L+M and –S axes, should be systematically greater than that for unique red, which is very close to the +L–M axis; however, this was not the case. Also, considering that functional mapping (e.g., motion-selective area) is defined by the superiority of response magnitude for essential (motion) vs non-essential (static) stimuli, our result may suggest that unique hues are more essential than cardinal hues at the level of V4.


1Graduate School of Information Sciences, Tohoku University, Japan2Research Institute of Electrical Communication, Tohoku University, Japan

Wakiko Maemura1, Ichiro Kuriki1,2, Kazumichi Matsumiya1,2, Satoshi Shioiri1,2

Differences in fMRI responses to cardinal and unique hues in human visual cortex


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Some researches suggested the interaction between colour and luminous signals in human visual system; luminance information is suppressed by colour information. We conducted two experiments using fMRI to reveal possible neural mechanisms of the suppression.

In Exp. 1, we measured brain activity while observing visual stimuli, which was manipulated in chroma value (0 (gray), 2, 4 and 6 in monitor-simulated Munsell colour system) of coloured patches. Visual stimuli consisted of 10 coloured patches in 10 hues on the achromatic background pattern. Brain activities of dorsal (V2d, V3d and V3A/B), lateral (LO1), and ventral (V2v, V3v and hV4) pathways and primary visual cortex (V1) were analyzed. The results showed that the brain activities were significantly lower in chromatic conditions (chroma value, 2, 4 and 6) than in the achromatic condition (chroma value, 0), in almost all of visual cortexes, suggesting that the brain activities driven by luminance information of the achromatic background pattern was suppressed by colour information.

We conducted the control experiment, in which the achromatic background pattern of the visual stimuli was replaced by a black screen, meaning that the brain activities would be driven only by coloured patches. The result of the control experiment indicated no significant difference between chroma value conditions, suggesting that the differences of the brain activities shown in Exp. 1 is not reflecting the differences of brain activities driven by isolated colour information.

In Exp. 2, we controlled the position of coloured patches to reveal spatial property of the suppression; whether the amount of the suppression retinotopically depends on visual fields concerning to hemispheres. If the suppression would depend on retinotopy, only brain activities of the hemisphere related to the visual field with coloured patches would be suppressed, and vice versa. The results showed that the suppression were not statistically different between hemispheres, supporting that mostly the suppression does not depend on retinotopy.

Supported by KAKENHI 24300085

Corresponding author: [email protected] University of Technology, Kochi, Japan

Ippei Negishi, Keizo Shinomori

Spatial property of luminous signal suppression by presentation of coloured patches


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Perceptual color is continuous, however we tend to divide the continuous color into several restricted categories. It is unclear whether categorical color perception is obtained solely through the development of the visual system or it is affected by language acquisition. In the present study, we measured changes in brain activity in relation to categorical color differences in prelinguistic infants (5- to 7-months old) by near-infrared spectroscopy (NIRS). We presented two sets of geometric figures to infants: one set altered the color between green and blue, and another set did between two different shades of green. Our results showed that the temporo-occipital region of infant brain represents the between- and within-category colors in a different manner. Hemodynamic responses during the between-category alternations showed significant increase, while that for the within-category alternations did not. Such asymmetric hemodynamic responses were not observed in occipital region. Hence the hemodynamic responses correlated with categorical color differences in the temporo-occipital region did not give rise to the low level color attributes such as color difference or salience. Similar hemodynamic responses to categorical color differences were also observed in adults. Through behavioral experiment by the habituation protocol, we confirmed that the colors used in the NIRS measurement could yield categorical differences in infants. The present study has obtained the first evidence that colors of different categories are differently represented in the visual cortex of prelinguistic infants, which implies possible achievement of categorical color perception through a developmental process in the visual system.


1Department of Psychology, Chuo University, Japan2Department of Psychology, Japan Women’s University, Japan3Research Institute of Electrical Communication, Tohoku University, Japan

Jiale Yang1, So Kanazawa2, Masami K Yamaguchi1, Ichiro Kuriki3

Cortical response to categorical color perception in infants investigated by near-infrared spectroscopy


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Berlin and Kay (1969)’s proposal of the eleven basic color terms has been demonstrated or confirmed by a number of research using color-naming methods with constraints such as ‘monolexemic’ color terms. We hypothesize the existence of additional important color categories represented by non-monolexemic color terms because some non-monolexemic color terms such as Kimidori (Ki-midori represents yellow-green in English) appear normally and frequently in Japanese language. Native Japanese speakers participated in the experiments and they named or expressed the 330 Munsell color chips from the WCS (World Color Survey) including 10 achromatic chips. Each participants performed two sessions, one is constrained color-naming session and the other is free naming session, basically as same as Lindsey and Brown’s (2014), with an exception that the participants were able to use both monolexemic and non-monolexemic color terms in the free naming task. In the constrained session the participants chose one of the eleven basic color terms for each color chip. In the analysis, we adopted two indices “consensus” and “consistency”, which Uchikawa and Boynton (1987) used to specify the locations of Japanese color categories. The free-naming results showed a total of 644 expressions and also some non-monolexemic expressions appeared commonly with high consensus; “Kimidori (yellow-green)”, “Fukamidori (dark-green)” and “Usumurasaki (pale-purple)”. Using the indices, we will discuss whether these three color expressions are universal, in order to investigate that these color categories are one of the important non basic color categories.


1Department of Information Design, Kogakuin University, Japan2Department of Information Processing, Tokyo Institute of Technology, Japan

Kazuho Fukuda1, Yumiko Muto2, Keiji Uchikawa2

Categorical color naming in Japanese without the constraint of monolexemic color terms


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【Introduction】Color processing includes color perception, color naming, and color knowledge. Previous neuroimaging and human lesion studies suggested that color perception was associated with the medial occipitotemporal region. The neural bases of color naming and knowledge remains to be solved, as patients with color knowledge impairment have rarely been reported.【Methods】Seven patients with occipital lesions participated in the study. Detailed neuropsychological examinations on color knowledge were given, including object-color knowledge and color naming. We also investigated knowledge of other properties of object (form, size, weight, and function). Using the 3T MR images, we analyzed the relationship between neuropsychological findings on color knowledge and lesion localization.【Results】One case presented color anomia, but fairly preserved color knowledge. Another case displayed specific impairment of object-color knowledge with normal color perception and object naming. He showed poor performance in various tasks tapping object-color knowledge, while his knowledge of object name, form, size and function were well preserved. Analysis of MR images revealed that the lesion in the left fusiform and lingual gyri was associated with color anomia, and that in the left fusiform, lingual and parahippocampal gyri with color knowledge impairment. Patients with the right fusiform and lingual gyri had no difficulties with color knowledge.【Discussion】Our findings suggest that object-color knowledge is dissociable from other properties of object knowledge. Furthermore, naming of color can be damaged independently of naming objects. These data support the notion that knowledge of color and that of other properties are represented autonomously. This study also provides evidence for a critical involvement of left medial occipitotemporal region in color knowledge.


1Department of Clinical Neuroscience, Yamagata University Graduate School of Medicine, Japan2Department of Neurology, Yamagata Prefectural Central Hospital, Japan3Department of Speech, Language, and Hearing sciences, Niigata University of Health and Welfare, Japan

Yuka Oishi1,3, Hikaru Nagasawa2, Naohiro Saito1, Kyoko Suzuki1

Neural bases of color knowledge in humans


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Some hues are more likely to be preferred than others (Palmer & Schloss, 2010, PNAS, 107, 8877-8882)). Some hues are also chosen as the best example of a given colour term (focal hues) and, as revealed by the World Colour Survey, these are common across speakers of different colour lexicons (e.g., Kay & Regier, 2003, PNAS, 100, 9085-9089). It has previously been suggested that patterns of adult hue preference and naming can be found in the variation in how long infants look at different hues (Bornstein, 1975, J Exp Child Psychol., 19, 401-419) Here we aim to investigate and quantify these proposed relationships, and we also examine the role of cone-contrast between the hue and background. Fourteen hues were sampled systematically from the Munsell stimulus array used in the World Colour Survey, all of equal lightness and at maximum chroma for any given hue. Two hundred 4-6 month infants were shown one of the hues repeatedly for eight 8 second trials, and looking time was measured. Infants’ average looking time across the hues was correlated with several measures: adult ratings of hue preference, the frequency with which hues were selected as focal colours in the World Colour Survey across languages; and L-M and S-(L+M) cone contrast between stimulus and background. Variation in infant looking time across hues was found to significantly correlate with how much adults like the hues (r =.67, p =.008) and how representative the colours are of colour terms (r =-.734, p =.003). S-(L+M) cone-contrast was related to both infant looking time (r =.63, p=.017) and adult hue preference (r=.69, p= .006): infants looked longer at hues, and adults preferred hues, with greater positive S-(L+M) cone-contrast. The findings suggest that there is a substantial contribution of low-level mechanisms of colour vision to both colour preference and colour naming.

Research was supported by a European Research Council Starting Grant (project “CATEGORIES”) 283605 (to AF).

Corresponding author: [email protected] of Sussex, UK

Alice E Skelton, Gemma Catchpole, Luke Wassell , Anna Franklin

Infants looking times to hues correlates with adult preference and how representative the colours are of colour terms


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Mean brightness of variegated regions can be an important clue to estimating illumination intensity over the regions as well as perceiving object lightness. Previously, we showed that mean brightness judgment for briefly-presented heterogeneous arrays of different luminance patches could be as accurate and efficient as simple brightness comparison for single patches, although it was slightly worse than brightness judgment for homogeneous arrays (Kimura & Takano, VSS2015). However, there remained possibilities that observers chose as the brighter array the one containing a highest luminance patch or the one having the larger total brightness. To rule out these possibilities, we used two arrays that were composed of different numbers of patches (6 vs. 12 or 9 vs. 12) on a dark background, and measured discrimination thresholds for mean brightness between the two arrays. Luminance conditions were designed to lead to highly biased thresholds, if observers relied on the highest luminance patch. Total brightness was unusable for comparing mean brightness of these arrays. Results showed that observers could still judge mean brightness in a reliable fashion, but a small bias was found for the array containing the highest luminance patch. This finding suggested brightness averaging with a greater weight on the highest luminance patch. Investigation with a higher background luminance produced qualitatively similar results, although the lowest luminance patch was the most salient in the stimulus arrays. However, when the instruction was changed from choosing the brighter to the darker array, the opposite bias for the lowest luminance patch was found for some observers. Overall, these results suggested that brightness of heterogeneous luminance patches is averaged not in a fixed, predetermined fashion, but flexibly and efficiently depending on the task and instruction.


1Graduate School of Humanities and Social Sciences, Chiba University, Japan2Department of Psychology, Faculty of Letters, Chiba University, Japan

Yusuke Takano1, Eiji Kimura2

Flexible brightness averaging for heterogeneous luminance patches


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Colour is composed of the perceptual dimensions of hue, lightness and saturation (or chroma). Burns and Shepp (1988) found using dissimilarity judgments that the perceptual dimensions of colour are not psychologically independent, in that participants could not always extract information from one dimension without ‘contamination’ from another. We aimed to investigate how the dimensions of colour interact when making colour judgments using the method of Maximum Likelihood Conjoint Measurement (MLCM). MLCM is a psychophysical procedure used to estimate the interaction of perceptual scales for stimuli distributed along two or more continua. Here, the perceptual scales were lightness and chroma. Sixteen colours at 4 levels of chroma and 4 levels of lightness for each of red, yellow, green and blue hues were defined. Participants judged all possible pairs of stimuli randomly selected from the 4x4 matrix. They were asked to decide which colour in the pair was lighter or more chromatic. The data were best fit by an additive model using MLCM which estimates the observers’ perceived lightness and chroma of colours as the additive contributions of underlying lightness and chroma responses. The contribution of the two dimensions differed between hues. For example, when judging the chroma of red, blue and green hues there was a negative contribution of lightness such that lighter colours were judged as less chromatic. However, when judging the chroma of yellow, there was a positive contribution of lightness such that lighter colours were judged as more chromatic. Linguistic explanations that relate to the position of the focal colours for each hue and perceptual explanations (e.g., the Bezold-Brucke effect) for the data are discussed. The broader potential uses of scaling methods to understand how dimensions of colour influence colour perception are also outlined. Research was supported by a European Research Council Starting Grant (project “CATEGORIES”) 283605, to AF.


1The Sussex Colour Group, School of Psychology, University of Sussex, Brighton, UK2Inserm U846, Stem Cell and Brain Research Institute, Department of Integrative Neurosciences, Bron, France3Université Lyon 1, Lyon, France

Marie R Rogers1, Kenneth Knoblauch2,3, Anna Franklin1

Using maximum likelihood conjoint measurement to establish the contributions of chroma and lightness to colour judgments


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Much work has been done to improve the assessment of light sources related with their color quality. One of the problems detected by traditional methods based on Color Rendering algorithm is related with LED sources. Subjective judgments made by real observers don’t correspond with values provided by these algorithms. In the case of LED light, generally a higher saturation of the colors in the scene occurs, resulting in a higher value of the score issued on the attractiveness of that source. Regarding the fidelity, the higher saturation is penalized in subjective judgments by comparing the scene with colors that would be perceived if natural light was used. In addition to this increased color saturation, a rotation of the chromaticity coordinates of the color components in the scene occurs too. But ¿is this rotation perceived by the subjective observers?A psychophysical hue scaling test has been done. We used NCS color samples with constant saturation and brightness attributes. This test was performed with four different light sources. As reference we used the memory of unique hues. That is, the observers assigned a value between 0 and 100 on a scale to each of the samples from each NCS quadrant considering that, for example, unique yellow was located at 0 and unique red occupied 100. The test was performed with 20 observers. The results reflect differences in mean ratings for each sample and each light source comparing with the original NCS values but never a widespread rotation of hue values unlike the algorithms for calculating the quality of light sources do. A method for discounting this rotation based on variations of unique hues depending on the color temperature of the light source is proposed.This work was supported by the Spanish Minister of Economy and Competitiveness, grant number FIS2013-40661-P, and by the Regional Government of Extremadura through the research groups fund program, partially financed by the European Regional Development Fund.


1Department of Computer and Network Systems Engineering, University of Extremadura, Centro Universitario de Mérida, C/ Santa Teresa de Jornet, 38, Merida, E06800, Spain2Department of Electronic and Electrical Engineering, University of Extremadura, Badajoz, Spain3Department of Physics, University of Extremadura, Badajoz, Spain

Pedro J Pardo1, Eduardo M Cordero2, Maria Isabel Suero3, Angel Luis Perez3

Unique hue correction applied to the color rendering of LED light sources


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Fluorescence is known as the emission of light by materials that has absorbed a light or other electromagnetic radiation, which is a form of luminescene. Perception of fluorescence occurs, however, not only to a fluorescent material but also a non-fluorescent material. This may relates to perceptual mode of color appearance. This study therefore proposes a hypothesis that the human visual system judges the perceptual fluorescence based on the optimal color, which refer to the physical limit of the luminance of a reflecting surface, and that certain illuminant spectrum is pre-assumed as daylight, not estimated from the input image, to calculate the optimal color. To test the hypothesis, psychophysical experiment was performed to measure the fluorescent color judgment under 27 achromatic illuminations with the same chromaticity and different spectra. Measured response probabilities for the perceptual fluorescence were fitted by a regression models with (1) simple luminance of stimuli, (2) optimal colors calculated by actual illuminant spectra, and (3) those calculated by pre-assumed daylight. As a result, coefficient of determination of the model using (3) pre-assumed daylight was significantly higher than other models, supporting the proposed "pre-assumed illuminant" hypothesis. In addition, we examined another hypothesis that perceptual fluorescence may relates with spatial luminance distribution of 3D objects. Fluorescent 3D objects may have less shadow than reflecting 3D objects because they emit light. We performed two psychophysical experiments with the pictures which were edited to decrease shadow of a 3D object. The first experiment was 2AFC task and observer judged which is more fluorescent. In the second experiment, observer estimated how fluorescent the object is. Observers were presented same set of pictures in each experiment. The results show that pictures with less shadow are easier to perceive as fluorescence.

Corresponding author: [email protected] University of Technology, Japan

Ryuji Katagiri, Shigeki Nakauchi

Perceptual fluorescence explained by optimal color depends on pre-assumed illuminant spectrum


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We can perceive gold in glossy surfaces with certain chromaticity ranges. It has been shown that contrast gloss and chromaticity of a surface are important factors for gold appearance. However, it is not sufficiently clear yet what image features are determining factors for gold appearance. We found that appearance of gold more strongly correlated with surface metallicity than glossiness (Matsumoto et al., VSS 2014). This result indicates that determining factors for gold appearance are similar to those for metallicity appearance of a surface. In the present study, we reanalyzed our data (Matsumoto et al., 2014 VSS) to investigate what factor of statistics of luminance distribution (mean, SD, skewness, kurtosis) of a surface relate to gold appearance. In experiments we simulated metallic and non-metallic objects (sphere, Stanford Bunny and 26-faceted polyhedron) by 3DCG as stimuli. Luminance of each pixel in metallic and non-metallic stimuli was morphed to make test stimuli with 6 different levels of contrast gloss. The luminance of each morphed image was multiplied to be different in luminance levels (5 levels). All pixels of the stimuli had the same chromaticity, which was obtained to make high degree of goldenness in our previous experiments. The observer performed the magnitude estimation of goldenness, metallicity and glossiness of the stimuli. The results showed that the estimates of gold and metallicity had the highest correlation with standard deviation of luminance distribution. This result suggests that standard deviation of luminance distribution is one of the determining features for the goldenness and metallicity.

Supported by KAKENHI 22135004 and 25245065.



Tomohisa Matsumoto1, Kazuho Fukuda2, Keiji Uchikawa1

Standard deviation of luminance distribution of an image significantly relates to gold appearance


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Humans discriminate gold from other materials by perceiving its surface appearance. Previous studies have indicated that gloss and color information influence the perception of the color termed “GOLD” (Okazawa et al., 2011; Komatsu et al., 2013). These studies usually used computer graphic images instead of real materials as stimuli. In this study, we further investigated the influence of surface physical properties and observation conditions on the material perception of gold using gold-like and gold-plated materials. For the gold-like materials, we used organic paints that can be cast into air-stable films with a gold-like luster (Tagawa et al., 2014). By varying the chemical formulation, many materials with differing gold-appearance were prepared. We investigated the influence of observation conditions through psychophysical experiments. The results indicated that the surrounding environment, light emitting area, and intensity of illumination affected the material perception of gold. In a natural environment, gold plated-material was perceived as gold rather than gold-like material. However, under some observation conditions, gold-like painted materials were perceived as gold even if genuine gold was not perceived as gold. Depending on whether materials were perceived as gold, we constructed a dataset comprising two categories of material images by varying the observation conditions. We measured the physical properties of materials such as bidirectional reflectance distribution function (BRDF), CIE xy chromaticity, and glossiness. The results confirmed that humans utilize color and gloss information to identify gold material. In particular, analysis of the chromaticity distribution of these images revealed that the material perception of gold was more related to the diffuse reflection than the highlight regions.

Okazawa, G., Koida, K., Komatsu, H. (2011). Categorical properties of the color term “GOLD”. Journal of Vision, 11(8), 1-19.Komatsu, H., Nishio, A., Okazawa, G., Goda, N. (2013). ‘Yellow’ or ‘Gold’?: Neural Processing of Gloss Information. Lecture Notes in Computer Science Volume 7786, 1-12.Tagawa, R., Masu, H., Itoh, T., Hoshino, K. (2014). Solution-cast self-assembled films of perchloratedoped oligo(3-methoxythiophene) showing a gold-like luster. RSC Adv., 4, 24053-24058.

Corresponding author: [email protected] University, Japan

Qi Zheng, Keita Hirai, Katsuyoshi Hoshino, Takahiko Horiuchi

Analysis of the material perception of gold using real objects


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85

Pterygium is wing-shaped, vascular and fleshy growth which encroaches from bulbar conjunctiva and progresses towards central cornea. Pterygium has been established as one of the factors which cause induced-corneal astigmatism, alteration of anterior corneal parameter, and changes in corneal topography. However, lack of research address the clinical agreement of subjective clinical grading based on its redness appearance, severity and properties of the tissue. Thus, this research aimed to assess both subjective and objective clinical agreement based on its redness appearance and mimic it with human color perception. In this research work, 68 pterygium fibrovascular images were captured in a standardized magnification and illumination. All images were stored in JPEG format and randomize sorted. The images were compared and graded based on reference images described in previous study by two observers. The time interval between intra and inter-session were set at least a month apart. Similar sets of images were used to mimic human color perception. Mimicking human color perception has commonly employed RGB color space, which is inadequate. When the CIELab features were extracted in various color space, it showed better representation of human perception (correlation coefficient = 0.68) compared to using vesselness filter (correlation coefficient = 0.43). This research work also found that for the subjective clinical grading, both intra-observer intraclass correlation (0.957, 95% CI: 0.930 – 0.973) (P = 0.001) and inter-observer (0.937, 95% CI: 0.898 – 0.961) (P = 0.001) shows excellent agreement respectively. In conclusion, this research work found that intra and inter-observer correlation were excellent, which proved that the individual variability is minimal in normal color perception. In addition, this research work also found that the CIELab can serve as a basis for future work on to automate pterygium clinical grading based on tissue redness which may reduce clinician bias and set a new standard for clinical pterygium assessment.


1Department of Optometry and Vision Sciences, Kulliyyah of Allied Health Sciences, International Islamic University Malaysia (IIUM), Kuantan, Pahang, Malaysia2Department of Ophthalmology, Kulliyyah of Medicine, International Islamic University Malaysia (IIUM), Kuantan, Pahang, Malaysia

Mohd Radzi Hilmi1, Mohd Zulfaezal Che Azemin1, Khairidzan Mohd Kamal2

Comparative analysis of subjective and objective clinical pterygium grading based on its redness appearance


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86

One of the color plates designed for tiredness of color vision could be found in K. Wang Color Vision Test Plates. They resemble the Ishihara plates but with richer color palete which provide chromatic masking of stimulus. Chromatic noise is widely applied for investigation of higher order color mechanisms and thus could be applied to look into the outcome of mental fatigue on perception of color. We attempted to use the chromatic noise paradigm to investigate the influence of the fatigue on chromatic detection. The test consists of 400 squares aligned in 20 by 20 lines and rows to present a square surface of static chromatic noise (Lucassen, Bijl, Roelofsen, 2007). Isoluminant colors of background and stimuli were selected in DKL color space and subtended around 20 ΔE saturation in CIELAB. Number of hues for masking noise background were changed through the experiment, either increasing or decreasing the number of hues in chromatic noise. At the beginning all background squares were composed of only 5 hues, then the proportion of colors increased continuously in the direction of stimuli hues. C letter stimuli consist of 52 squares was presented to participants with the task to identify the direction of stimuli opening. Two colors of 180 degrees difference were used as stimuli colors. Staircase procedure is applied to obtain the psychometric functions. Stimuli and mask were presented at the same luminance (21 cd/m2) gray background at 4 expositions of 41, 90, 166, and 793 ms. Subjective fatigue scale was recorded in 14 subjects after the extensive office work. We find a correlation between fatigue scale and reduction of noise thresholds mostly for brief stimuli exposures.

Supported by ESF No 2013/0021/1DP/1.1.1.2.0/13/APIA/VIAA/001.


1Laboratory of Visual Perception, Institute of solid State Physics, University of Latvia, Latvia2Optometry and Vision Science Department, University of Latvia, Latvia

Sergejs Fomins1,2, Gunta Krūmiņa2

Detection in chromatic noise and visual fatigue


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87

It is known that color contingent after effect occurs with some visual stimulus features or stimulus observing conditions. Bompas and O'Regan (2006) showed a sensorimotor contingency between directions of saccadic eye movements and observed colors. However, it might be the case that this color contingent after effect might occur with directions of visual attention shifts, not those of eye movements since visual attention always shifts with saccadic eye movements. In the present study we investigated contingency between attention shifts and color changes. In experiments there were three phases: base line test phase, adaptation phase and after adaptation test phase. In all phases, observers looked at the center of the screen. In the base line test phase and after adaptation test phase observers responded which stimulus appeared reddish (or greenish) between two stimuli presented in the center with the left and the right attention shifts. In the adaptation phase the red and green stimuli were presented in the center with the right and the left attention shift, respectively. The attention shift was caused by the exogenous square cue presented in the periphery. The test stimuli consisted of seven yellowish colors, chosen from in the line connecting the two adaptation red and green stimuli. The chromaticity difference between the first and second test stimuli, which yielded no difference in color appearance, was calculated from observer’s responses. We also carried out the same experiments, but using saccadic eye movements instead of attention shifts as reference experiments. It was obtained that the observers who showed color contingent effects with eye movements showed those effects with attention shifts. This suggests that attention shifts played important roles in the sensorimotor color contingent after effects.Acknowledgements: we thank Dr. Eskew for his valuable comments.


Department of Information Processing, Interdisciplinary Graduate School of Science and Engeneering, Tokyo Institute of Technology, Japan

Hiromi Yura, Keiji Uchikawa

Color contingent after effects with spatial attention shifts


SATURDAY 4 JULY

88

The phantom motion aftereffects (MAE), in which aftereffects can be expressed in areas of the visual field unadapted by motion, have been believed evidence for a hierarchy of a motion processing. To clarify whether chromatic information contributes to such a motion processing, we investigated chromatic radial phantom motion aftereffects. We tested the strength of the MAE by measuring the duration of the MAE as a function of temporal frequency of 1.0 to 16.0 Hz for 1.5 to 6 cpd-spatial frequency phantom stimuli. Our stimuli were 5-degree diameter-concentric rings with either sinusoidal luminance or chromatic profile. All normal color-vision subjects showed the phantom MAE regardless of spatial and temporal frequencies. However, the luminance phantom MAE lasted more than the isoluminat one. To confirm cross-interaction between luminance and chromatic motion mechanisms, we also tested whether these MAE occur under stimulus conditions that the test stimuli was the concentric ring with sinusoidal luminance profile and the reference was the isoluminat one, and vice versa.We found that the luminance stimuli produced the chromatic phantom MAE but not vice versa. These indicate that there is very weak motion signal produced by the first-order isoluminat stimulus is very weak and susceptible to preserving for a long time.

Corresponding author: [email protected] Institute of Technology, Japan

Tatsuya Yoshizawa, Toshihito Azumi

Radial phantom motion aftereffects by the isoluminat stimulus


MONDAY 6 JULY

89

It has been shown that the color discrimination threshold is the smallest at the adapted color, and the sensitivity to color difference at suprathreshold is the highest around the achromatic point. Meanwhile, under incomplete chromatic adaptation, an achromatic point does not coincide with the adaptation color. To investigate whether color discrimination and color appearance mechanisms share a common neutral chromatic point or not, we compared these properties under complete and incomplete chromatic adaptation conditions in the same subjects by using almost identical stimulus arrangement. We measured perceptual achromatic points, color discrimination thresholds, and suprathreshold color differences on the L-M axis under complete adaptation to an achromatic light (Gray condition) and incomplete adaptation to a chromatic light (Red condition). The color difference profile was examined by evaluating perceptual distance of various color pairs using maximum likelihood difference scaling (MLDS). In the Gray condition, the adaptation color appeared achromatic to subjects. In this case, chromaticities corresponding to the smallest threshold and the largest color difference were almost identical. In contrast, in the Red condition, the achromatic point shifted toward the origin of the color space (D65) from the adaptation color, indicating incomplete chromatic adaptation. In this case, the smallest threshold was achieved at the adaptation color, while the largest color difference was close to the achromatic point away from the adaptation color. Additionally, the sensitivity function derived from the discrimination data was narrower than that derived from the appearance data. Peaks of the sensitivity curves were systematically different between the adaptation conditions. These results suggest that the representation of color signal for the discrimination and appearance are mediated by separate mechanisms in a different form.


1Department of Computer Science and Engineering, Toyohashi University of Technology, Japan2Department of Informatics, Yamagata University, Japan3Research Institute of Electrical Communication, Tohoku University, Japan

Tomoharu Sato1, Takehiro Nagai2, Ichiro Kuriki3, Shigeki Nakauchi1

Dissociation of neutral chromatic points for color discrimination and color appearance under incomplete chromatic adaptation


SATURDAY 4 JULY

90

Perceptual brightness and color contrast is decreased after seeing a light temporally modulating along a certain direction in a color space. This phenomenon is called contrast adaptation. We investigated if contrast adaptation along the luminance direction arises from modulation of luminance signals or that of apparent brightness signals. The stimulus was two circles on a gray background presented on a CRT monitor. In the adaptation phase, luminance and color of one circle were temporally modulated, while the other was kept constant at a luminance and color metameric to an equal energy white. We employed two types of temporal modulations: luminance and brightness modulations. The chromaticity was sinusoidally modulated along the L-M axis, leading to dissociation between luminance and brightness (Helmholtz–Kohlrausch effect). In addition, luminance was kept constant in the brightness modulation, while brightness was kept constant in the luminance modulation. In the test phase, an asymmetric matching method was used to measure magnitude of contrast adaptation for both modulations. Our results showed that, although contrast adaptation along the luminance direction occurred for both modulations, contrast adaptation for luminance modulation was significantly stronger than that for the brightness modulation regardless of the temporal frequencies of the adaptation modulation. These results suggest that luminance modulation is more influential on the contrast adaptation than brightness modulation.

Corresponding author: [email protected] of Informatics, Yamagata University, Japan

Takehiro Nagai, Kazuki Nakayama, Yuki Kawashima, Yasuki Yamauchi

Contrast adaptation to luminance and brightness modulations


MONDAY 6 JULY

91

Illuminant estimation of a scene is one of the cues to reveal the color constancy mechanism. A variety of research has proposed the strategies of estimating illuminant color and some of them use scene statistics. We previously proposed the optimal-color hypothesis, in which the visual system selected the illuminant color so that its optimal-color surface best fit to the luminance-chromaticity distribution in the scene, and our psychophysical experiments supported this hypothesis (Uchikawa et al., 2012, JOSAA). In this study we formularized this hypothesis, then evaluated the model by comparing its illuminant estimations with the data obtained by psychophysical experiments. The model uses basically the common idea of the least square-error in order to chose the best-fit optimal color surface. As the data of psychophysical experiments , we used the results of our previous research, in which the participants set the chromaticity and luminance of a test patch so that it appears as a optimal white surface in each scene with natural and non-natural luminance distribution of surface colors (Uchikawa et al., 2014, ECVP and OSAFVM). The results showed a good correlation coefficient between the estimates by the model and the experiment in terms of both illuminant color and intensity, indicating the optimal color hypothesis gave a good model of illuminant estimation by the color constancy mechanism. We also discuss the validity of this model by compared it with other models.


1Department of Information Processing, Tokyo Institute of Technology, Japan2Department of Information Design, Kogakuin University, Tokyo, Japan

Takahiro Kusuyama1, Kazuho Fukuda2, Keiji Uchikawa1

Illuminant estimation using the optimal-color hypothesis on color constancy


SATURDAY 4 JULY

92

Most previous studies on color constancy have focused on effects of chromaticity change of a surface although both chromaticity and luminance of the surface vary when the illuminant changes. Thus, we have only a few psychophysical evidences which might show that visual system exploits change in luminance of surfaces to estimate an illuminant in a scene. Uchikawa et al. (2012) conducted experiments consisting of three conditions in order to investigate the contribution of luminance and chromaticity of the stimuli under different illuminants: (a) luminance-change only with constant chromaticity across illuminants (luminance-balance condition), (b) chromaticity-change only with constant luminance across illuminants and (c) luminance-change and chromaticity-change as normal. They found that the luminance-change only could contribute to color constancy, but its effect was smaller than other two conditions.

In this study we examined whether this relatively smaller luminance effect might come from small number of surrounding colors (only 6 colors). In order to address this question, we employed 60 surrounding colors to carry out their conditions. Four observers adjusted both chromaticity and luminance of the test region so that it looked as if a white paper was placed under a test illuminant.

For both 6 and 60 surrounding colors conditions, results showed that color constancy could work based on (a) luminance-change only although its effect was still smaller than (b) chromaticity-change only and (c) luminance-change and chromaticity-change. Also, better color constancy for 60 colors than 6 colors was shown for (b) chromaticity-change only and (c) luminance-change and chromaticity-change conditions. However, we found no significant effect of the number of surrounding colors on luminance-balance based estimation, suggesting that we could estimate illuminant even with small number of colors, which in turn proposes there would be influential colors to judge illuminants.



Takuma Morimoto1, Kazuho Fukuda2, Keiji Uchikawa1

Influence of the number of surrounding colors on luminance-balance based estimation of illuminant


MONDAY 6 JULY

93

A bright achromatic surround can turn a long-wavelength target from yellow to brown. However, in the real world, surrounding stimuli are more likely to have chromatic hues. Here, we begin to explore how chromatic surrounds influence the induction of brown. In the first study, a 4° diameter target was presented within an equiluminant 64 cd/m2 full-screen surround that was either achromatic or approximately unique blue, yellow, red, or green. Observers adjusted the luminance of the target to the boundary of brown, the light level where it turned from yellow-brown (butterscotch) to brown with no trace of yellow. We found that chromatic surrounds could either raise or lower the brown boundary level (an index of the strength of brown) relative to that found with the achromatic surround. Some of these effects are predicted by induction of opponent hues by chromatic surrounds: the blue surround strengthened brown, while the yellow surround weakened brown, presumably by inducing either brown/yellow or blue, respectively, into the target, which either reinforced or partially canceled brown, respectively. Other effects, especially with red or green surrounds, are still under investigation.

To provide a separate measure of the strength of brown induced by the chromatic surrounds, observers added B phosphor into the target until it looked achromatic gray, with no trace of brown. For the same surrounds, the pattern of the B cancelation amounts showed the same directions of effect as did the brown boundary settings: more B was needed to cancel brown on blue and green surrounds; less B was needed to cancel brown on yellow and red surrounds. Thus, both direct hue cancelation and brown boundary shifts shows the same general pattern of effects of chromatic surrounds on the strength of induced brown. Together, these results provide convergent validity that the effects of chromatic surrounds on the strength of brown are complex and only partially understood.

Corresponding author: [email protected] of Washington, USA

Luis Garcia, Tanner DeLawyer, Steven Buck

The influence of chromatic surrounds on perception of brown


SATURDAY 4 JULY

94

The perceived color of an object depends not only on the spectral composition of the light reflected from its surface, but also on the visual context such as illumination and surrounding colors. Compared to a neutral gray surround, a chromatic surround induces a change in the perceived hue of a stimulus. This shift in hue depends on the chromatic difference between stimulus and surround. We investigated how such induction of hue shifts varies with stimulus size. Subjects performed asymmetric color matching of chromatic patches across different isoluminant surrounds. Stimuli were defined in cone-opponent color space with hue corresponding to azimuth angle. Surrounds were either neutral gray, or had a chromaticity corresponding to one of eight hue angles with fixed cone contrast with respect to the neutral surround. Simulus size was varied between 0.5° and 8° of visual angle. As expected, induced hue shifts typically decreased with increasing stimulus size. However, quantitatively this decrease was different for different surround colors. In general, differences between induced hue changes by small versus large patches were larger for surrounds that induced large shifts, both in absolute terms and even when differences were expressed relative to the overall effect. That is, for surround hues that had a weak inducing effect, the relative change of the effect with stimulus size was smaller than for surround hues that had a strong effect. For surrounds with the strongest effects, induced hue shifts varied by a factor of up to 3.6 for the range of stimulus sizes tested. For specific surrounds, notably those for which induction was perpendicular to a blue-yellow axis corresponding to natural daylights, stimulus size had no significant influence on induction at all. The results indicate that stimulus size has a larger influence on hue induction for some regions in color space than for others.


1Department Biologie II, Ludwig-Maximilians-Universität Munchen, Germany2Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universität Munchen, Germany3Bernstein Center for Computational Neuroscience Munich, Germany

Christian J Kellner1,2, Thomas Wachtler1,3

Stimulus size dependence of hue changes induced by chromatic surrounds


MONDAY 6 JULY

95

Adapting to flickering black and white outlines of a shape defined by luminance contrast causes a decrease in that luminance and can cause the shape to disappear. This has been coined ‘contour adaptation.’ Previous observations also show that adaptation to black and white outlines does not seem to reduce the color contrast (desaturate) of colored shapes in the same way that it reduces luminance contrast. However there are instances wherein luminance and color interact in important ways such as the watercolor illusion. In this illusion the presence of simultaneous luminance and chromatic contrast in a border causes the color of the border to spread within the region enclosed by the border. It has been noted by others that the watercolor illusion is in part mediated by luminance dependent mechanisms. We have performed some experiments looking at contour adaptation and its effect on color and replicated the general finding that the adaptation is much more obvious with luminance contrast in the test pattern. However, we have found that the strength of illusory color spreading in the watercolor illusion does seem to be reduced by contour adaptation. This suggests that the luminance mechanisms that are reduced by contour adaptation play a role in modulating the strength of the watercolor illusion. Studying the effects of contour adaptation on the watercolor illusion may increase our understanding of how we perceive edges and how they contribute to the color of objects.

Corresponding author: [email protected] of Nevada Reno, USA

Andrew J Coia, Michael A Crognale

The effects of contour adaptation on the watercolor illusion


SATURDAY 4 JULY

96

We examined changes in appearance of real Munsell chips under different test illuminants with respect to a reference illuminant (C). Asymmetric sequential colour matching was used. Samples were viewed in a purpose-built viewing chamber. After appearing for 4 seconds under one of four test illuminants, individual test chips, were matched by one of sixteen chips under the reference illumination. Three colour normal observers and 2 different levels of chroma (8 and 4) were tested. The results were analysed on the u’-v’ chromaticity plane and compared with Ideal Observer computations for the 4 test illuminants; standard illuminant A, and three others referred to as S (high colour temperature) and 2 in the green (illuminant G) and purple (illuminant P) regions of colour space. In the majority of cases, lightness (value) appeared unchanged indicating high Lightness Constancy. Illuminant-induced chromaticity shifts were qualitatively predicted by our Ideal Observer model. The Chromatic Constancy Index was about 0.4 to 0.7. As shown classically, in general, the vectors describing the chromaticity shifts point towards the test illuminants. However, for illuminants S and A, subtle unpredicted variations corresponding to the Planckian Locus occurred. These effects were only evident when the line joining the test and reference iluminant lay along the Planckian Locus as is the case for A and S. Vectors for G and P illuminants were largely predicted by the Ideal Observer calculations. The data suggest that physiological factors influenced by the proximity of the Planckian Locus affect chromatic constancy under non-simulated viewing conditions.


1Faculty of Education, Lithuania University of Educational Science, Lithuania2Faculty of Life Sciences, University of Manchester, UK

Ausra Daugirdiene1, Janus Kulikowski2, Ian Murray James2, Jeremiah Kelly2

Test illuminant location with respect to Planckian Locus affects chromaticity shifts of real Munsell chips


MONDAY 6 JULY

97

The saturation of visual scene decreases depending on haze due to environments and optical properties of eyes (e.g. fog, aging of crystalline lens). However, we may not perceive the change in saturation as much as it actually does, if compensation mechanisms similar to those for other aspects of color work. We investigate how colorfulness perception changes by haze to clarify if we can maintain stable colorfulness perception of a scene. First, we examined the influence of adaptation time to haze on the natural colorfulness range of an image. Observers adapted to haze by observing natural images through foggy filters. After 0 sec to 180 sec adaptation, they made judgments of colorfulness of test images with various saturation levels. Then, we obtained the range of saturation for each test image to appear natural. As a result, even immediately after wearing in the foggy filters, the observers responded almost the same with and without the foggy filters, and the influence of adaptation time to the haze on colorfulness perception was very weak. Next, we used a saturation matching method to further examine if the stable colorfulness appearance with the foggy filters were not due to the criterion of natural range but perceptual compensation. We tested a condition viewing natural images through the actual foggy filters as well as simulated images. For the condition using the foggy filters, observers adjusted the saturation of a natural image through the foggy filters to match the colorfulness appearance of natural images which they had memorized without the filter. Time for the adjustment was limited to 5 seconds to avoid the influence of adaptation to haze. Results again show that the saturation setting with the filters was almost the same as those without the filter. These results suggest that we can adjust our perception to decreased saturation by the haze and maintain stable colorfulness perception. Supported by JSPS KAKENHI Grant Number 40436340.

Corresponding author: [email protected] School of Advanced Integration Science, Chiba University, Japan

Yuki Takahashi, Yoko Mizokami, Hirohisa Yaguchi

Colorfulness perception of natural images adjusting to haze


SATURDAY 4 JULY

98

The streetlamps employed at nigh lighting conditions produce luminance levels within the mesopic range. Usually, the visual performance in these conditions is analysed by using models for mesopic spectral sensitivity that consider different factors such as the luminance and the chromaticity of the visual scene, the retinal location and the type of illuminant. However, all these models have been developed from measurements performed on young subjects.

In this study, we have analysed the effect of age and type of illuminant on the achromatic contrast detection thresholds. Measurements have been performed with a double Maxwellian view optical system. Three age groups, young, mid-age and old and two different light sources (metal halide MH, S/P = 1.17), and high pressure sodium HPS, S/P = 0.48), two retinal locations (fovea and 10º), and four background luminances (Lb = 0.01, 0.07, 0.45, and 3.4 cd/m2) were considered.

In eccentric vision and Lb = 0.01 cd/m2, contrast sensitivity was higher with HPS than MH in old-age subjects, while this situation is opposite to young subjects.

In these conditions, adaptation and detection are governed by rods. In young subjects, the higher spectral sensitivity of rods to shorter wavelengths produces lower contrast detection thresholds for MH lamps than for HPS lamps. Opposite, in the old age group, the increase in the straylight due to the prereceptoral media aging produces an important increment in contrast detection threshold. This increment is particularly observed at very low Lb where rods are very sensitive; while at higher Lb, the effect is not so significant since detection is mostly due to cones. The directional sensitivity of these makes them less sensitive to intraocular scattering. We can conclude that the influence of age on contrast detection thresholds seems to be different for the two compared lamps type within the mesopic range. Therefore, the age should be included as a parameter in mesopic vision models.


1Departamento de Óptica, Universidad de Valladolid, Valladolid, Spain2Instituto de Luz, Ambiente y Visión, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina3Departamento de Estadística eInvestigación Operativa, Universidad de Valladolid, Spain

Isabel Arranz1, Matesanz M Beatriz1, Issolio Luis2, Silva Barbara2, Colombo M Elisa2, Menéndez A José3, Mar Santiago1, Aparicio A Juan1

Influence of age on contrast threshold detection for urban lamps with different spectral distribution in the mesopic range


MONDAY 6 JULY

99

Color perception is known to remain largely stable across the lifespan despite the pronounced changes in sensitivity from factors such as the progressive yellowing of the lens with age. However, the mechanisms and timescales controlling these compensatory adjustments are still poorly understood. We tracked adaptation in observers after introducing a sudden change in “lens” density, by having observers wear glasses with yellow filters that approximate the average spectral transmittance of a 70-year-old lens. Individuals were young adults and wore the glasses for 5 days for 8 hours per day while engaged in their normal activities. Achromatic settings were measured on a CRT monitor before and after each daily exposure with the glasses on or off, and were preceded by 5 minutes of dark adaptation to control for short-term chromatic adaptation. During each day there was a large shift in the white settings toward the pre-adapted white point, consistent with a partial compensation for the added lens. Much of this dissipated when the glasses were removed, yet over repeated days there was also a gradual drift in most observers’ white points, again toward the pre-adapted white point, consistent with evidence for a longer-term renormalization for the yellow lens (Delahunt et al. Visual Neuroscience 2004). Preliminary results suggest that these perceptual changes are accompanied by shifts in the null stimulus for short-term chromatic adaptation, suggesting that at least part of the sensitivity adjustment reflects changes at or before the loci controlling conventional chromatic adaptation. Supported by EY-10834 (MW) and AG-04058 (JW)


1Department of Psychology, University of Nevada, Reno, USA2Department of Ophthalmology & Vision Science, University of California, Davis, USA

Katherine EM Tregillus1, John S Werner2, Michael A Webster1

Adjusting to an aging lens


SATURDAY 4 JULY

100

Purpose: To compare the colour thresholds measured using newly developed custom designed iPad application (app) with the Cambridge Colour Test (CCT: Trivector test).Methods: An iPad application with two games was developed to assess colour sensitivity. The design of both the iPad games is similar to the children friendly version of CCT Trivector test with the addition of few fun elements (feedback, scores and sounds) to iPad game2. The colour thresholds for Red-Green (average of Protan and Deutan in Trivector test) and Blue-Yellow (Tritan in Trivector test) were measured for twenty normally sighted subjects with the age range of 18-51yrs, using Trivector test followed by two iPad games. Testing was done binocularly and Paired t-test was used to compare colour thresholds obtained using iPad games with that of the Trivector test.Results: The results showed no significant difference in colour thresholds between Trivector test and iPad game1 (Red-Green: t19= –1.64, p > 0.05, Blue-Yellow: t19= –1.38, p > 0.05) or game2 (Red-Green: t19= –0.58, p > 0.05, Blue-Yellow: t19= 0.71, p > 0.05). Both the iPad games showed comparable results with that of the Trivector test.The mean ± SD colour thresholds (10−4 u’v’ Units) for Trivector test for Red-Green and Blue-Yellow were 39 ±2 and 59 ±22; corresponding results for iPad game1 were 45 ±14 and 66 ±18 and for iPad game2 were 41 ±12 and 55 ±14. The mean difference between Trivector and iPad game1 were –6 ±16 and –7 ±23 and; between Trivector and iPad game2 were –2 ±15 and 4 ±26 for Red-Green and Blue-Yellow, respectively.Conclusion: The newly developed custom designed iPad app with two games for measuring colour thresholds showed comparable results with that of the CCT Trivector test. Considering the validation, fastness and portability, the iPad app could be considered as an alternative to the existing measures of colours sensitivity.Key Words: Colour sensitivity, Trivector test, iPad, iPad application, iPad games

Corresponding author: [email protected] of Optometry and Vision Science, University of New South Wales, Sydney, Australia

Lakshmi Bodduluri, Mei-Ying Boon, Stephen Dain

An iPad application to test colour sensitivity


MONDAY 6 JULY

101

The study aimed to elucidate the association between the color discrimination ability and the brain activity. We investigated steady-state visual evoked potential (SSVEP) of the brain in subjects with normal and any color vision deficiencies. In an experiment, the subjects were instructed to gaze into 3 flickering stimuli (red-green, blue-yellow and achromatic) for 5 seconds. The colors of the pairs used in the stimuli were not distinguishable by protanopia and tritanopia people, respectively. Flickering frequency (f) of these stimuli was set to 2, 3, 4, 5 or 10 Hz in each experiment session. Their average luminance and apparent size were 65 cd/m2 and 10 degrees. Electroencephalograms (EEGs) were measured at 8 loci (POZ, 3, 4, 7, 8 and OZ, 1 ,2) on the back of the head over the visual area of the brain. Power spectral densities were calculated from the measured EEGs by using a frequency domain analysis. We found SSVEPs with sharp peaks at the fundamental (f) and its harmonics (2f and 3f) frequencies in all the subjects. In the case of normal subjects, the amplitude curve of the SSVEPs formed a bandpass shape, which the vertex was at 3 or 4 Hz. The SSVEPs elicited by the red-green flickering stimulus were consistently larger than the blue-yellow stimulus. Interestingly, the SSVEPs of the color blind subjects were different from the normal subjects. For example, in the case of a deuteranomaly subject, the SSVEPs elicited by the red-green stimulus were about 60% smaller at 3, 4 and 5 Hz than the average SSVEPs of the normal subjects. The SSVEPs elicited by the blue-yellow stimulus were about 150% larger at 4 and 5 Hz. These results suggested that SSVEP could be influenced by color discrimination ability of individuals. We believe that this finding leads to establish a novel, brain-based functional diagnostic technique for color discrimination ability.


1Aisin Cosmos R&D Co., Ltd., Japan2Toyohashi University of Technology, Japan

Hideaki Hirose1, Shigeki Nakauchi2

Steady-state visual evoked potentials reflecting color discrimination ability of individuals.


SATURDAY 4 JULY

102

One of the barriers to the construction of consistent computer-based colour vision tests has been the variety of monitors and computers. Consistency of colour on a variety of screens has necessitated calibration of each set-up individually. Colour vision examination with a carefully controlled display has, as a consequence, been a laboratory rather than clinical activity. Inevitably, smart phones have become a vehicle for colour vision tests. They have the advantage that the processor and screen are associated and there are fewer models of smart phone than permutations of computers and monitors. Colorimetric consistency of display within a model may be a given. It may extend across models from the same manufacturer, but is unlikely to extend to between manufacturers especially where technologies vary.In this study we measured the same set of colours in a jpeg file displayed on 11 samples of each of 4 models of smart phone (iPhone 4S, iPhone5, Samsung Galaxy S3 and Samsung Galaxy S4) using a Photo Research PR-730. The iPhones are white LED backlit LCD and the Samsung are OLEDs.The colour gamut varies between models and comparison with sRGB space shows 61%, 85%, 117% and 110% respectively. The iPhones differ markedly from the Samsungs and from one another. This indicates that model specific colour look–up tables will be needed. Within each model the primaries were quite consistent (despite the age of phone varying within each sample). The worst case in each model was the blue primary, the 95th percentile limits in the v’ coordinate were ±0.008 for the iPhone 4 and ±0.004 for the other three models. The u’v’ variation in white points was ±0.004 for the iPhone4 and ±0.002 for the others although the spread of white points between models was u’v’ ±0.007. The differences are essentially the same for primaries at low luminance. The variation of colours intermediate between the primaries (eg red-purple, orange) mirror the variation in the primaries. The variation in luminance (maximum brightness) was ±7%, 15%, 7% and 15% respectively. The iPhones have almost 2x the luminance. To accommodate differences between makes and models, dedicated colour look-up tables will be necessary, but the variations within a model appear to be small enough that consistent colour vision tests can be designed successfully.

Corresponding author: [email protected] of Optometry and Vision Science, University of New South Wales, Australia

Stephen J Dain, Benjamin Kwan, Leslie Wong

Consistency of colour representation in smart phones


MONDAY 6 JULY

103

We usually recognize color by two kinds of processes. In the first, the color is recognized continually and a small difference in color is recognized. In the second, the color is recognized discretely. This process recognizes a similar color of a certain range as being in the same color category. The small difference in color is ignored. Recognition by using the color category is important for communication using color. It is known that a color vision defect confuses colors on the confusion locus of color. However, the color category of a color vision defect has not been thoroughly researched. If the color category of the color vision defect is clarified, it will become an important key for color universal design.In this research, we classified color stimuli into four categories to check the shape and the border of the color categories of varied color vision. The experimental result was as follows. The border of protanopia is the following three on the CIE 1931 (x, y) chromaticity diagram: y = -0.3068x + 0.4795, y = -0.1906x + 0.4021, y = -0.2624x + 0.3896. The border of deuteranopia is the following three on the CIE 1931 (x, y) chromaticity diagram: y = -0.7931x + 0.7036, y = -0.718x + 0.5966, y = -0.6667x + 0.5061.


1Kogakuin University, Japan2Cudo

Yasuyo G Ichihara1,2

Clarifying color category border according to color vision


SATURDAY 4 JULY

104

PURPOSEIn 2003, color vision screening (using Ishihara Test) was excluded from mandatory requirements of the school medical examination in Japan. Since then, almost 10 years have past and there are some reports about troubles caused by the student's unawareness of the congenital color vision deficiencies. This study aims to investigate experiences and consciousness of teachers about students' congenital color vision deficiencies.

METHOD148 teachers participated in the license renewal lectures for teachers answered a simple questionnaire about congenital color vision deficiencies. Before answering it, they took a short lecture about congenital color vision deficiencies and Ishihara Test.

RESULTSFor the knowledge about congenital color vision deficiencies, 83 % answered "They have a difficulty for red or green colors". It suggested that most of teachers had a simple knowledge about congenital color vision deficiencies. Teachers who had experience about teaching students with congenital color vision deficiencies were 17 %. But it was also considered that other teachers were not able to notice the existence of such students in the classroom. 6 % had experience that student who had congenital color vision deficiencies faced problems in finding a job. Such student had to change the place of employment. In addition, 43 % supported Ishihara Test for the method to assess students' color vision.

Corresponding author: [email protected] University of Education, Japan

Nobuyuki Nagai

Experiences and consciousness of teachers about congenital color vision deficiencies of students


MONDAY 6 JULY

105

Recent research has studied colour preference in people with normal colour vision (normal trichromacy). The current study investigates colour preference in males with red-green dichromacy, which is a genetic condition affecting 2% of males where a cone photoreceptor is missing (L cone in protanopia; M cone in deuteranopia). Normal trichromat males and females (N=32) and males with protanopia and deuteranopia (N=32) rated their preference and named 35 colours which were classified in four different sets: focal, saturated, light and dark. Normal trichromats showed the same pattern of colour preference found in previous research: preference maxima in blue, preference minima in yellow-green. Both protanopes and deuteranopes had reliable colour preference patterns but different from trichromats, with a preference maxima rather than minima at yellow and a much weaker preference for blue than trichromats. The protanopes were more different to the trichromats in their pattern of preference than the deuteranopes were. A cone-contrast model with the red-green and blue-yellow mechanisms (Hurlbert & Ling, 2007, Curr Biol, 17, R623) effectively summarized normal trichromat preferences (up to 99.5% of variance explained). The yellow-blue mechanism could also summarize protanopia and deuteranopia preferences (up to 87.7% explained), and residual red-green activity also appeared for deuteranopes. Speed and consistency of colour naming accounted for up to 50% of the variance in the pattern of colour preference of red-green dichromats and normal trichromat males, but not for females. The findings provide novel evidence on how red-green dichromats experience colour, as well as further advancing our understanding of human colour preference.

Support: A Universidad Complutense de Madrid research fellowship BE48/09 (to LA), a European Research Council Starting Grant (project “CATEGORIES”) 283605 (to AF) and a Ministerio de Economía y Competitividad grant PSI2012-37778 (to JL, HM, LA).


1Facultad de Psicología, Universidad Complutense de Madrid, Spain2School of Psychology, University of Sussex, UK3The Sussex Colour Group, University of Sussex, UK

Leticia Álvaro1, Humberto Moreira1, Julio Lillo1, Anna Franklin2,3

Colour preference in red-green dichromats


SATURDAY 4 JULY

106

In Japan, there are more than three million people are red-green color deficient, which is not a negligible number. Therefore, color design considering these people is important. In our previous study, Chen et al. proposed the way of color enhancement for congenital red-green color deficiency based on Mochizuki et al.’s model with the aim of facilitating color customization in displays used by those observers. Three types of color enhancements were examined in their study. First, colors were enhanced along the protan confusion line, i.e., P-enhancement. Second, colors were enhanced along the deutan confusion line, i.e., D-enhancement. Third, colors were enhanced along a line between the protan and deutan confusion lines, i.e., mix-enhancement. Their criterion was a preference of color tone in the displayed image, i.e., KANSEI evaluation. Results showed that color enhancement increases the preference evaluations of protan and deutan observers. It is worth noting that for color normal observers, these color enhancements were also effective, although the degree of enhancement was smaller than those of color deficiencies. Results of Chen et al.’s indicate that every observer has his/her own preferred color tone for displayed images. So, it would be convenient if one can choose his/her best way of color enhancement easily by doing a simple test. The aim of this study is to select the best benchmark image to determine the type and degree of color enhancement that gives the most preferable color tone for each individual observer.In the experiment, four color images were selected as benchmark candidates in the pre-experiment, 3 types, 5 degrees of enhancement for each of them. At the present, preference tendency of color normal observers is being investigated. After choosing the way of enhancement (type and degree) for each benchmark, their effectiveness is to be assessed using 300 test images. Similar experiment will be done for color deficiencies.


1Department of Advanced Interdisciplinary Sciences, Graduate School of Engineering, Utsunomiya University, Japan2none

Taku Goto1, Tomoharu Ishikawa1, Kazunori Asada2, Miyoshi Ayama1

Benchmark to select a preferable color enhancement for an individual observer


MONDAY 6 JULY

107

Introduction: Grapperon (2004) reported that color defective (CVD) individuals were slower to respond to all stimulus categories in a Stroop experiment that used red, green, and blue as the stimulus colors. Nevertheless, the interference effect (i.e., incongruent font color and color name) was similar for the CVD and the color normal (CVN) groups. We replicated and expanded our experiment to include mild hypoxic environments, using three colors that were less likely to be confused by the CVD group. Methods: Reaction times and correct responses were recorded for the Stroop test included in the ANAM.4TM cognitive test battery. The colors were a different set of red, green, and blue in which the luminances were higher than used by Grapperon. The test was administered at ground (i.e., 394 m), simulated 3,780 m, and 20 min after returning to ground. Twelve CVN individuals and 17 CVDs participated.Results: A significant interaction (p=0.03) between altitude, an age factor (<35 yrs or >35 yrs), and color vision status along with a significant interaction between color vision status and stimulus subsets (p=0.047) indicated that the findings were complex. The older CVD subjects were slightly slower than the older CVN group; except after returning to ground where the CVD mean reaction times were faster. The mean reaction times for the younger CVD subjects were always faster than younger CVN subjects, especially at 3,780 m. The interference values averaged across all altitude conditions for the CVD subjects were significantly lower (p=0.04). Error rates for the two subject groups were similar across all conditions. Conclusions: If the colors used in the Stroop experiment are easily distinguishable for CVD individuals, then there may not be any delays in identifying the colors. Interference may also be less, which suggests that CVD subjects benefit more from the list level congruent effect that is present when the Stroop stimuli are presented sequentially.


1School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada2FAA Civil Aerospace Medical Institute Oklahoma City, OK, USA

Jeffery K Hovis1, Nelda J Milburn2, Thomas E Nesthus2

The stroop effect, color vision deficiencies, and mild hypoxia


SATURDAY 4 JULY

108

Spot color ink generated by mixing base inks is able to produce the variation of color with different reflectances, and it has been used more often than cmyk process ink in package printing industry. In particular, the appearance of red color ink is important for both designability and visibility as it is often used for notes on many packages. We are able to create spot color inks to reproduce metameric colors that appear the same chromaticity with different spectral distributions by selecting the base ink combinations. It would be possible to provide a new recipe for red color ink with improved visibility. Here, we examine base ink combinations to achieve conspicuous red for various illuminant conditions and color vision deficiency. We made various red spot color inks which consisted of several base inks, and printed on coated papers using those spot color inks. Observers with normal color vision and color vision deficiency evaluated the redness of the printing samples and their discriminability from a black background under two illuminance levels (500 lx and 1 lx). The results show that the evaluation of the redness for samples with high chroma and from 2.5R to 7.5R in Munsell hue is high at 500 lx in general. At 1 lx, however, observers with color vision deficiency, especially protan, evaluated the redness higher for samples with high chroma and yellowish red hue. The result of discriminability from black shows the larger influence of lightness at 1 lx than at 500 lx. Samples with high chroma are highly discriminable for both normal and deutan observers. Those with yellowish red hue and high chroma are more discriminable for protan observers at 1 lx, similar to the results of redness. Better discriminability for those samples would be due to the higher middle-wavelength components in the spectral reflectance of those samples. This suggests that it is possible to improve the visibility of red ink by controlling base ink combinations.


1DIC Corporation, Japan2Graduate School of Advanced Integration Science, Chiba University, Japan3DIC Color Design, Inc., Japan

Masami Shishikura1, Terumi Kato2, Yoko Mizokami2, Shinichiro Taniguchi1, Tomomi Takeshita3, Fumiko Goto3, Hirohisa Yaguchi2

Color appearance of red printing ink with various spectral reflectances for color vision deficiency


MONDAY 6 JULY

109

Punjab is the largest province of Pakistan according to population proportion. The prevalence of consanguinity in the Punjab is 80 percent. Due to high rate of cousin marriages, hereditary diseases are more common in various ethnic population groups inhabiting different districts. In the current study, it is planned to study genetic epidemiology of colour-blindness in relation to consanguinity and ethnic / isonym groups. Till date in the district of Chiniot, survey for colour-blindness has been done in two out of three tehsils (administrative subdivision of the district). It is the first population based study on colour-blindness in Punjab, as well as in Pakistan. Chiniot is a city of the central Punjab, with a history ranging from 326 BC, the arrival of Alexander, the Great. It has a well diverse population consisting of 15 principal tribes. The objective of the study was to find out prevalence of colour-blindness and its association with different risk factors. Defined age group of study is 14 years to 18 years of age students of Higher Secondary Schools. According to current data, prevalence of colour-blindness in males is 3.84% while no colour-blind female has been found in two tehsils. The third tehsil is under investigation. All the colour-blind cases found so far in two tehsils, fall under consanguinity. However, 80% of which were due to first and second cousin marriages. To see association of colour-blindness with consanguinity and to study its genetic epidemiology, pedigrees of colour-blindness cases have been prepared. After the completion of this pilot investigation in the district of Chiniot, we intend to extend this study in other districts of the Punjab, to find out the incidence of colour-blindness in different ethnic groups inhabiting the Punjab, Pakistan.


1University of Health Sciences Lahore, Pakistan2Gulab Devi Postgraduate Medical Institute Lahore, Pakistan

Muhammad S Akhtar1,2, Asif Hanif1,2, Muhammad Aslamkhan1

Preliminary report of colour-blindness in the Punjab, Pakistan


SATURDAY 4 JULY

110

Color-vision deficient (CVD) observers who have dichromatic characteristics cannot discriminate among red-green hues. Nevertheless, they can name colors as accurately as normal trichromat (NT) observers. The color naming mechanism, called categorical perception of colors, has been studied by many research groups using color chips. We now study the categorical perception of color on a monitor by CVD observers for application to image processing of the color universal design system. This study aimed to compare color-naming characteristics of CVD observers with those of NT observers and investigate color impression as basic research.This experiment used 68 color stimuli which ware sampled at u'v' coordinates at three different brightness levels (8, 32, and 56 cd/m2). In the color-naming task, four CVD and four NT subjects selected one color category among 11 basic color terms (Red, Pink, Orange, Yellow, Green, Blue, Purple, Brown, Black, Gray, and White), and an unknown category. In the evaluation task for color impression, the same subjects evaluated color impression using 6 adjectives with 7 points along a bipolar scale. We used the multidimensional scaling (MDS) method to construct color categorization space and calculated the correlation coefficient between the MDS dimensions and a*b* features representing reddish-greenish and blueish-yellowish axes, respectively. To compare color impression of the CVD subjects with those of the NT subjects, we applied the principal component analysis to the impression values of all subjects. We found that the responding numbers of CVD subjects for the green category in the color naming task was larger than those of NT subjects at all brightness levels. This result was in accordance with previous findings using color chips. Next, for both CVD and NT subjects, each color categorization space was described in two dimensions. In NT subjects, the first and second dimensions corresponded to reddish-greenish or blueish-yellowish axes at all brightness levels. However, in CVD subjects, the relationship between the second dimension and chromatic feature was not clear. Finally, color impression space was presented in two dimensions. The color impression distribution of CVD subjects was much smaller than that of the NT subjects.


1Kagawa University, Japan2Okayama Prefectural University, Japan3Keio University, Japan

Keiko Sato1, Hironori Takimoto2, Yasue Mitsukura3

Color naming properties and color impression of subjects with deficient color-vision at different brightness levels


MONDAY 6 JULY

111

AAher, Avinash　4Akhtar, Muhammad S.　109Alfaro, Catarina　46Almeida, Vasco MN　18Álvaro, Leticia　18, 105Amano, Kinjiro　46Amos, Nikki　41Ansari, Imran　23Aparicio, Juan A.　66Arikawa, Kentaro　11Arranz, Isabel　66, 98Asada, Kazunori　106Aslamkhan, Muhammad　109Atorf, Jenny　5Auer, Tibor　60Ayama, Miyoshi　106Azumi, Toshihito　88

BBachy, Romain　51Bailão, Ana　46Baraas, Rigmor C.　30, 56Barbara, Silva　98Barbur, John L.　20, 23, 34Barrionuevo, Pablo A.　13, 66Beatriz, Matesanz M.　98Bimler, David L.　41, 42Bloj, Marina　38Bodduluri, Lakshmi　100Bonnardel, Valérie　41, 42Boon, Mei-Ying　100Bosten, Jenny M.　10Brown, Angela M.　40Buck, Steven L.　9, 49, 50, 93

CCanning, Chris　23Cao, Dingcai　13Carroll, Joseph　17, 24, 36Catchpole, Gemma　39, 78Che Azemin, Mohd Zulfaezal　85Cheong, Soon Keen　59Christiansen, Jens　43Coia, Andrew J.　95Collison, Frederick　24Cordero, Eduardo M.　81Crognale, Michael A.　95

DDain, Stephen J.　100, 102Danilova, Marina　61Daugirdiene, Ausra　96de Almeida, Vasco MN　35DeLawyer, Tanner　49, 50, 93Devinck, Frédéric　58Dojat, Michel　58Downey, Colin O.　62Dreher, Bogdan　59D'Souza, Dany　60Dubra, Alfredo　24

EElisa, Colombo M　98

FFeigl, Beatrix　67Fishman, Gerald　24Fomins, Sergejs　86Forder, Lewis　47Frahm, Jens　60Franklin, Anna　39, 44, 47, 72, 78, 80, 105Freitas, Maria H.　46Fukuda, Kazuho　31, 40, 76, 83, 91, 92Furuta, Ayumu　69

GGarcia, Luis　93Gegenfurtner, Karl R.　38Gerardin, Peggy　58Gilson, Stuart J.　30, 56Gloriani, Alejandro H.　66Goto, Fumiko　108Goto, Taku　106Gunther, Karen L.　62

HHagen, Lene A.　30, 56Hanif, Asif　109Hathibelagal, Amithavikram R.　67Hauswirth, William　24Heath, Louise　41Hertig, Vonnik　42Hickey, Joseph D.　20, 34Hilmi, Mohd Radzi　85Hirai, Keita　84Hirose, Hideaki　101Horiguchi, Hiroshi　69

AUTHOR INDEX

112

MMacLeod, Donald IA　10Maemura, Wakiko　73Mankin, Helen　47Mar, Santiago　66Martin, Paul R.　59Matesanz, Beatriz M.　66Matsumiya, Kazumichi　7, 70, 73Matsumoto, Tomohisa　83Maule, John J.　44McKeefry, Declan J.　8Melo, Maria J.　46Mikami, Akichika　32Milburn, Nelda J.　107Milic, Radoje　15Mitsukura, Yasue　110Miyao, Masaru　19Mizokami, Yoko　97, 108Mohd Kamal, Khairidzan　85Mollon, John　2, 61Montagner, Cristina　46Moreira, Humberto　105Morimoto, Takuma　49, 92Murray, Ian J.　8Muto, Yumiko　31, 40, 76

NNagai, Nobuyuki　104Nagai, Takehiro　55, 89, 90Nagasawa, Hikaru　77Nakadomari, Satoshi　69Nakauchi, Shigeki　82, 89, 101Nakayama, Kazuki　90Nardini, Marko　16Nascimento, Sérgio MC　18, 35, 46Negishi, Ippei　74Neitz, Jay　5Neitz, Maureen　5Nesthus, Thomas E.　107

OOda, Koichi　69Oishi, Yuka　77Okajima, Katsunori　14

PPardo, Pedro J.　81Parry, Neil RA　8Patterson, Emily J.　36Perez, Angel Luis　81Pietersen, Alexander N.　59

Horiuchi, Takahiko　84Hoshino, Katsuyoshi　84Hovis, Jeffery K.　107

IIchihara, Yasuyo G.　103Im, Hohjin　50Ishikawa, Tomoharu　106Issolio, Luis　66

JJames , Ian Murray　96João, Catarina AR　18, 35, 46José, Menéndez A.　98Juan, Aparicio A.　98Junod-Ponsard, Nathalie　42

KKale, Alex　9Kalwarowsky, Sarah　16Kanai, Ryota　72Kanazawa, So　75Katagiri, Ryuji　82Kato, Terumi　108Kawamura, Shoji　22Kawashima, Yuki　55, 90Kelber, Almut　6Kellner, Christian J.　63, 94Kelly, Jeremiah 　96Kimura, Eiji　52, 79Knoblauch, Kenneth　58, 80Koida, Kowa　3Komatsu, Hidehiko　48, 68Kremers, Jan　4, 5, 8, 67Krūmiņa, Gunta　86Kubo, Hiroyuki　69Kulikowski, Janus　96Kuriki, Ichiro　40, 73, 75, 89Kusuyama, Takahiro　91Kwan, Benjamin　102

LLanglo, Christopher S.　24, 36Lasan, Mirjam　15Lee, Barry B.　60Lee, Rob J.　53Levanzin, Christina　41Li, Zhaoping　17Lillo, Julio　105Lindsey, Delwin T.　40Linhares, João MM　18, 35, 46Luis, Issolio　98

113

Taniguchi, Shinichiro　108Taylor, Olivia　47Tekavcic Pompe, Manca　15Tekavcic, Bor　15Tokunaga, Rumi　40Tregillus, Katherine EM　99Tsai, Tina　4, 5Tsujimura, Sei-ichi　14

UUchikawa, Keiji　31, 40, 65, 76, 83, 87, 91, 92

Vvan der Zwaag, Weitske　72Vilarigues, Márcia　46Vincent, Joris　9

WWachtler, Thomas　63, 94Wade, Alex R.　72Wang, Wei　43Wassell , Luke　78Webster, Jacquelyn　45Webster, Michael A.　45, 57, 99Weiss, David　38Werner, John S.　25, 26, 57, 99White, Carol　24Widayati, Kanthi A.　32Winkler, Alissa D.　57Wong, Leslie　102

YYaguchi, Hirohisa　97, 108Yamaguchi, Masami K　75Yamauchi, Yasuki　55, 90Yang, Jiale　75Yatsu, Keisuke　55Yoshizawa, Tatsuya　88Yovanovich, Carola AM　6Yura, Hiromi　87

ZZaidi, Qasim　51Zeater, Natalie　59Zele, Andrew J.　67Zheng, Qi　84

RRacey, Chris　72Ripamonti, Caterina　16Rodriguez, Marisa Carmona　20, 34Rogers, Marie R.　80Roth, André　33

SSaito, Atsuko　32Saito, Naohiro　77Sanada, Takahisa M.　68Santiago, Mar　98Santos, Jorge LA　18, 35Sato, Keiko　110Sato, Makito　65Sato, Masayuki　7, 70Sato, Tomoharu　89Sawa, Mitsuru　29Scott, Ryan　47Shelton, Andrew　49Shevell, Steven K.　43Shi, Lin　71Shinomori, Keizo　25, 74Shioiri, Satoshi　7, 40, 70, 73Shishikura, Masami　108Silva, Eva DG　18Skelton, Alice E.　39, 78Smith, Cody　50Smithson, Hannah E.　53Solomon, Samuel G.　59Spillmann, Lothar　57Stenz, Christian　42Stoehr, Brooke　49Strasburger, Hans　60Suero, Maria Isabel　81Summerfelt, Phyllis　24Suryobroto, Bambang　32Suzuki, Kyoko　77

TTakahashi, Aoi　69Takahashi, Yuki　97Takano, Yusuke　79Takayanagi, Yasuyo　21Takeshita, Tomomi　108Takimoto, Hironori　110

NOTES

ICVS 2015 Preliminary timetable (Ver. June 9, 2015)

2015 JULY Saturday 4 Sunday 5 Monday 6 Tuesday 7

08:30 - 09:00

09:00 - 10:00

10:00 - 11:00

11:00 - 12:00

12:00 -13:00

Closing (12:45-13:00)13:00 - 14:00

14:00 - 15:00

15:00 - 16:00

16:00 - 17:00

17:00 - 18:00

18:00 - 19:00

19:00 - 20:00

20:00 - 21:00

Short break

Lunch & Excursion

Reception

Banquet

Invited talk 2Shoji Kawamura

Invited talk 3Hidehiko Komatsu

Coffee break

Poster 1 Poster 2

Verriest lectureJohn S Werner(17:15-18:30)

The "Dress" session

Affected colourvision

Transport time

Colour induction &constancy

Opening (13:30-13:45)

Coffee break

Invited talk 1Kentaro Arikawa

Short break

Friday 3

Registration desk open

Directors'committee

meeting

Registrationdesk open

Coffee break Coffee break Coffee break

Business meeting (11:45-12:45)

Lunch(12:00-13:30)

Lunch(12:00-13:30)

Group photo

Comparative colourvision & physiology

Coffee break

Chromaticmechanisms 1

Director'sLunch

Colour cognition 2Special session in

the memory ofDr. Lanthony

Colour visiondeficiency

Coffee break

Variability in colour vision

Central processing

Chromaticmechanisms 2

Isihara symposium Colour cognition 1

ICVS2015International Colour Vision Society23rd Symposium, Sendai Japan

Documents

July 3-7, 2015 · July 3-7, 2015 Tohoku University, Sendai, Japan. i Published by ICVS2015 Organizing Committee 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan