Configural processing in autism and its relationship to face processing

Neuropsychologia 44 (2006) 110–129

Configural processing in autism and its relationship to face processing

Marlene Behrmanna,∗, Galia Avidana, Grace Lee Leonarda, Rutie Kimchib,Beatriz Lunac, Kate Humphreysa, Nancy Minshewd

a Department of Psychology, Carnegie Mellon University, Pittsburgh, PA 15213-3890, USAb Department of Psychology, University of Haifa, Haifa, Israel

c Departments of Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USAd Departments of Psychiatry and Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA

Received 29 April 2004; received in revised form 31 March 2005; accepted 8 April 2005Available online 23 May 2005

Abstract

Studies of the perceptual performance of individuals with autism have focused, to a large extent, on two domains of visual behavior,one associated with face processing and the other associated with global or holistic processing. Whether autistic individuals differ fromn ins remainsu owed thatt to derivet g task withg d betweenp is not onlyc iminatingb verse impacto©

K

1

“tspmto

“rt

resle

withdo-tive-

alsAb-

ented

pair-pre-viors

0d

eurotypical individuals in these domains is debatable and, moreover, the relationship between the behaviors in these two domanclear. We first compared the face processing ability of 14 adult individuals with autism with that of neurotypical controls and sh

he autistic individuals were slowed in their speed of face discrimination. We then showed that the two groups differed in their abilityhe global whole in two different tasks, one using hierarchical compound letters and the other using a microgenetic primed matchineometric shapes, with the autistic group showing a bias in favor of local information. A significant correlation was also observeerformance on the face task and the configural tasks. We then confirmed the prediction that the ability to derive the global wholeritical for faces but also for other objects as well, as the autistic individuals performed more slowly than the control group in discretween objects. Taken together, the results suggest that the bias for local processing seen in autistic individuals might have an adn their ability to process faces and objects.2005 Elsevier Ltd. All rights reserved.

eywords: Local; Global; Visual processing; Objects; Greebles; Faces; Configural

. Introduction

And this is how I recognize someone if I don’t know whohey are. I see what they are wearing, or if they have a walkingtick, or funny hair, or a certain type of glasses, or they have aarticular way of moving their arms, and I do a Search throughy memories to see if I have met them before.” (Christopher,

he 15-year old autistic protagonist in The Curious Incidentf the Dog in the Night-time by Mark Haddon).

I often get into embarrassing situations because I do notemember faces unless I have seen the people many times orhey have a very distinct facial feature such as a big beard,

∗ Corresponding author. Tel.: +1 412 268 2790; fax: +1 412 268 2798.E-mail address: [email protected] (M. Behrmann).

thick glasses or a strange hairstyle.”(in “Thinking in Pictuand Other Reports from my Life with Autism” by TempGrandin).

Autism is a developmental disorder that is associateda number of characteristic deficits, most notably in themains of social interaction, communication and imaginabehavior (Frith, 2003; Klin, Jones, Schultz, Volkmar, & Cohen, 2002; Volkmar, Lord, Bailey, Schultz, & Klin, 2004). Itis further defined by the finding that most autistic individuexhibit a restricted and repetitive behavioral repertoire.normalities in visual processing have also been documin autism (Kanner, 1943; Society for Autistic Children, 1978),although the nature and extent of the visuoperceptual imment in these individuals remains a topic of debate. Manyvious studies have focused on two visuoperceptual beha

028-3932/$ – see front matter © 2005 Elsevier Ltd. All rights reserved.oi:10.1016/j.neuropsychologia.2005.04.002

M. Behrmann et al. / Neuropsychologia 44 (2006) 110–129 111

in autism, one related to face processing and the other relatedto the derivation of organized wholes from perceptual parts.While both lines of investigation have been fruitful, each setof findings remains somewhat controversial and, moreover,there has only been minimal consideration of the relation-ship between these behaviors in autism. We consider someof the existing data from each domain and then the possi-ble relationship between them before we outline the currentstudies.

Many studies of face processing in children with autismhave demonstrated the presence of an impairment that iswidespread and present from an early age (Dawson et al.,2002), affecting both the perception of and the memory forfaces (Ellis, Ellis, Fraser, & Deb, 1994; Hauck, Fein, Maltby,Waterhouse, & Feinstein, 1998; Klin et al., 1999; Langdell,1977). The perceptual difficulties also affect the perceptionof the affect of faces (Hobson, 1986; Hobson, Ouston, & Lee,1988), the perception of direction of gaze (Jolliffe & Baron-Cohen, 1997) and sometimes even the perception of gender(Hobson, 1987; Njiokiktjien et al., 2001). The same is true foradults with autism, although the impairment is apparently lesssevere in older individuals and in more cognitively able indi-viduals (Boucher & Lewis, 1992). The reported decrement inface processing is consistent with a series of recent functionalimaging studies demonstrating atypical or weak activation ofthe fusiform gyrus, the preeminent area involved in face pro-c ,M ,2 or-g &C th-o sig-n ghth ctiva-t alsoe ,D rel il-i n ina dies.

nt ofg ell-s thata imu-l orw tirev1 taskwU alsor on ofl -

nge-a ssibled

Cohen, 1998; Plaisted, Swettenham, & Rees, 1999), performwell on tasks such as Block Design and Object Assembly thatrequire a local focus (Minshew, Goldstein, & Siegel, 1997)and exhibit superior performance in detecting embedded fig-ures (Happe, 1999; Jolliffe & Baron-Cohen, 1997; Shah &Frith, 1983). One recent study has revealed that autistic chil-dren use gestalt grouping heuristics significantly less oftenthan controls do, resulting in difficulties appreciating inter-element relationships (Brosnan, Scott, Fox, & Pye, 2004).These findings are compatible with the framework, termed‘weak central coherence’ (Frith, 2003; Frith & Happe, 1994),which posits that a fundamental problem in autism is the dif-ficulty in drawing together or integrating individual pieces ofinformation (perceptual or conceptual) to establish meaning,with the resultant reliance on piecemeal, local informationrather than on the overall context. Despite the existing evi-dence, the extent to which autistic subjects truly do show alocal bias or do fail to derive the whole is somewhat contro-versial in itself and this point is specifically addressed in theexperiments below.

Although there are now rich literatures focusing on thenature of face processing and the tendency to focus on localrather than global information in autism, each domain hasmany open questions and, moreover, there is little considera-tion of the relationship between these visual processes. Thisrelationship, however, is of great interest in cognitive neu-r isuals atice pro-c ulusp ualcB& ,2 ingt thea tivev gu-r ownf ing isa singe osia)(K lsoi nts( , &K t,2 cesa anceo ypi-c iono1 cts.T ct ist ssedg rder

essing (Critchley et al., 2000; Grelotti et al., 2005; Pierceuller, Ambroses, Allen, & Courchesne, 2001; Schultz et al.000), despite normal retinotopic and early visual systemanization (Hadjikani et al., 2004; Pierce, Haist, Sedaghat,ourchesne, 2004). The neuroimaging findings are not wiut challenge, however: a very recent study has shownificant fusiform activation in autism, especially in the riemisphere, as would be expected, and with greater a

ion in response to familiar than unfamiliar faces, as isxpected (Hadjikani et al., 2004; Pierce et al., 2004; see alsoalton et al., 2005). The autistic individuals do show a mo

imited cortical network than controls in response to famar faces in this study, but the presence of FFA activatioutism is important and contrasts with most existing stu

The second perceptual domain, concerning the extelobal or holistic processing in autism, has also been wtudied with many, but not all, investigations reportingutistic individuals tend to focus more on the parts of a st

us and to experience difficulty in deriving the global entityhole.1 For example, autistic individuals fail to take the enisual context into account (Happe, 1996; Ropar & Mitchell,999) and fail to perceive impossible geometric figures, ahich requires part integration (Mottron & Belleville, 1993).sing a wide variety of paradigms, investigations have

evealed that autistic individuals show enhanced detectiocal targets in visual search (Plaisted, O’Riordan, & Baron

1 The terms global, holistic and configural are often used interchably in the literature and we do so here too. However, we examine poistinctions between them in the final discussion.

oscience. Faces form a class of perceptually similar vtimuli and are, therefore, thought to be the paradigmxample of a stimulus that relies heavily on configuralessing, with the gestalt or holistic properties of the stimossibly even overriding the contribution of its individomponents (Farah, Wilson, Drain, & Tanaka, 1995; Leder &ruce, 2000; Maurer, Le Grand, & Mondloch, 2002; TanakaFarah, 1993; Tarr & Cheng, 2003; Yovel, Paller, & Levy

005). One might expect then that any difficulty in derivhe global configuration would substantially impairbility to process faces. Indeed, individuals with integraisual agnosia who experience difficulty in deriving confial information, are also impaired both at recognizing knaces and at discriminating novel faces. The reverse findlso reported: individuals who are impaired at face procesither as a result of a brain damage (acquired prosopagnBarton, Press, Keenan, & O’Connor, 2002; Behrmann &imchi, 2003) or as a result of a congenital problem are a

mpaired at extracting configurations from local elemeBehrmann et al., in pressBehrmann, Avidan, Marottaimchi, 2005; Le Grand, Mondloch, Maurer, & Bren004). A further indication of the relationship between fand configurations comes from comparisons of performn upright versus inverted faces, relative to objects. Tally, for normal individuals, recognition and discriminatf faces is better for upright than for inverted faces (Yin,969) and this difference holds to a lesser extent for objehe disproportionate face versus object inversion effe

aken to reflect the fact that upright faces are procelobally or as a whole with extraction of the second-o

112 M. Behrmann et al. / Neuropsychologia 44 (2006) 110–129

relational features—when faces are inverted, the whole orconfiguration is no longer available and a more part-basedsystem is utilized, leading to the observed decrement inperformance (Farah, Tanaka, & Drain, 1996; Maurer et al.,2002; Moscovitch & Moscovitch, 2000). Consistent withthis, prosopagnosic individuals often do not show the faceinversion effect in tasks requiring face discrimination andmay even do better on inverted than upright faces presumablybecause their part-based strategy can proceed unhamperedby attempts at configural processing (Behrmann et al., 2005;Farah et al., 1996; Marotta, McKeeff, & Behrmann, 2002).

If autistic individuals focus unduly on the local features ofthe input, this might adversely impact their face processingand result in a greater dependence on parts than on the wholeof a face. Indeed, some studies have reported that individualswith autism rely more on individual components of the facesuch as the lower face or the mouth than normal individuals(Hobson et al., 1988) and there is a growing consensus thatindividuals with autism process faces in a more analytical,feature-based fashion (Hobson et al., 1988), and attend todifferent features of a face (Joseph & Tanaka, 2003) than dotheir non-autistic counterparts. This bias towards local ele-ments in autism may also interfere with the extraction of thesecond-order statistics, the very process thought to be criticalfor face recognition and discrimination and for the superiorprocessing of upright over inverted faces (Carey & Diamond,1 ota theirc d,& nceb o nots ces-s ,2 ver,2 di-v ttendt ,N e-c dualse ex-a illu-s theyc ,D -a uth inc& ner-a ,2 sed.A con-c ocalp cess-i

tualw ivid-u ly in

recognition memory for other stimuli such as cats, horses andmotorbikes (Blair, Frith, Smith, Abell, & Cipolotti, 2001). Anobvious outstanding question is whether any changes in theirperceptual performance on these other classes of objects mayalso perhaps be explained by the trend towards local process-ing. Although there is consensus that faces are the paradig-matic stimulus requiring configural representation, there isgrowing acknowledgement that other visual stimuli mightalso require configural processing. For example, studies haveshown that, as is true for faces, local shape and surface fea-tures may not be the most efficient strategy for the purposeof discrimination and identification of objects which belongto the same class and are perceptually similar as in the caseof cars, birds, bodies, individual Greebles (seeFig. 6, for ex-ample, of this novel 3D rendered object) (Gauthier & Tarr,1997) or any other class of homogeneous exemplars—to effi-ciently differentiate individual exemplars, additional detailsand ‘configural’ or relational information may be necessary(Gauthier & Tarr, 2002; Maurer et al., 2002; Seitz, 2002; Tarr& Cheng, 2003). If this is so, individuals with autism whofocus on local details might also experience difficulty pro-cessing other non-face stimuli when the need to do individuallevel differentiation arises, although the difficulty might beexaggerated for faces given the nature of the extreme homo-geneity of the exemplars.

In three sets of studies, we address face processing, con-fi wella am-i tistica entsd indi-v ualse eenf ex-p thesei romt tures,t tionsi

2

2

id-u d 53y with2 gen-dm .D.,1 /40,w cs of

n onea

994; Rhodes, 1988). Indeed, individuals with autism are ns affected in behavioral studies by inversion of a face asontrols (Boucher & Lewis, 1992; Davies, Bishop, MansteaTantum, 1994), show even less of a N170 ERP differe

etween upright and inverted faces than controls and dhow temporal or gamma band activity thought to be neary for binding components of upright faces (Grice et al.001; McPartland, Dawson, Webb, Panagiotides, & Car004). All of this is consistent with the idea that autistic iniduals may proceed in a more part-based fashion and ao local aspects of the input (although seeTantam, Monaghanicholson, & Stirling, 1989). Note, however, that some rent studies have challenged the idea that autistic indivixperience difficulty in configural face processing; formple, children with autism are subject to the Thatcherion, just like their control counterparts, suggesting thatan indeed perceive second-order relational features (Rouseonnelly, Hadwin, & Brown, 2004). Also autistic individuls show a processing advantage for recognizing the moontext compared with when it is shown in isolation (JosephTanaka, 2003) and, when cued, are further assisted in geting the whole-face advantage (Lopez, Donnelly, & Hadwin004), suggesting that contextual information is process is evident, there remain many unanswered questionserning configural processing, its relation to possible lreference or bias in autism and its impact on face pro

ng.Although the emphasis of much of the visuopercep

ork in autism has been on the processing of faces, indals with autism have also been shown to perform poor

gural processing and the relationship between them ass object processing more generally. We start off by ex

ning the face processing abilities in a sample of 14 audults. We then present the findings from two experimesigned to examine configural processing in the sameiduals and to explore the extent to which these individxhibit a local bias. We also examine correlations betwace and configural abilities. Finally, in the third set oferiments, we examine the perceptual performance of

ndividuals on other non-face visual objects, all drawn fhe same stimulus class and sharing many perceptual feao evaluate the specificity of any visuoperceptual alteran autism.

. General methodology

.1. Participants

The participants were 14 high-functioning adult indivals with autism (12 male and 2 female), between 19 anears of age, and 27 neurotypical control individuals,control subjects matched as closely as possible by

er, age and education level to each autistic individual.2 Theean full scale IQ score of the autistic group was 104.1 (S7.4). All participants had visual acuity of at least 20ith correction if necessary. Demographic characteristi

2 Because one of the control subjects was well-matched to more thautistic individual, we had 27 rather than 28 control subjects.


Table 1Biographic details and IQ scores of autistic individuals

Autistic (age/gender) Education level VIQ PIQ FSIQ

1 34/F 12 89 78 832 30/M 16 104 116 1103 19/M 13 139 106 1264 47/M 8 90 98 935 41/F 12 80 77 776 46/M 12 88 103 967 42/M 12 94 90 918 24/M 13 116 116 1189 31/M 14 130 113 124

10 53/M 18 118 119 11711 19/M 12 78 81 7812 40/M 15 113 128 12313 35/M 14 106 105 10714 22/M 14 111 112 114

the autistic subjects are provided inTable 1along with IQscores. This study was approved by the Institutional ReviewBoards of the University of Pittsburgh and Carnegie MellonUniversity. Written informed consent was obtained from allparticipants.

Autistic participants had no identifiable etiology such astuberous sclerosis or fragile-X syndrome. Screening teststo determine eligibility of the participants with autism in-cluded the Wechsler Adult Intelligence Scale-III (Wechsler,1997), the Kaufman Test of Educational Achievement (K-TEA)(Kaufman & Kaufman, 1985), the Autism DiagnosticObservation Schedule (ADOS) (Lord et al., 1989) and theAutism Diagnostic Interview (ADI & ADI-Revised; (Le Cou-teur et al., 1989; Lord, Rutter, & Le Couteur, 1994)). The di-agnosis of autism provided by the two structured instrumentswas confirmed by expert clinical opinion (Dr. Minshew). Sub-jects with autism were also required to be in good medicalhealth, free of seizures and have a negative history of trau-matic brain injury. All autistic subjects were cooperative.

Controls were volunteers recruited from the communitywho met preset inclusion and exclusion criteria. Potentialcontrols were screened by completion of a questionnaire ondemographic information and family and personal history.Controls were required to be in good physical health, free ofregular medication usage and have good peer relationships,based on report and staff observations during testing. Con-t tricd

2

wer-b 650( sion1R rdedw ap-p on ab ants

sat in a dimly lit room at a viewing distance of approxi-mately 60 cm from the screen. All experiments were com-pleted in a single session. Reaction time (RT) and accuracywere recorded in all experiments (except for those tasks as-sessing spatial frequency thresholds).

3. Face processing

3.1. Gender and individual level discrimination of faces

This first experiment was designed to examine the faceprocessing abilities of the autistic individuals. Based on pre-vious findings, we expect that the autistic individuals mayperform more poorly than their control counterparts. A fur-ther prediction is that any observed difference will be dispro-portionately exaggerated as the level of categorization be-comes more specific (individual as opposed to gender level)since it is at this level that the need for more fine-grainedperceptual discrimination, and the reliance on second-orderrelations, becomes more critical. This experiment has beenused successfully in the past to show this exact pattern offindings in individuals with prosopagnosia (Behrmann et al.,2005; Gauthier, Behrmann, & Tarr, 1999).

3.1.1. Design and procedureale,

h fromH e,T ame5 air-l tico s ap-p bjectp nt’.T ande2 el ofc (seeF thatw id-u ual( ionsw

thant anda g ab-s sim-p andc hed s thatr be-t eeng rob-l pre-v

rols were excluded if they had a history of neuropsychiaisorder.

.2. General procedure

The experiments were conducted on a Macintosh Poook 540C (9.5 in. monitor) or a Macintosh Quadra15 in. monitor) and were executed with PsyScope ver.2.1 (Cohen, MacWhinney, Flatt, & Provost, 1993) or withSVP 2.5 Software (Tarr, 1994). All responses were recoith two keys marked to identify the stimulus–response ming either on the keyboard or, for the first few subjects,utton box customized to run with PsyScope. Particip

The stimuli consisted of 60 grey-scale faces (half malf female) scanned from a 3D laser and obtainedeinrich Bulthoff and Niko Troje (Max Planck Institutubingen, Germany). All faces were cropped using the s.72× 7.62 cm oval window to remove cues from the h

ine and face contour (seeFig. 1a). There were no diagnosr salient cues on these faces. On each trial, two faceeared side by side on a computer screen until the suressed one of two keys to respond ‘same’ or ‘differehe distance from the middle of each face was 10.67 cmach face subtended a visual angle of 1.8◦ horizontally and.5◦ vertically. Accuracy and RT were measured. The levategorization (perceptual similarity) was manipulatedig. 1a) such that a pair of stimuli could contain facesere (1) identical (20 trials), (2) different gender and indival (GI, 30 trials) and (3) same gender, different individI, 10 trials). The trials were randomized across conditithin a block.Because autistic subjects are almost always slower

heir non-autistic counterparts in producing responsesre more variable in their speed of response, examininolute reaction times may be misleading. Furthermore,ly focusing on interactions, for example, group (autisticontrol)× condition (gender and individual) with RT as tependent measure may be subject to scaling problemesult merely from differences in baseline performanceween the groups rather than from a real interaction betwroup and the conditions of interest. These analytical p

ems are well-recognized and have plagued the literatureiously, for example, in the domain of schizophrenia (Miller,


Fig. 1. Examples of stimuli and results for face experiments. (a) Examplesof stimuli for face discrimination experiment, including one trial where facesdiffer on the basis of gender and one trial where faces differ on the basis ofindividual identity. (b) Mean of median RT (and one SE) for correct differenttrials as a function of conditions of discrimination for autistic and controlgroups.

Chapman, Chapman, & Collins, 1995). In an attempt to becognizant of these potential scaling problems, we not only usethe median (to offset the influence of outliers) for each cellfor each individual but also more importantly, the percentagechange across the experimental conditions is calculated andcompared across groups to control for differences in the ab-solute base RT. We also examined the RTs of each individualand ascertained whether the individual data fall outside of the95% confidence interval of the control subjects, following therecommendations for single case study analysis (Crawford& Garthwaite, 2004) and other statistical recommendations(Cumming & Finch, 2005). Accuracy is also analyzed. Notethat participants are instructed to respond both quickly andaccurately. It is well-known in the neuropsychological liter-ature that, under conditions of unlimited exposure durationsuch as used here (non-data limited), accuracy may not be thebest measure: subjects may simply spend inordinate amountsof time until they are certain that their response is correct andso RT is usually a more telling measure. Additionally, thereare case reports of agnosic individuals, in whom accuracymeasures suggest normal performance, but the corresponding RT data clearly indicate a marked impairment (Delvenne,Seron, Coyette, & Rossion, 2004; Gauthier, Behrmann, et al.,1999; Gerlach, Marstrand, Habekost, & Gade, 2004). It is forthese reasons that the emphasis of the analysis here is on th

RT rather than on accuracy. We recognize that emphasizingaccuracy over speed or vice versa may produce somewhatdifferent results, a point we take up again in the final discus-sion.

3.1.2. Results and discussionThere is neither a group difference nor an interaction

of group× condition in accuracy (F < 1), which is high inboth groups (mean, S.D.: autism 92%, 13.7%; controls 95%,6.9%)—this is not surprising given the unlimited exposureduration of the displays but warrants further discussion andis taken up again later in the paper. The RT analysis per-formed on the median of the correct different trials (for eachcondition) reveals slower RTs for autistic than normal indi-viduals (F(1,39) = 11.21,p < 0.001), as reflected inFig. 1b.There is also a marginally significant interaction with condi-tion (F(1,39) = 4.2,p < 0.07): autistic individuals are slowerat individual versus gender discrimination trials than the con-trol subjects (difference: autism 656 ms, controls 226 ms). At-test based on percent RT increment in the individual over thegender trials (9.7% controls; 14.5% autistic) yields a signifi-cant difference between groups (t(39) = 7.1,p < 0.05), furtherconfirming the increased difficulty for the autistic participantsin the individual level discrimination. As expected, the autis-tic group was slower than controls but perhaps more pertinentis the difference across them when percentage RT incrementi d-u al oft s ise

dif-f cor-r de byt antcF aretp ub-j oupia s iss ncei

facep trols.O ultyf i-n t onc Notet ac-c ponsed pos-s le tor ls ad andt ture

-

e

s considered.Table 2shows the number of autistic indivials whose data fall outside the 95% confidence interv

he control group in the individual level condition and, avident, this is so in 11 out of the 14 participants.

The group difference is not obviously attributable toerences in IQ across the autistic and control groups. Weelated the speed of correct same/different decisions mahe autistic individuals with their IQ scores and no significorrelation was noted with VIQ (p = 0.8), PIQ (p = 0.78) orSIQ (p = 0.54). It is also of interest that when we comp

he RT data from only those autistic subjects (n = 9) whoseerformance IQ is over 100 (the highest functioning s

ects) with their corresponding controls, the autistic grs still significantly slower (F(1,16) = 4.8,p < 0.05) and, inddition, the difference in percent RT across conditiontill evident (390 ms in controls 11.5%; 1035 ms differen autism 16%).

This first experiment suggests a significant slowing inrocessing in the autistic participants, relative to the conf particular relevance is the relatively exaggerated diffic

or the autistic individuals on the individual level discrimation trials, which are thought to rely to a greater extenonfigural processing, compared with the gender trials.hat the group difference is apparent in RT rather than inuracy – because the participants were not under a reseadline so as to mimic a naturalistic situation as best asible, they may have taken longer but eventually were abespond with high accuracy. This first experiment reveaifference in face processing between the autistic group

he controls, and we now explore in greater detail the na


Table 2Tabulation of autistic individuals falling outside of the 95% confidence intervals calculated from the normal control subjects

Autistic (age/gender) Facesa Global localb Configural elementc Objectsd Greeblese

1 34/F − + + + +2 30/M − + inc. + +3 19/M + − − − −4 47/M + + − − −5 41/F + − + + +6 46/M + + + + +7 42/M + + + * −8 24/M + + + + +9 31/M − − + − −10 53/M + + + + n/a11 19/M + + + + n/a12 40/M + + − + +13 35/M + + + + +14 22/M + + + + +

Total 11 11 10/13 10 8/12

‘+’: Falls outside the 95% confidence intervals of the control group; ‘−’: falls within the 95% confidence intervals of the control group;‘*’: falls at the 95%confidence interval of the control group; n/a: did not perform this task; inc.: did not complete task in entirety.

a On trials of two different individual faces of the same gender.b Calculated as{(global inconsistent− global consistent)/(local inconsistent− local consistent)}.c Calculated as (CS–ES) for all prime durations many element trials.d On trials consisting of two different exemplars (e.g., two different chairs).e On trials consisting of two different individual Greebles; only 12 autistic subjects performed this task.

and extent of the configural processing abilities in these sameindividuals.

4. Configural processing in autism

Although the weak central coherence hypothesis suggeststhat autistic individuals may exhibit difficulty in integratinginformation into a coherent or meaningful whole from lo-cal parts (both perceptually and conceptually as in low andhigh level weak central coherence), the empirical findings aremore complicated. While some studies have shown that autis-tic individuals are better able to identify the local than globalletters in compound stimuli and to focus on local elements(sometimes to an even greater degree than is true for the con-trol subjects) in visual search (Plaisted, 2000; Plaisted et al.,1998), this is not always the case. For example Mottron andhis colleagues (Mottron, Burack, Stauder, & Robaey, 1999;Mottron, Burack, Iarocci, Belleville, & Enns, 2003)have re-ported that autistic individuals do not differ from non-autisticsubjects in deriving the identity of the global letter of com-pound stimuli (although perhaps even more surprising is theabsence of the expected global advantage for normal indi-viduals in some of these studies). The presence of a globalbias in autism has also been observed in other studies us-ing somewhat different displays (Ozonoff, Strayer, McMa-h on,& : thefi andt ura-t le anw hefi

which letters are identified at the global or local level and thesecond experiment uses a primed matching paradigm, whichallows for a more fine-grained and temporally extended anal-ysis of configural processing.

4.1. Global/local processing with compound letterstimuli

This experiment adopts the well-known compound stim-uli, which are large hierarchical letters made up of small let-ters, in which the identity of the local letters is either consis-tent or inconsistent with that of the global letter (seeFig. 2a).In the version of the task we used, in separate blocks of tri-als, subjects identify the letter, via key press (‘s’ or ‘h’), ateither the local or the global level. All else being equal, innormal subjects, the global letter is identified faster than thelocal letter, and conflicting information between the globaland the local levels exerts asymmetrical global-to-local in-terference (Navon, 1977). We note that many parameters af-fect these findings including the length of the exposure du-ration (Navon, 1977; Paquet & Merikle, 1984), sparsity oflocal letters (Martin, 1979), foveal placement of the stimulus(Pomerantz, 1983) and spatial certainty (Lamb & Robertson,1988; Navon, 2003). In addition, the blocked version of thetask used here requires focused attention at either the globalor local level rather than divided attention in which, withina thep tistici

4es:

c ers

on, & Filloux, 1994; Rinehart, Bradshaw, Moss, BreretTonge, 2000). Note that there are two separate issues

rst concerns the possible enhanced local bias in autismhe second concerns the ability to derive a global configion. These may be somewhat independent and separabe explore both of them in the following experiments. Trst experiment uses the well-knownNavon (1977)stimuli in

d

block, identification can occur at either level. Whetheraradigm is run blocked or mixed appears to affect au

ndividuals differentially (Plaisted et al., 1999).

.1.1. Design and procedureThe stimuli were four hierarchical letters of two typ

onsistent letters, in which the global and the local lett


Fig. 2. Examples of stimuli and results of global/local task. (a) Four com-pound stimuli, two of which are consistent and share identity at the globaland local level and two of which do not share identity at the global and locallevel. (b) RT (and one SE) for means for control and autism group for globaland local identification as a function of consistency.

shared identity (a large H made of smaller Hs and a large Smade of small Ss) orinconsistent letters, in which the lettersat the two levels had different identities (a large H madeof small Ss and a large S made of small Hs; seeFig. 2a).The global letter subtended 3.2◦ in height and 2.3◦ in width,and the local letter subtended 0.44◦ in height and 0.53◦ inwidth.

The experiment consisted of the factorial combinationof two variables in a repeated measures design: globality(global identification versus local identification), and con-sistency (consistent stimuli versus inconsistent stimuli). Thetwo tasks, local or global identification, were administeredin separate blocks of 96 experimental trials each, precedeby 10 practice trials. The consistent and inconsistent letterswere randomized within block with each letter occurring onan equal number of trials, for a total of 192 trials. Before eachblock, participants were verbally instructed to respond to theglobal or local letters. Each trial was initiated with a centralfixation cross of 500 ms duration. This was immediately re-placed by one of the four possible stimuli, which remainedcentrally on the screen until a response was made. Particpants were instructed to press the left key on the button box(or keyboard) to indicate a response of ‘s’ or the right keyfor ‘h’. The order of the blocks and response designation wascounterbalanced across subjects.

4.1.2. Results and discussionAt the outset, we note that there is neither a group differ-

ence between autistic and control subjects, nor an interactionof any sort, in the accuracy data (allF < 1). Autistic and con-trol subjects were correct on average 98% (S.D., 2%) and98.2% (S.D., 1.3%) of the time, respectively. The high ac-curacy rate is not surprising given the unlimited exposureduration and ease of task (making s/h decisions). The RTdata, calculated on the median for each subject for each con-dition, reveals a significant three-way interaction betweengroup× globality (global and local)× consistency (consis-tent and inconsistent) (F(1,39) = 4.9,p < 0.05). There are alsomain effects of group and of globality (p < 0.0001). As is evi-dent fromFig. 2b, under these testing conditions, the controlsubjects responded quickly and showed a slight advantagefor global over local identification (23 ms) and a slight asym-metry with greater slowing in the inconsistent case (relativeto the congruent case) when local identification is required(interference from globally incongruous letter) than whenglobal identification is required (interference from locallyincongruous letters). This global advantage and the global-to-local interference replicates the standard findings (Navon,2003), although the condition differences may not be as largeas usual given the unlimited duration and repeated foveal pre-sentation.

b-r-

hnoalntnen-ali-o-calmayh,antis-insest-n

n-ndndri-ashel-e

d

i-

The autistic subjects were slower than the control sujects overall, but most importantly, a different pattern of peformance is observed for them (Fig. 2b). The autistic groupis overall faster for local than global identification althougthis difference comes from the inconsistent trials: there isstatistically significant difference between global and locidentification in the consistent case, but in the inconsistecase, local identification is faster than global identificatio(p < 0.05). The latter result, namely greater slowing in thinconsistent case when global identification is required, idicates a large local-to-global interference. The faster locidentification and the local-to-global interference both indcate that autistic individuals show a local bias in their prcessing. It is the case, however, that there is no obvious loadvantage in the consistent case suggesting that therebe some partial processing of the global identity too whicwhen congruent with the local letter, can be extracted. We cinfer then that, under the conditions employed here, the autic individuals were able to derive the global configurationthe consistent condition, but that their local bias gave rito large interference in the inconsistent condition, suggeing that it was difficult to attain a stable global configuratiowhen the elements had a conflicting identity.

Given the ongoing controversy in the autism literature cocerning the extent to which processing is locally biased athe extent to which configural processing is possible, agiven the suggestion that the autistic group in this expement may be able to derive the global identity as wellthe local identity in the consistent case, we examined tdata of each autistic subject individually. To this end, we caculated the number of autistic individuals who fall outsid


the 95% confidence intervals of the control group, calculatedas{(global inconsistent− global consistent)/(local inconsis-tent− local consistent)} and 11 of the autistic subjects falloutside the intervals. We also conducted pairwise ANOVAswith each autistic subject and his/her two matched controls asthe between-subjects variable and globality and consistencyas the within-subjects variables. Nine of the 14 pairwise com-parisons show the significant interaction with group, suggest-ing that the pattern we observe for the group is present in themajority of autistic subjects but not in all of them as in theconfidence interval analysis.

A number of possible explanations for the observed vari-ance within the autistic group may exist. One immediate pos-sibility is that autistic individuals really do differ in the extentto which they can undertake configural processing. Anotherpossibility is that ‘weak coherence’ is a cognitive style ratherthan a deficit per se and the extent to which configural pro-cessing manifests is a function of the autistic individual abil-ity to avoid/adopt this style when instructed to do so (Booth,Charlton, Hughes, & Happe, 2003). An alternative explana-tion has to do with the parameters of this experiment: becausethe stimuli are presented for unlimited exposure duration,with enough time, many autistic subjects may be able to de-rive the global shape. It is also the case that the presence ofmultiple local elements may assist this process; a display thatis relatively sparse with few local elements biases away fromg ents(& s,w sub-j ciallyw theyc tionsr

4o

cand onsa mentp ts ing r ofl ed af malle g butt2 fewl d thet d thep to ast orale e ofp istici t dos also

interact with the number of elements such that with sufficienttime only the many- but not the few-element condition maylend itself more easily to configural processing in autism (asin the previous experiment).

This experiment used the primed matching paradigm(Beller, 1971): participants view a prime followed imme-diately by a pair of test figures, and judge, as rapidly andaccurately as possible, whether the two test figures are thesame or different (seeFig. 3a). No response is made to theprime itself. Primes and probes are made of few or of manyelements (but in a single trial, prime and probe always sharethe same number of elements). There were two types of testpairs defined by their similarity to the prime (seeFig. 3a):the element-similarity (ES) test pairs in which the test fig-ures were similar to the prime in their local elements but dif-fered in global configuration, and theconfiguration-similarity(CS) test pairs in which the figures were similar to the primein global configuration but differed in local elements. Thespeed ofsame responses to the test figures depends on therepresentational similarity between the prime and the testfigures: responses are faster when the test figures are similarto the prime than when they are dissimilar to it. For exam-ple, it is now well-known that, in neurotypical individuals(Behrmann & Kimchi, 2003; Kimchi, 1998), the availabilityof elements and configuration depends on the number andrelative size of the elements. For few, relatively large ele-m pro-c theyc ny-e ction:t evena restr , thee g du-r ts area imei rnalr2 erei e ofe als,a

4ress-

i werer inanth enta ondsm ondm entp cir-c pat-t airs,e . Theg

lobal shape whereas the presence of multiple local elemas in this case) assists in the extraction of the whole (Bacon

Egeth, 1991; Kimchi, 1998). Thus, in these conditionith enough time and enough local elements, autistic

ects may be able to assemble the global shape (espeith help from the consistent local elements). Whetheran still derive the global shape under more taxing condiemains to be determined.

.2. Microgenetic analysis of the perceptualrganization of hierarchical stimuli

Given the uncertainty about whether autistic subjectserive global identity under more challenging conditind the apparent within-group variance, this next experirobes the configural processing of the autistic subjecreater detail. In this experiment, we varied the numbe

ocal elements across two displays, one of which containew large elements and one of which contained many slements. The former is thought to bias local processin

he latter is thought to bias global processing (Kimchi, 1998,000). Importantly, as well as using displays that have

arge or many small elements, a prime is presented anemporal interval between the appearance of the prime anrobe display is manipulated. This approach, referred

he microgenetic approach, involves examining the tempvolution of the percept, rather than just the final outcomerception. One prediction is that, with enough time, aut

ndividuals are able to derive the global whole but cannoo under brief exposure durations. The time course may

ents, the component elements are available early on inessing (ES advantage) and, only, with more time, areonfigured or grouped into a global configuration. For malement patterns, there is an interesting U-shaped fun

he configuration is available very early (CS advantage),t 40 ms, suggesting that normal individuals derive the foapidly before the trees. At the intermediate durationslements themselves are individuated and finally, at lonations (690 ms), both the configuration and the elemenvailable to the observer. By varying the timing of the pr

n relation to the probe, we can tap earlier and later inteepresentations (Behrmann & Kimchi, 2003; Kimchi, 1998,000; Sekuler & Palmer, 1992). The question addressed h

s whether the same effects of number and relative sizlements influence the perception of the autistic individus normal individuals, and if so, how early in time.

.2.1. Design and procedureResponses to the visual displays were made by p

ng one of two response keys, and RTs and accuracyecorded by the computer. Participants used their domand for responding. The priming stimuli were few-elemnd many-element hierarchical patterns (global diamade up of circles). The few-element prime was a diamade of four relatively large circles, and the many-elemrime was a diamond made of sixteen relatively smallles. Each test stimulus consisted of two hierarchicalerns. There were two types of test pairs, ES and CS pach of which gave rise to same and different responseslobal diamond subtended 1.25◦, and the global square 0.96◦.


Fig. 3. Examples of stimuli and results of few/many microgenetic experiment. (a) Primed match paradigm: probes, consisting of few and many elements,arefollowed, after varying SOAs, by test pairs which require ‘same’ or ‘different’ responses and which are similar to the prime in elements or configuration. (b)Group means of RT (and one SE) for (i) controls and (ii) autistic individuals for few and many displays, shown for configuration similarity (CS) and elementsimilarity (ES) trials as a function of SOA.


Each individual circle element subtended 0.36◦ (in diameter)in the few-element patterns, and 0.18◦ in the many-elementpatterns. Each individual square element subtended 0.38◦ inthe few patterns, and 0.19◦ in the many-element patterns. Thedistance between the centers of the two stimuli in a test pairwas 0.7 cm.

The experiment consisted of the factorial combinationof four factors: prime type (few-element or many-element);prime duration (40, 90, 190, 390 or 690 ms); test type (ESand CS); and response choice (“same” or “different”). Thefew-element and many-element primes were administeredin separate blocks of 160 trials each. All the combinationsof the three factors (prime duration, test type and response)were randomized within block with each combination oc-curring on an equal number of trials. Each trial consistedof the following: first, a small fixation dot appeared in thecenter of the screen for 250 ms, followed by a prime. Thepresentation time for the priming stimulus was equally andrandomly distributed among 40, 90, 190, 390 and 690 ms. Im-mediately after the presentation of the prime, the test displayappeared and remained until the response, for a maximum of3000 ms. The test display contained two figures presented oneither side of the location previously occupied by the prime.Participants had to decide whether the two figures were thesame or different and respond accurately and quickly usingthe response keys. Each individual completed 320 trials. Six-t enta s. Wenc werei

4.D.:

a gainn reenf eent of theot ts fpe ls ia da onlyf thes andt e ofc entsb im-p og thef tagef r them gestS t the

mid-durations is an ES advantage apparent. These data repli-cate the previous findings using this paradigm (Behrmann& Kimchi, 2003; Kimchi, 1998), and other previous resultsshowing global representation with many-element stimuli un-der short exposures (Navon, 1977; Paquet & Merikle, 1984).Of particular pertinence for the comparison with the autisticgroup, we point out the advantage for greater priming of thelocal elements for few-element displays and the rapid abilityto derive a global configuration of many items at early SOAs.

For the autistic group, there is also a large advantage forthe ES over CS test pairs for few-element trials (88 ms), sug-gesting a slightly greater local bias for the autistic subjectswith few, large elements than for the controls (note the un-explained anomalous drop in CS for autistic group at 90 mswhich is also diminishing the full extent of the local advan-tage or ES). Of relevance too, is the absence of priming of theconfigural representation for the autistic group at any primeduration whereas CS = ES for the controls at both short andlong durations for many elements; in contrast, there is a sub-stantial advantage (68 ms) for ES over CS for many-elementdisplays across all exposure durations. The major finding,then, is that there is no evidence of benefit from the prime forthe CS condition in autism for many-element items as there isin normal control individuals. Instead, a robust and persistentbenefit (except for 90 ms few elements) for the ES test pairsis obtained for few-element and many-element displays.

iffer-e s andaa on oftad n-d nceb ele-m tismg d fort ing,g sing.H d) atw stici ly at , ares omT thee s onm

ati-b ent( seee busta l-to-l r ESi ex-p ess tog

een practice trials were completed for each of few-elemnd many-element patterns before the experimental trialote that one autistic individual (subject 2Table 1) and hisontrols were not included in this analysis as his datancomplete.

.2.2. Results and discussionAccuracy rates were high for both groups (mean and S

utism 98.3%, S.D. 3.1%; controls 98.1%, S.D. 4.3%), aot surprising given that the test pair remains on the sc

or unlimited duration. There were no differences betwhe groups nor any interactions between group and anyther variables on accuracy (F < 1). In light of this, we turn to

he RT data. Mean of median correctsame RTs for prime-tesimilarity (ES and CS) are plotted inFig. 3b as a function orime duration for each prime type (few-element andmany-lement patterns) for the control and autistic groups (panend ii, respectively). Note that onlysame trials are analyzes the relationship between the probe and test pair is

ully controlled when the two items in the test pair areame (for example, prime is diamond made of circlesest pair is made of two squares, both of which are madircles so, in both halves of the test pair, the local elemut not global configuration are shared with prime). Mostortantly, as shown inFig. 3b, the patterns of data for the twroups are statistically different. For the control group, for

ew-element display (i, left panel), there is a 72 ms advanor ES over CS, collapsed across duration. In contrast, foany-element display, very early on, as well as at the lonOA, there are equally rapid RTs for ES and CS. Only a

The statistical analyses support these findings: the dnce between CS and ES is significant across the groups a function of few/many elements (F(1,36) = 4.6,p < 0.05),s described above. There is also a significant interacti

est type× group× prime duration (F(4,144) = 2.7,p < 0.05)nd a marginally significant interaction of prime type× primeuration× group (F(4,144) = 1.9,p = 0.09). Post hoc tests iicate that, at 40 ms SOA, there is no pairwise differeetween CS and ES for the control group for the manyent display whereas this difference persists for the auroup. One important point is that 40 ms may be too rapi

he autistic subjects to show the early configuration primiven that there is a reduction in their speed of procesowever, there is no time point (in the range we testehich the configuration priming is observed for the auti

ndividuals suggesting that they are not exhibiting mereemporal delay or offset relative to the controls but, ratherhowing a different pattern of behavior. As is evident frable 2, 10 of the 13 autistic individuals who completedxperiment fall outside the normal confidence intervalany element items (calculating all CS− ES).The findings from this experiment are roughly comp

le with those from the global/local hierarchical experimSection4.1). In both cases, for the control subjects, wevidence of global or configural processing: a small but rodvantage for global over local identification and globa

ocal interference, and an equivalence in RT for CS oven many-element trials in this experiment at early and lateosure durations. The autistic subjects show some acclobal identity in the global/local experiment (Section4.1),


possibly afforded by the identity and numerosity of the lo-cal elements. In this current experiment, there is no apparentevidence for global processing and the enhancement of lo-cal processing is striking, as evident in the persistent andlarge difference between CS and ES in both the few and themany-element trials. To the extent that adults with autismhave the capacity to derive a global whole, this ability israther weak and possibly supported by the opportunity forlocal elements to prime the global shape in the global/localexperiment. Note that the patterns used here are all inconsis-tent (squares made of circles or diamonds made of squares)so there is no such opportunity for local facilitation. The find-ings from this experiment are consistent with the recent datashowing that autistic individuals fail to process inter-elementrelationships and show a bias away from gestalt groupingprinciples (Brosnan et al., 2004).

4.3. Spatial frequency thresholds

Before claiming that the reduced pattern of a global ad-vantage in autism is one of impaired configural processing,we need to rule out some alternative explanations. One suchexplanation concerns possible differences in low-level spatialfrequency analyses. Several researchers have suggested an in-volvement of spatial filters, based on spatial frequency chan-nels, operating at early visual processing (Ginsburg, 1986) int e, nol undw hicalsH1 ,& ef-f hus,o uceda lusm lows ectt ro-c lows ects.T tistics com-p

4tab-

l 0.3,1 tionw etedfi aysc at 1a np magea fur-t s and

Fig. 4. Examples of stimuli for testing low-level vision. Examples of stimuliused to establish contrast thresholds across different spatial frequencies.Examples here are 1 cycle per inch (left) and 30 cycles per inch (right). In asequential paired task, subjects indicate whether the first or second stimulusin the pair contains the grating.

it, in turn, was replaced by a 200 ms blank screen. At thispoint, the subject was required to decide whether the first orsecond image contained the grating. Feedback was providedto the subject after each trial. A series of five practice trialswas presented before the first block and, for most subjects,the order of blocks was counterbalanced. If the response wascorrect, a more difficult discrimination (decreased contrastby 0.2) was presented on the next trial. If the response wasincorrect, the contrast was increased by 0.2. A log contrastthreshold was determined for each cpi using method of lim-its where threshold is defined as the value of contrast thatproduces 82% accuracy. Note that one autistic subject wasunwilling to complete this experiment and two of them com-pleted all cpis except for 0.3 (as they completed 0.1 instead inerror).

4.3.2. Results and discussionThe mean log contrast thresholds obtained for the autistic

patients was compared with the mean of the normal subjects.A group× spatial frequency analysis reveals no differenceacross groups, nor an interaction of group× frequency (bothF < 1). This finding confirms that the autistic individuals per-form within the normal boundaries in detecting low and highfrequency gratings. Having ruled out the possibility that thediscrepancy between the patients and the normal control sub-jects in their perception of the hierarchical stimuli is due tod or-m re-fl eri-m ssingo

5

jects,w lobalp thant ultyo

he perception of global and local structures. For examplatency advantage for global over local processing is fohen low-spatial frequencies are removed from hierarctimuli (Badcock, Whitworth, Badcock, & Lovegrove, 1990;ughes, Fendrich, & Reuter-Lorenz, 1990; Lamb & Yund,993; Shulman & Wilson, 1987; Shulman, Sullivan, GishSakoda, 1986), suggesting that the global advantage

ect is mediated by low spatial frequency channels. Tne possible explanation for the autistic subjects’ redbility to perceive the global form of a hierarchical stimuight concern a fundamental limitation in processing

patial frequency information. If so, then we might exphat autistic individuals should be relatively impaired at pessing low frequency displays, resulting in an increasedpatial frequency threshold, relative to their control subjo evaluate this, we established thresholds for the auubjects across a wide range of spatial frequencies andared them to those of control participants.

.3.1. Design and procedureTo document the spatial frequency function, we es

ished, for each individual, the log contrast thresholds at, 3, 10 and 30 cycles per inch (cpi) using a Matlab funchich implements a discrimination task. Subjects complve blocks of trials, with 20 trials each and using displorresponding to one of the cpis (examples of stimulind 30 cpis are shown inFig. 4). In each trial, a fixatiooint appeared on the screen for 1 s. After 200 ms, one ippeared for 200 ms followed by a blank screen for a

her 200 ms. A second image then appeared for 200 m

ifferential limitations in analyzing spatial frequency infation, it seems that the failure to derive a global whole

ects a difficulty in configural processing. In the final expents, then, we examine the impact of configural procen other visual, non-face stimuli.

. Discrimination of non-face objects

The prediction to be tested here is that the autistic subho show a bias for local processing and less efficient grocessing than the controls, may also perform less well

he controls on non-face objects especially as the difficf perceptual discrimination increases.


5.1. Object processing

5.1.1. Design and procedureA set of 80 grey-scale objects was created by rendering

3D object models using Silicon Graphics Inventor Software.The object models were obtained from multiple sources, in-cluding public domain sites and commercial CD-ROMS. Aswas the case for the face testing, on each trial, two stimuli(of varying levels of similarity) were placed side by side on acomputer screen for an unlimited duration (seeFig. 5a) untilthe subject pressed a same or different key. Accuracy and RTwere measured. The level of categorization was implementedas follows: pairs of stimuli for each of four conditions werecreated in the following way: (1) identical (40 trials, 2 rep-etitions), (2) pair where stimuli differ at basic, subordinateand exemplar levels (BSE, 20 trials: car and a duck), (3) pairwhere stimuli differ at subordinate and exemplar levels (SE,20 trials): duck and a pelican) and (4) pair where stimuliare different exemplars but from the same subordinate level(E, 20 trials: 2 different ducks). The trials were randomizedacross conditions within a block.

5.1.2. Results and discussionThe analysis of the median RT on correct different trials

reveals a significant interaction between group and condi-t bits cific,t n fort irea basic

F tione tiont mplarl as af

(6.9% increment) judgment and a further 206 ms (10%) tomake the exemplar decision, and the corresponding numbersfor the control group are 62 ms (4.3%) and 122 ms (7.5%).Note that, although a significant group× condition interac-tion is present, the speed of the base reaction time and themagnitudes of the cross-condition difference are lower thanin the face discrimination experiment (compare withFig. 1and notey-axis differences). The analysis of the percent RTdifference scores using at-test shows a group difference inRT between basic and subordinate (p < 0.05) although thisdoes not reach statistical significance between subordinateand exemplar (p > .05). Note that the between group differ-ences do hold when a subanalysis of RT is done comparingthe nine highest IQ (performance IQ > 100) autistic individu-als and their controls counterparts (p = 0.043). Also, as shownin Table 2, 10 (and 1 on boundary) autistic participants felloutside the 95% confidence intervals of the control subjectsbased on RTs on the exemplar trials of the task. There wasneither a group nor a group× condition interaction in the ac-curacy data (F < 1) (mean S.D.: autistic 98%, 3.9%; controls97%, 4%), presumably because the exposure duration wasunlimited and the effects manifested in speed rather than inaccuracy.

5.2. Greeble processing

5bles

( jectt e on

F peri-m fer att eansfor control and autism group as a function of condition of discrimination.

ion (F(2,78) = 5.1,p < 0.008); although both groups exhilower RTs as level of categorization becomes more spehis is so to a somewhat greater degree for the autistic thahe control group (seeFig. 5b). Thus, autistic subjects requn additional 149 ms to make the subordinate over the

ig. 5. Examples of stimuli and results of common object discriminaxperiment. (a) Examples of stimuli from common object discriminaask, showing pairs of stimuli that differ at the basic, subordinate or exeevels. (b) RT (and one SE) for means for control and autism groupunction of condition of discrimination.

.2.1. Design and procedureThe stimuli consisted of 60 grey-scale pictures of Gree

examples inFig. 6a). As was the case for the face and obesting, on each trial, two stimuli were placed side by sid

ig. 6. Examples of stimuli and results of Greeble discrimination exent. (a) Examples of stimuli from Greeble task, showing pairs that dif

he basic, family, gender and individual level. (b) RT (and one SE) for m


a computer screen for an unlimited duration until the subjectpressed a same or different key. Accuracy and RT were mea-sured. Greebles are a class of novel stimuli, designed to mimicthe processing demands of faces, i.e., all have the same num-ber and rough geometry of local parts requiring the derivationof spatial relationships between them. Additionally, to paral-lel the level of categorization of faces (face versus object, twofaces of different gender or individual faces of the same gen-der), the Greebles are designed to fall into families which allshare the same main body. Within each family, there are twopossible genders (appendages go up or down) and then withinthe family and gender, there are individual, unique Greebles.In this task, the level of categorization was implemented inthe following way: there were five conditions (1) identical (63trials), (2) basic (paired with a familiar object, such as a car),(3) different gender (G; paired with a Greeble from anothergender but same family), (4) different family (F; paired with aGreeble of different family but same gender) and (5) individ-ual (I, paired with a Greeble with different individual identitybut from same family and gender). Conditions 2–5 had 30 tri-als each. Only 12 autistic subjects and corresponding controlsubjects completed this experiment (the remaining two inad-vertently completed a more complex version which includedupright and inverted Greebles—we note, however, that thefindings from these two subjects are roughly the same as forthose tested here).

5dif-

f( -t dif-fi er,i dif-f r thea eenb 9 ms( fam-i forc in-d 2%)f cantg tn a in-c hert d theot n-d en inT skf e in-d r ani .:a

ares with

their control counterparts but that the nature of the decisionis not equal across all conditions. For example, autistic in-dividuals, like the controls, do not show much of a RT dif-ference between decisions involving family (main body) anddecisions involving gender (appendage direction). The autis-tic individuals, however, as a group, are slowed in differen-tiating between two Greebles compared with differentiatingbetween a Greeble and another object (basic level) even whenabsolute reaction time is taken into account. Although we ex-pected that the autistic individuals would also be dispropor-tionately impaired in discriminating between two individualGreebles, the autistic subjects are only minimally slower thanthe controls when a difference score is computed and baselineRT taken into account.

6. Relationship between configural and face andobject processing

The findings thus far indicate that the group of autisticindividuals was slower at face processing than their con-trols, especially as the level of categorization and perceptualsimilarity became more fine-grained. The autistic group alsoshowed a greater local bias than the control group and, underthe testing conditions employed, did not show the configu-ral or global processing observed in the control pattern. Theautistic individuals also performed more slowly than the con-t thist r morep wasr

inet nfig-u t be-t andt thec e in-d vals( 3( r ofs crosst thec bjectf

con-d ove,yc T inf indi-v alsoo d them roup[ r-r0

s arei g is

.2.2. Results and discussionAn analysis of the median RT data from correct

erent trials reveals an interaction of group× conditionF(3,90) = 6.3,p < 0.001). As is evident fromFig. 6b, the conrol subjects show a graded effect with RT increasing withculty of perceptual discrimination. This slowing, howevs disproportionately increased in the autism group. Theerence between some conditions is almost double foutistic than for the control groups; the difference betwasic and gender is 579 ms (22%) for autistic and 3117%) for controls, the difference between gender andly trials is 188 ms (5.4%) for autistic and 113 ms (4.9%)ontrols and, finally, the difference between family andividuals is 631 ms (14.8%) for autistic and 382 ms (13.

or controls. The percent difference score reveals a signifiroup difference in going from basic to gender (p < 0.05) buot between the other conditions. An analysis of the datluding the highest IQ autistic individuals (only eight rathan nine as one of the high IQ autistic subjects performether version of the task) does reveal a group× condition in-

eraction (p < 0.038) and, with the exception of family to geer, all cross-condition differences are significant. As seable 2, 8 of 12 autistic individuals who completed this taell outside the 95% confidence intervals on the Greeblividual task. There was neither a main effect of group no

nteraction evident in the accuracy data (F < 1) (mean S.Dutistics 92%, 13.5%; controls 94.6%, 4.5%).

These findings suggest that individuals with autismlower in making decisions about Greebles compared

rol group on non-face common and novel objects, andoo was true to a somewhat greater degree as the need forecise discrimination (based on configural knowledge)equired.

Given that one of the goals of this study was to examhe relationship between face/object processing and coral processing, we performed correlation analyses firs

ween the two configural tasks and then between themhe face/object tasks. We took the individual values fromonfigural tasks, which we used to establish whether thividual subjects fell outside the normal confidence interseeTable 2) and correlated them. Ther2 value was 0.2p = 0.09), which is encouraging given the small numbeubjects and suggests some replicability of the findings ahe two configural tasks. We then went on to investigateorrelation with faces/objects using the value for each surom the global/local task.

The median RT for face processing, collapsed acrossition, correlated with the configural value described abielded a significantr2 value of 0.61 (p = 0.03). Althoughorrelation is not causation, the relationship between Race processing and a local bias is clear in the autisticiduals. Of interest also is that a significant correlation isbserved between the effect of globality, as above, anedian RT on the Greeble experiment in the autistic g

r2 value of 0.47 (p = 0.01; 12 individuals)]. This same coelation does not reach significance for objects [r2 value of.21,p = 0.1].

Taken together, the results of the correlation analysenformative: the slowing in face (and Greeble) processin


well correlated with the relative superiority of processing lo-cal information. The lack of a significant correlation with ob-jects is consistent with the idea that the objects may well relyon configural processing (especially at an individual level)but to a lesser extent and indeed, the relationship betweenglobal and object processing is much weaker.

Before turning to the final discussion, we examine theprofile of the individual autistic subjects across the five ex-periments using the data fromTable 2which shows whetheron each task, the subjects performance fell beyond the normal95% confidence interval. Four of the 14 subjects fall outsidethe normal confidence intervals on all five experiments and anadditional two who did not complete the Greebles task, didso on the remaining four experiments (and, as mentioned,showed the same findings as we see here on the Greeble taskthey did perform). A further three subjects fall below the low-est confidence intervals of the normal limits on four of thefive tasks. Two subjects did so on a single task and one subjectdid so on two tasks (faces and global/local).

Taken together, these explorations of the patterns of indi-vidual data provide reasonably, although not perfectly, goodsupport for the relationship between the configural and facetask and to a somewhat lesser degree between configural andobject and Greebles task. It is also the case that many, al-though not all, autistic individuals exhibit the same patternof performance in RT.

7

ng ina lineo ormp ntityr irec-t dl nt tow t orm suali howa thanc d,2e calc lear.T s ofi m. Afi fromt peci-fi

7r

e un-d e sig-

nificantly slowed at making same/different discriminationsbetween novel faces, relative to their matched control coun-terparts, and this was so to a greater extent as the perceptualdiscrimination was more fine-grained. The second set of stud-ies explored the configural processing abilities of the sameautistic subjects. Relative to the controls, the autistic individu-als show a local bias or local superiority such that identifyinglocal elements was faster than identifying global letters orshapes and identifying a compound letter at the global levelwas slowed by inconsistent local information.

A more detailed investigation, manipulating the numberof elements in a display and the time course by which thelocal versus global information is available, revealed a pat-tern of behavior that differs from the well-established profileof neurotypical individuals. In particular, the autistic individ-uals did not show the signature effects of normal groupingbehavior in displays with many items: early priming for testpairs that are configurally similar to the prime (CS) over itemsthat are similar to the prime in the local elements (ES) reflect-ing the global advantage with many elements (Kimchi, 1998)at brief exposure durations (Navon, 1977; Paquet & Merikle,1984). Instead, the autistic individuals are primed by the localelements and show a clear advantage for the elements overthe whole shape. Taken together, the large local-to-global in-terference in the global/local experiment, and the absenceof facilitation from the global configuration in the primedm anyo uralo ble tod ion,o for-m locale

ancei e ins t thed tog ntsi ingi isualp aved ptualp s int ab rn ina thei

l dif-f e ob-j tlys rim-i truef ossa asa e ont bject

. General discussion

To date, much research in visuoperceptual processiutism has focused on two lines of investigation. The onef investigation has shown that autistic individuals perfoorly on tasks requiring face processing, including ideecognition as well as discrimination of gender, gaze dion and emotion (Teunisse & De Gelder, 2003). The seconine of investigation has been concerned with the extehich autistic individuals are able to derive a cohereneaningful whole from the local elements present in vi

nput. While most studies report that autistic individuals slocal bias, sometimes leading to superior performanceontrol subjects (Caron, Mottron, Rainville, & Chouinar004; Plaisted, Saksida, Alcantara, & Weisblatt, 2003), thextent to which autistic individuals can integrate the loomponents and derive the global configuration is less che focus of the current paper is on each of these line

nvestigation as well as on the relationship between thenal issue addressed is whether autistic subjects differheir controls on non-face stimuli, so as to ascertain the scity of any altered perceptual patterns in autism.

.1. Face/object processing in autism and theelationship to configural processing

In the course of this paper, three series of studies werertaken. The first set revealed that 14 autistic adults wer

atching experiment (in the many-element condition) atf the possible prime durations (not just an early configrganization) suggest that the autistic subjects may be aerive a global configuration, in a time-consuming fashnly under favorable circumstances (facilitating local ination) and that, in general, they show a bias towardslements.

We also confirmed that the poorer perceptual performn autism is not attributable to a fundamental differencpatial frequency thresholds. Of particular interest is thaifficulty in configural processing, indexed by the failureroup rapidly and efficiently many relatively small eleme

nto a global shape, was positively correlated with the slown face processing. Although our focus has been on vrocessing, we note the visual perceptual difficulty we hocumented here may be part of a more general perceattern; the apparent difficulty in detecting configuration

he auditory modality (Foxton et al., 2003) also suggestsias towards local processing and may reflect a patteutism that is independent of the sensory modality of

nput.The third set of studies showed that the perceptua

erences in autism extended beyond faces to non-facects too, with the autistic individuals being significanlowed, relative to the controls, on same/different discnation tasks. This slowing was not as great as wasor faces and it did not hold perfectly consistently acrll individuals and all conditions. A positive correlation wlso noted between the local bias and the performanc

he Greeble processing task but not on the non-face o


task. Taken together, these findings indicate important differ-ences in visuoperceptual processing in autism compared withthe control subjects in both face/non-object and in configuralprocessing and further suggest that there may be a positiverelationship between these patterns of performance.

7.2. Preference for local information in autism

The obvious question is what underlying mechanism givesrise to these differences in perceptual performance. We haveshown that there are no differences in spatial frequencythresholds in autism and in the control group, suggesting thatthe differences are probably not arising at the very early stagesof the visual system. Consistent with this, a recent functionalmagnetic resonance imaging study found no differences be-tween the sensory visual areas of people with autism andnormal controls (Hadjikani et al., 2004)—the ratio of centralto peripheral visual field representation was normal and themaps of retinotopic organization did not differ from those ofcontrols in any respect. This result would suggest that the vi-sual abnormalities arise further upstream and that the processinvolved in the perceptual organization and grouping of thelocal elements may be the source of the difference. However,we should note that several studies have argued for a low-levelvisual deficit in autism in the domain of motion perception;given random dot stereograms with the requirement to detectc esh-od -t hrt mag-np nte-g haved tternso iplep entsw rosst t asw entsa alsoa oms ac

bjectp ay bee vid-u ocal

agues( alm malll ear-i r,& velg

elements and face processing is well-established in other pop-ulations. There are several studies showing that individualswith prosopagnosia perform poorly on tasks that require theintegration of perceptual information (Barton et al., 2002)and integrative agnosic patients who are impaired at group-ing information to form a global shape may show concurrentproblems in object and face recognition (Behrmann & Kim-chi, 2003; Ricci, Vaishnavi, & Chatterjee, 1999). Moreover,individuals who are congenitally prosopagnosic (CP), with noidentifiable neural substrate that gives rise to this behavioralalteration, are impaired on the global/local task and show aprofile similar to that of the autistic individuals on the verysame few/many experiment conducted here (Behrmann et al.,2005). We note that these CP individuals also differ from theircontrols on the non-face objects, as is the case for the autis-tic individuals tested here. The CP individuals, however, donot share the neuropsychological and social deficits presentin most autistic individuals. These sources of evidence fromother populations bolster the claim that there is a relation-ship between face and configural processing. But, of course,correlation is not causation and causality still remains to bedetermined.

In sum, the view that we have taken here is that the slowingin face processing in autism might arise from a more funda-mental visual (and possibly even sensory independent) biastowards the local elements and perhaps simultaneous or resul-t lusi ofp isualp andsf thec at ane o thei ob-j o thes

nceo eent stud-i tisma ptual,d smh2 ,2 er-c andt itiono itht thef tiono mit-t i, &G 3t ar-e hy-p ility

oherent motion, individuals with autism have higher thrlds for detection than their peers (Milne et al., 2002), areeficient in motion direction discrimination (Bertone, Mot

ron, Jelenic, & Faubert, 2003) and experience difficulty witapidly moving stimuli (Gepner & Mestre, 2002). Althoughhese biases have been attributed to an alteration in theocellular pathways in autism (Milne et al., 2002), they mayossibly be reinterpreted as a higher-order difficulty in irating elements, reflecting the same local bias as weocumented here. Determining motion coherence or paf biological motion requires the observer to track multarts of the display and the relationship of the local elemith each other. Additionally, items must be integrated ac

ime and the difficulty may arise in this integration, juse have demonstrated a deficit in integrating local elemcross space. Thus, the motion deficit might potentiallyrise from the failure to derive a global configuration frtimuli3 containing multiple local elements and not fromhange in early visual processing per se.

We have suggested that the apparent slowing in orocessing, and to a greater extent in face processing mxplained by the local bias exhibited by the autistic indials. The relationship between the ability to configure l

3 On the surface, one possible exception to this is that Blake and colleBlake, Turner, Smoski, Pozdol, & Stone, 2003) report increased biologicotion thresholds in autistic children with preserved ability to group s

ine elements into a single global figure. This form of grouping, by collinty, is thought to be done by early visual processes (Kovacs, Kozma, Fehe

Benedek, 1999) and can be distinguished from the kind of higher-lerouping into identifiable shapes to which we are referring.

ant difficulty in integrating local components of a stimunto a whole. Moreover, this fundamental perceptual formrocessing is not restricted to faces but may impact vrocessing of other non-face objects too when the dem

or discrimination and recognition are high, as is true inase of faces. Because faces are typically identifiedxemplar-specific level, they are the most susceptible t

mpairment in integrating local elements, but commonects and novel Greebles are also affected, albeit not tame degree as faces.

In contrast with this view of weak perceptual coherer difficulty comprehending the spatial relationship betw

he elements perhaps by virtue of a local bias, otheres have argued that the face processing difficulties in aurise as a consequence of a social, rather than perceeficit. For example, it is known that individuals with autiave a limited capacity for social adaptation (Klin et al.,002) and orient more to objects than to faces (Dawson et al.004). But it is possible that the social deficit and the peptual disorder work in tandem: the lack of experiencehe inadequate attention to faces may limit the acquisf the normal configural perceptual skill. Consistent w

he claim that expertise comes to fine-tune or optimizeusiform gyrus (FG), the putative ‘face area’, as a funcf experience with a class of stimuli (Gauthier et al., sub

ed for publicationGauthier, Tarr, Anderson, Skudlarskore, 1999;Le Grand, Mondloch, Maurer, & Brent, 200),

he fusiform region of autistic individuals does not appntly come to respond preferentially to faces and thisoactivation may be a direct reflection of the social disab


(Schultz, 2005; Schultz et al., 2003). Some, although not all,recent functional magnetic resonance imaging studies haveshown reduced activation of the FG of autistic individualswhen viewing faces; instead strong activation is noted in theinferior temporal gyrus region, the region activated duringobject discrimination in controls (Grelotti et al., 2005; Hublet al., 2003; Pierce et al., 2004, 2001; Schultz et al., 2000).

We have, however, suggested an alternative interpretationand that it is that face processing is slowed not solely becausefaces are social but because they represent a particularly com-plex visual stimulus that depends specifically on configuralprocessing. This view is also supported by a recent study thatshows that face recognition is not correlated with ratings ofsocial impairment nor does it line up with a particular di-agnosis of social developmental disorder. Instead, as we do,the authors argue that any difficulties in face processing inindividuals with social deficits may well be causally relatedto an underlying perceptual alteration, suggestive of occip-itotemporal dysfunction (Barton et al., 2004). Whether theperceptual alteration is primarily responsible for the localbias and/or difficulty to derive configuration or whether itcomes from lack of experience with faces remains to be de-termined. Of course, the social disability and the perceptualperformance are not mutually exclusive and each may ulti-mately contribute both to the difficulties in processing facesand the difficulties in configural processing. The challenge ist aterd

7

tismb picala ell asi react tureo ver,w and,a undst ctedi entf wast werem ng inc ges.O ural-i dedp pli-c n thec datai elyd lowiE ingi iles d in-

stead, introduces questions about confounds that emerge fromartifacts of scaling (a problem that has plagued literature suchas that in the domain of schizophrenia). In some cases and insome of our paradigms, we have been able to show qualitativerather than simply quantitative differences. For example, inthe global/local task, the control subjects show global supe-riority whereas the autistic subjects exhibit local superiority.A second example is in the few/many task in which autisticindividuals (under the range of temporal intervals used here)never exhibit priming (equal or better performance on CSthan ES) when primes share configural representations withthe probe whereas this is evident in normal individuals bothearly and late with many element displays. However, the pat-tern of data in the face, object and Greeble tasks all indicateslowing in autism compared with control and understandingthe basis of this slowing will require further investigation.Converging evidence from studies using brief exposure andaccuracy may help in this regard.

An additional issue to confront is the apparent discrep-ancies between various measures in the paradigms we havereported. So, for example, while statistically significant groupdifferences may be observed (as in object and Greeble exper-iment), more detailed analyses do not always bear out thepredictions. It is also the case that not every individual autis-tic subject shows the full profile of perceptual differences(seeTable 2). These issues suggest that one might want toe eed,w thes

theres hesed in thep otorr refer-e alss herei ualsa t, im-p ighta er sea ught.

reta-t tisticg h theg ationl r in-t theh ysesa com-p mpa-r thatt tablet istica

ad-d sing

o understand their relative and joint contributions in greetail.

.3. Caveats and considerations

We have argued for an altered perceptual profile in auased on differences in reaction time between neurotynd autistic subjects in face and object processing as w

n configural processing. We have suggested that theseion time differences provide an important index of the naf visual processing in autism. Before concluding, howee need to consider some limitations of our approacht the same time, caution the reader to possible confo

hat might be at play. The experiments were all condun a ‘data-unlimited fashion’, i.e., the stimuli were presor an unlimited duration and our dependent measurehe speed with which the various perceptual decisionsade rather than the accuracy, as would be more telli

ases of displays with brief presentation of visual imaur approach, while advantageous in approximating nat

stic conditions where stimuli remain present for exteneriods of time, is potentially problematic, too. One comation is that just because autistic subjects are slower thaontrols does not obviously tell us whether the pattern ofn autism is qualitatively different rather than quantitativifferent. Indeed, autistic individuals are notoriously s

n their motor control and response time (Bauman, 1992).mphasizing the interaction (for example, greater slow

n condition B than A for autistics than for controls), whomewhat helpful, does not eliminate this quandary, an

-

xercise some caution in interpreting the data and, inde recommend that additional data be collected to verifytrength of the patterns we have observed.

Even if we set aside these statistical/technical issues,till remains the question of the mechanism underlying tifferences. As stated above, the differences could ariseerceptual system of autistic individuals or even in the mesponse system. The differences might also reflect a pntial strategy or cognitive style in which autistic individupend more time inspecting details in a situation when t

s no requirement for speed in a task. Why these individdopt this style or strategy still remains an open issue buortantly, if this were the case, the slowed performance mrise neither in the perceptual nor in the motor systems pnd an alternative approach entirely might need to be so

Another facet of the data that requires cautious interpion is that the match between the control group and auroups was not perfect. We had not been able to matcroups on IQ but matched on age and gender and educ

evel (as a rough but obviously not adequate proxy foellectual function). Although we analyzed the data fromighest functioning autistic individuals in some sub-analnd showed that the pattern of data remained unchangedared with the entire group analysis, the need for a coable intellectual group is pressing to ensure definitivelyhe patterns we see are specific to autism and not attribuo differential intellectual competence between the autnd control group.

A final, more theoretical question that remains to beressed is exactly what constitutes ‘configural’ proces


and whether the configural processing required for faces (andfor other objects) is the same as that required for global/localand few/many element processing. The definition of configu-ral processing is highly controversial and is the focus of manyinvestigations (Gauthier & Tarr, 2002; Leder & Bruce, 2000;Maurer et al., 2002; Moscovitch, Winocur, & Behrmann,1997). In the domain of face perception, one sense of ‘config-ural’ refers to the perception of relations among the featuresof a stimulus, with a distinction between two types of config-ural processing (Carey & Diamond, 1994; Rhodes, 1988): (i)first-order relations among elements, for example, process-ing the presence of two eyes above a nose and (ii) second-order relations—local elements are processed in a relationalmanner (e.g., nose–mouth distance). A second sense of theterm ‘configural’ refers to holistic processing—the featuresor local elements are glued together into a gestalt (Tanaka& Sengco, 1997). Although the distinctions are reasonable,many outstanding issues remain such as the extent of the su-peradditivity of the features in the holistic case, the abilityto access the local elements in the holistic case and the re-lationship between these different forms. Additionally, thesevarious configural processes are generally considered in rela-tion to faces (but see (Gauthier & Tarr, 2002)) and so apply-ing this taxonomy to the global/local task or to the few/manytask is less clear. Understanding what constitutes configu-ral processing, how the elements are represented in relationt pro-c urer figu-r ationi ntionp

A

theN cyM veP theN ismN

R

B ntive

B .uli.

B nor,ntaler and

B 002).nfig-

Bauman, M. L. (1992). Motor dysfunction in autism. In A. B. Joseph &R. R. Young (Eds.),Movement disorders in neurology and psychiatry(pp. 658–661). Boston, MA: Blackwell.

Behrmann, M., & Kimchi, R. (2003). What does visual agnosia tell usabout perceptual organization and its relationship to object percep-tion? Journal of Experimental Psychology: Human Perception andPerformance, 29(1), 19–42.

Behrmann, M., Avidan, G., Marotta, J. J., & Kimchi, R. (2005). Detailedexploration of face-related processing in congenital prosopagnosia: 1.Behavioral findings.Journal of Cognitive Neuroscience, 17(7), 1–19.

Beller, H. K. (1971). Priming: Effects of advance information on match-ing. Journal of Experimental Psychology, 87, 176–182.

Bertone, A., Mottron, L., Jelenic, P., & Faubert, J. (2003). Motion percep-tion in autism: A complex issue.Journal of Cognitive Neuroscience,15(2), 218–225.

Blair, R. J. R., Frith, U., Smith, N., Abell, F., & Cipolotti, L. (2001).Fractionation of visual memory: Agency detection and its impairmentin autism.Neuropsychologia, 40, 108–118.

Blake, R., Turner, L. M., Smoski, M. J., Pozdol, S. L., & Stone, W. L.(2003). Visual recognition of biological motion is impaired in childrenwith autism.Psychological Science, 14(2), 150–157.

Booth, R., Charlton, R., Hughes, C., & Happe, F. (2003). Disentan-gling weak coherence and executive dysfunction: Planning drawingin autism and attention-deficit/hyperactivity disorder.PhilosophicalTransactions of Royal Society of London. Series B: Biological Sci-ences, 358(1430), 387–392.

Boucher, J., & Lewis, V. (1992). Unfamiliar face recognition in relativelyable autistic children.Journal of Child Psychology and Psychiatry,33(5), 843–859.

Brosnan, M. J., Scott, F. J., Fox, S., & Pye, J. (2004). Gestalt processingin autism: Failure to process perceptual relationships and the implica-

C tions.

C Doities?

C ope:ex-

C fora pa-

C .,nalflow

C nter-

D erns-the

D Face

D , J.,nitionelay,

D ., etori-

o each other and whether the same form of configuralessing applies across all visual stimuli is critical for futesearch. Moreover, detailed understanding of the conal processing is autism remains elusive but its specifics a necessary precursor to developing targeted interverocedures.

cknowledgements

This research was funded by a grant fromICHD/NIDCD PO1/U19 to Marlene Behrmann (PI: Naninshew), which is part of the NICHD/NIDCD Collaboratirograms for Excellence in Autism and by grants fromational Alliance of Autism Research and the Cure Autow Foundation to Kate Humphreys.

eferences

acon, W. F., & Egeth, H. E. (1991). Local processes in pre-attefeature detection.Journal of Experimental Psychology: Human Per-ception and Performance, 17, 77–90.

adcock, C. J., Whitworth, F. A., Badcock, D. R., & Lovegrove, W. J(1990). Low-frequency filtering and processing of local-global stimPerception, 19, 617–629.

arton, J. J. S., Cherkasova, M. V., Hefter, R., Cox, T. A., O’ConM., & Manoach, D. S. (2004). Are patients with social developmedisorders prosopagnosic? Perceptual heterogeneity in the Aspergsocial-emotions processing disorders.Brain, 127(8), 1706–1716.

arton, J. J. S., Press, D. Z., Keenan, J. P., & O’Connor, M. (2Lesions of the fusiform face area impair perception of facial couration in prosopagnosia.Neurology, 58, 71–78.

tions for contextual understanding.Journal of Child Psychology andPsychiatry, 45(3), 459–469.

arey, S., & Diamond, R. (1994). Are faces perceived as configuramore by adults than by children?Visual Cognition, 1(2–3), 253–274

aron, M. J., Mottron, L., Rainville, C., & Chouinard, S. (2004).high functioning persons with autism present superior spatial abilNeuropsychologia, 42(4), 467–481.

ohen, J. D., MacWhinney, B., Flatt, M., & Provost, J. (1993). PsyscA new graphic interactive environment for designing psychologyperiments.Behavioral Research Methods, Instruments and Computers,25(2), 257–271.

rawford, J. R., & Garthwaite, P. H. (2004). Statistical methodssingle-case studies in neuropsychology: Comparing the slope oftient’s regression line with those of a control sample.Cortex, 40, 533–548.

ritchley, H. D., Daly, E. M., Bullmore, E. T., Williams, S. C. RAmelsvoort, T. V., Robertson, D. M., et al. (2000). The functioneuroanatomy of social behaviour: Changes in cerebral bloodwhen people with autistic disorder process facial expressions.Brain,123, 2203–2212.

umming, G., & Finch, S. (2005). Inference by eye: Confidence ivals and how to read pictures of data.American Psychologist, 60(2),170–180.

alton, K. M., Nacewicz, B. M., Johnstone, T., Schaefer, H. S., Gbacher, M. A., Goldsmith, H. H., et al. (2005). Gaze fixation andneural circuitry of face processing in autism.Nature Neuroscience,8(4), 519–526.

avies, S., Bishop, D., Manstead, A. S. R., & Tantum, D. (1994).perception in children with autism and Asperger’s syndrome.Journalof Child Psychology and Psychiatry, 35(6), 1033–1057.

awson, G., Carver, L., Meltzoff, A. N., Panagiotides, H., McPartland& Webb, S. J. (2002). Neural correlates of face and object recogin young children with autism spectrum disorder, developmental dand typical development.Child Development, 73(3), 700–717.

awson, G., Toth, K., Abbott, R., Osterling, J., Munson, J., Estes, Aal. (2004). Early social attention impairments in autism: Social


enting, joint attention, and attention to distress.Developmental Psy-chology, 40(2), 271–283.

Delvenne, J.-F., Seron, X., Coyette, F., & Rossion, B. (2004). Evidencefor perceptual deficits in associative visual (prosop)agnosia: A singlecase study.Neuropsychologia, 42(5), 597–612.

Ellis, H. D., Ellis, D. M., Fraser, W., & Deb, S. (1994). A preliminarystudy of right hemisphere cognitive deficits and impaired social judg-ments among young people with Asperger syndrome.European Childand Adolescent Psychiatry, 3, 255–266.

Farah, M. J., Tanaka, J. W., & Drain, H. M. (1996). What causes theface inversion effect?Journal of Experimental Psychology: HumanPerception and Performance, 21(3), 1–7.

Farah, M. J., Wilson, K. D., Drain, H. M., & Tanaka, J. R. (1995). The in-verted face inversion effect in prosopagnosia: Evidence for mandatory,face-specific perceptual mechanisms.Vision Research, 35, 2089–2093.

Foxton, J. M., Stewart, M. E., Barnard, L., Rodgers, J., Young, A. H.,O’Brien, G., et al. (2003). Absence of auditory ’global interference’in autism.Brain, 126(Pt 12), 2703–2709.

Frith, U. (2003).Autism: Explaining the enigma. UK: Blackwell Publish-ers.

Frith, U., & Happe, F. G. E. (1994). Autism: Beyond ‘theory of mind’.Cognition, 50, 115–132.

Gauthier, I., & Tarr, M. J. (1997). Becoming a “greeble” expert: Exploringmechanisms for face recognition.Vision Research, 37(12), 1673–1682.

Gauthier, I., & Tarr, M. J. (2002). Unraveling mechanisms for expertobject recognition: Bridging brain activity and behavior.Journal ofExperimental Psychology: Human Perception and Performance, 28(2),431–446.

Gauthier, I., Tarr, M. J., Anderson, A., Skudlarski, P., & Gore, J. (1999).Activation of the middle fusiform ‘face area’ increases with expertisefor recognizing novel objects.Nature Neuroscience, 2, 568–573.

G ition

G ficit

G airedition.

G . In

G J.,andtism.

G G.,oscil-

H ath,in

H vels:

H le?

H 98).

H s of

H sex-

Hobson, R. P., Ouston, J., & Lee, A. (1988). What’s in a face? The caseof autism.British Journal of Psychology, 79, 441–453.

Hubl, D., Bolte, S., Feineis-Matthews, S., Lanfermann, H., Federspiel,A., Strik, W., et al. (2003). Functional imbalance of visual pathwaysindicates alternative face processing strategies in autism.Neurology,61(9), 1232–1237.

Hughes, H. C., Fendrich, R., & Reuter-Lorenz, P. (1990). Global versuslocal processing in the absence of low spatial frequencies.Journal ofCognitive Neuroscience, 2, 272–282.

Jolliffe, T., & Baron-Cohen, S. (1997). Are people with autism and as-perger syndrome faster than normal on the embedded figures test?Journal of Child Psychology and Psychiatry, 38(5), 527–534.

Joseph, R. M., & Tanaka, J. (2003). Holistic and part-based face recog-nition in children with autism.Journal of Child Psychology and Psy-chiatry, 44(4), 529–542.

Kanner, L. (1943). Autistic disturbance of affective contact.NervousChild, 2, 217–240.

Kaufman, A. S., & Kaufman, N. L. (1985).Kaufman test of educationalachievement. Circle Pines, MN: American Guidance Service.

Kimchi, R. (1998). Uniform connectedness and grouping in the percep-tual organization of hierarchical patterns.Journal of ExperimentalPsychology: Human Perception and Performance, 24(2), 1105–1118.

Kimchi, R. (2000). The perceptual organization of visual objects: A mi-crogenetic analysis.Vision Research, 40, 1333–1347.

Klin, A., Jones, W., Schultz, R., Volkmar, F., & Cohen, D. (2002). Defin-ing and quantifying the social phenotype in autism.American Journalof Psychiatry, 159, 895–908.

Klin, A., Sparrow, S. S., de Bildt, A., Cicchetti, D. V., Cohen, D. J., &Volkmar, F. R. (1999). A normed study of face recognition in autismand related disorders.Journal of Autism and Development Disorders,29(6), 499–508.

K ation

L uli:tity.

L the

L tudy

L old-ized

L perturing

L Im-tion.

L : The

L g inntral

L hood,dard-

L ticare-ders.

authier, I., Behrmann, M., & Tarr, M. J. (1999). Can face recognreally be dissociated from object recognition?Journal of CognitiveNeuroscience, 11(4), 349–370.

epner, B., & Mestre, D. (2002). Rapid visual-motion integration dein autism.Trends in Cognitive Sciences, 6(11), 455.

erlach, C., Marstrand, L., Habekost, T., & Gade, A. A case of impshape integration: Implications for models of visual object recognVisual Cognition, in press.

insburg, A. P. (1986). Spatial filtering and visual form informationK. R. Boff, L. Kaufman, & J. P. Thomas (Eds.),Handbook of HumanPerception and Performance (pp. 1–41). New York: Wiley.

relotti, D. J., Klin, A. J., Gauthier, I., Skudlarski, P., Cohen, D.Gore, J. C., et al. (2005). fMRI activation of the fusiform gyrusamygdala to cartoon characters but not to faces in a boy with auNeuropsychologia, 43(3), 373–385.

rice, S. J., Spratling, M. W., Karmiloff-Smith, A., Halit, H., Csibra,de Haan, M., et al. (2001). Disordered visual processing andlatory brain activity in autism and Williams syndrome.Neuroreport,28(12), 2697–2700.

adjikani, N., Chabris, C. F., Joseph, R. M., Clark, J., McGrL., Aharon, I., et al. (2004). Early visual cortex organizationautism—An fMRI study.Neuroreport, 15(2), 267–270.

appe, F. G. E. (1996). Studying weak central coherence at low leChildren with autism do not succumb to visual illusions.Journal ofChild Psychology and Psychiatry, 37(7), 873–877.

appe, F. G. E. (1999). Autism: Cognitive deficit or cognitive styTrends in Cognitive Sciences, 3(6), 216–222.

auck, M., Fein, D., Maltby, N., Waterhouse, L., & Feinstein, C. (19Memory for faces in children with autism.Child Neuropsychology, 4,187–198.

obson, R. P. (1986). The autistic child’s appraisal of expressionemotion: A further study.Journal of Child Psychology and Psychiatry,27(5), 671–680.

obson, R. P. (1987). The autistic child’s recognition of age- andrelated characteristics of people.Journal of Autism and DevelopmentalDisorder, 17(1), 63–79.

ovacs, I., Kozma, P., Feher, A., & Benedek, G. (1999). Late maturof visual spatial integration in humans.Proceedings of the NationalAcademy of Sciences, 96(21), 12204–12209.

amb, M., & Robertson, L. (1988). The processing of hierarchical stimEffects of retinal locus, location uncertainty, and stimulus idenPerception and Psychophysics, 44, 172–181.

amb, M., & Yund, E. W. (1993). The role of spatial frequency inprocessing of hierarchically organized structure.Perception and Psy-chophysics, 54, 773–784.

angdell, T. (1977). Recognition of faces: An approach to the sof autism. Journal of Child Psychology and Psychiatry, 19, 255–268.

e Couteur, A., Rutter, M., Lord, C., Rios, P., Robertson, S., Hgrafer, M., et al. (1989). Autism diagnostic interview: A standardinvestigator-based instrument.Journal of Autism and DevelopmentalDisorders, 19, 363–387.

e Grand, R., Mondloch, C. J., Maurer, D., & Brent, H. P. (2003). Exface processing requires visual input to the right hemisphere dinfancy. Nature Neuroscience, 6(10), 1108–1112.

e Grand, R., Mondloch, C. J., Maurer, D., & Brent, H. P. (2004).pairment in holistic face processing following early visual deprivaPsychological Sciences, 15(11), 762–768.

eder, H., & Bruce, V. (2000). When inverted faces are recognizedrole of configural information in face recognition.Quarterly Journalof Experimental Psychology A, 53(2), 513–536.

opez, B., Donnelly, N., & Hadwin, J. A. (2004). Face processinhigh-functioning adolescents with autism: Evidence for weak cecoherence.Visual Cognition, 11(6), 673–688.

ord, C., Rutter, M., Goode, S., Heemsbergen, J., Jordan, H., MawL., et al. (1989). Autism diagnostic observation schedule: A stanized observation of communicative and social behavior.Journal ofAutism and Developmental Disorders, 19, 185–212.

ord, C., Rutter, M., & Le Couteur, A. (1994). Autism diagnosinterview-revised: A revised version of a diagnostic interview for cgivers of individuals with possible pervasive developmental disorJournal of Autism and Developmental Disorders, 24, 659–685.


Marotta, J. J., McKeeff, T. J., & Behrmann, M. (2002). The effects ofinversion and rotation on face processing in prosopagnosia.CognitiveNeuropsychology, 19(1), 31–47.

Martin, M. (1979). Local and global processing: The role of sparsity.Memory & Cognition, 7, 476–484.

Maurer, D., Le Grand, R., & Mondloch, C. J. (2002). The many faces ofconfigural processing.Trends in Cognitive Sciences, 6(6), 255–260.

McPartland, J., Dawson, G., Webb, S. J., Panagiotides, H., & Carver, L.J. (2004). Event-related brain potentials reveal anomalies in temporalprocessing of faces in autism spectrum disorder.Journal of ChildPsychology and Psychiatry, 45(7), 1235–1245.

Miller, M. B., Chapman, J. P., Chapman, L. J., & Collins, J. (1995). Taskdifficulty and cognitive deficits in schizophrenia.Journal of AbnormalPsychology, 104(2), 251–258.

Milne, E., Swettenham, J., Hansen, P., Campbell, R., Jeffries, H., &Plaisted, K. (2002). High motion coherence thresholds in children withautism.Journal of Child Psychology and Psychiatry, 43(2), 255–263.

Minshew, N., Goldstein, G., & Siegel, D. (1997). Neuropsychologicalfunctioning in autism: Profile of a complex information processingdisorder.Journal of the International Neuropsychological Society, 3,303–316.

Moscovitch, M., & Moscovitch, D. A. (2000). Super face-inversion ef-fects for isolated internal or external features, and for fractured faces.Cognitive Neuropsychology, 17(1–3), 201–220.

Moscovitch, M., Winocur, G., & Behrmann, M. (1997). What is specialabout face recognition? Nineteen experiments on a person with visualobject agnosia and dyslexia but normal face recognition.Journal ofCognitive Neuroscience, 9(5), 555–604.

Mottron, L., & Belleville, S. (1993). A study of perceptual analysis inhigh-level autistic subject with exceptional graphic abilities.Brain andCognition, 23, 279–309.

M T.singmul-

M l pro-

N atures

N gist’s

N hetcial

O 4).An

P t of

P brainform

P , E.a’ in

P t ex-ds.),

P dis-m

Plaisted, K., Saksida, L., Alcantara, J., & Weisblatt, E. (2003). Towards anunderstanding of the mechanisms of weak central coherence effects:Experiments in visual configural learning and auditory perception.Philosophical Transactions of Royal Society of London. Series B:Biological Sciences, 358(1430), 375–386.

Plaisted, K., Swettenham, J., & Rees, L. (1999). Children with autismshow local precedence in a divided attention task and global prece-dence in a selective attention task.Journal of Child Psychology andPsychiatry and Allied Disciplines, 40(5), 733–742.

Pomerantz, J. R. (1983). Global and local precedence: Selective attentionin form and motion perception.Journal of Experimental Psychology:General, 112(4), 516–540.

Rhodes, G. (1988). Looking at faces: First-order and second-order featuresas determinates of facial appearance.Perception, 17, 43–63.

Ricci, R., Vaishnavi, S., & Chatterjee, A. (1999). A deficit of interme-diate vision: Experimental observations and theoretical implications.Neurocase, 5, 1–12.

Rinehart, N., Bradshaw, J., Moss, S., Brereton, A., & Tonge, B. (2000).Atypical interference of local detail on global processing in high-functioning autism and Asperger’s disorders.Journal of Child Psy-chology and Psychiatry and Allied Disciplines, 41(6), 769–788.

Ropar, D., & Mitchell, P. (1999). Are individuals with autism and as-perger’s syndrome susceptible to visual illusions?Journal of ChildPsychology and Psychiatry, 40(8), 1283–1293.

Rouse, H., Donnelly, N., Hadwin, J. A., & Brown, T. (2004). Do childrenwith autism perceive second-order relational features? The case of theThatcher illusion.Journal of Child Psychology and Psychiatry, 45(7),1246–1257.

Schultz, R. T. (2005). Developmental deficits in social perception inautism the role of the amygdala and fusiform face area.InternationalJournal of Developmental Neuroscience, 23, 125–141.

S A.icaland

S C.,ocial

S ental

S ded

S rch

S e at-.

S Thelobal

S hil-

T ition.

T ration

T stic

T jects.

T s with

ottron, L., Burack, J. A., Iarocci, G., Belleville, S., & Enns, J.(2003). Locally oriented perception with intact global procesamong adolescents with high-functioning autism: Evidence fromtiple paradigms.Journal of Child Psychology and Psychiatry, 44(6),904–913.

ottron, L., Burack, J., Stauder, J., & Robaey, P. (1999). Perceptuacessing among high-functioning persons with autism.Journal of ChildPsychology and Psychiatry and Allied Disciplines, 40(2), 203–211.

avon, D. (1977). Forest before trees: The precedence of global fein visual perception.Cognitive Psychology, 9, 353–383.

avon, D. (2003). What does a compound letter tell the psycholomind? Acta Psychologica (Amsterdam), 114(3), 273–309.

jiokiktjien, C., Verschoor, A., de Sonneville, L., Huyser, C., OpVeld, V., & Toorenaar, N. (2001). Disordered recognition of faidentity and emotions in three Asperger type autists.European Childand Adolescent Psychiatry, 10(1), 79–90.

zonoff, S., Strayer, D. L., McMahon, W. M., & Filloux, F. (199Executive function abilities in autism and Tourette syndrome:information processing approach.Journal of Child Psychology andPsychiatry, 35(6), 1015–1032.

aquet, L., & Merikle, P. M. (1984). Global precedence: The effecexposure duration.Canadian Journal of Psychology, 38, 45–53.

ierce, K., Haist, F., Sedaghat, F., & Courchesne, E. (2004). Theresponse to personally familiar faces in autism: Findings of fusiactivity and beyond.Brain, 127, 2703–2716.

ierce, K., Muller, R. A., Ambroses, J., Allen, G., & Courchesne(2001). Face processing occurs outside the fusiform ‘face areautism: Evidence from fMRI.Brain, 124, 2059–2073.

laisted, K. (2000). Aspects of autism that theory of mind cannoplain. In S. Baron-Cohen, H. Tager-Flusberg, & D. Cohen (EUnderstanding other minds: Perspectives from developmental cogni-tive neurosciences (pp. 224–250). New York: Oxford Press.

laisted, K., O’Riordan, M., & Baron-Cohen, S. (1998). Enhancedcrimination of novel, highly similar stimuli by adults with autisduring a perceptual learning task.Journal of Child Psychology andPsychiatry, 39(5), 765–775.

chultz, R. T., Gauthier, I., Klin, A., Fulbright, R. K., Anderson,W., Volkmar, F., et al. (2000). Abnormal ventral temporal cortactivity during face discrimination among individuals with autismAsperger syndrome.Archives of General Psychiatry, 57, 331–340.

chultz, R. T., Grelotti, D. J., Klin, A., Kleinman, J., Van der Gaag,Marois, R., et al. (2003). The role of the fusiform face area in scognition: Implications for the pathobiology of autism.Philosophi-cal Transactions of Royal Society of London. Series B: BiologicalSciences, 358(1430), 415–427.

eitz, K. (2002). Parts and wholes in person recognition: Developmtrends.Journal of Experimental Child Psychology, 82(4), 367–381.

ekuler, A. B., & Palmer, S. E. (1992). Perception of partly occluobjects: A microgenetic analysis.Journal of Experimental Psychology:General, 121(1), 95–111.

hah, A., & Frith, U. (1983). An islet of ability in autism: A reseanote.Journal of Child Psychology and Psychiatry, 24, 613–620.

hulman, G. L., & Wilson, J. (1987). Spatial frequency and selectivtention to local and global information.Neuropsychologia, 18, 89–101

hulman, G. L., Sullivan, M. A., Gish, K., & Sakoda, W. J. (1986).role of spatial-frequency channels in the perception of local and gstructure.Perception, 15, 259–273.

ociety for Autistic Children. (1978). National society for autistic cdren definition of the syndrome of autism.Journal of Autism andDevelopment Disorder, 8, 162–167.

anaka, J. W., & Farah, M. J. (1993). Parts and wholes in face recognQuarterly Journal of Experimental Psychology, 46A, 225–245.

anaka, J. W., & Sengco, J. A. (1997). Features and their configuin face recognition.Memory and Cognition, 25, 583–592.

antam, D., Monaghan, L., Nicholson, H., & Stirling, J. (1989). Autichildren’s ability to interpret faces: A research note.Journal of ChildPsychology and Psychiatry, 30(4), 623–630.

arr, M. J., & Cheng, Y. D. (2003). Learning to see faces and obTrends in Cognitive Science, 7(1), 23–30.

eunisse, J., & De Gelder, B. (2003). Face processing in adolesentautistic disorder: The inversion and composite effects.Brain and Cog-nition, 32, 285–294.


Volkmar, F. R., Lord, C., Bailey, A., Schultz, R. T., & Klin, A. (2004).Autism and pervasive developmental disorders.Journal of Child Psy-chology and Psychiatry, 45(1), 135–170.

Wechsler, D. (1997).Wechsler intelligence scale (third ed.). San Antonio,TX: The Psychological Corporation.

Yin, R. K. (1969). Looking at upside-down faces.Journal of ExperimentalPsychology, 81, 141–145.

Yovel, G., Paller, K. A., & Levy, J. (2005). A whole face is more thanthe sum of its halves: Interactive processing in face perception.VisualCognition, 12(2), 337–352.

Documents

Configural processing in autism and its relationship to face processing