Psychiatry and Clinical Neurosciences

(2005),

59

, 4–10

Blackwell Science, LtdOxford, UKPCNPsychiatry and Clinical Neurosciences1323-13162005 Blackwell Science Pty LtdFebruary 2005591410Original Article

Noh Mask Test for schizophreniaS. Minoshita et al.

Correspondence address: Dr Seiko Minoshita, Department of Psy-chology, Kawamura Gakuen Woman’s University, 1133 SagetoAbiko, Chiba 270-1138, Japan. Email: mino@os.rim.or.jp

Received 29 May 2003; revised 2 June 2004; accepted 13 June 2004.

Regular Article

Recognition of affect in facial expression using the Noh Mask Test: Comparison of individuals with schizophrenia and normal controls

SEIKO MINOSHITA,

p

h

d

,

1

NOBUAKI MORITA,

md, p

h

d

,

2

TOSHIYUKI YAMASHITA,

p

h

d

,

3

MAIKO YOSHIKAWA,

md, p

h

d

,

4

TADASHI KIKUCHI,

p

h

d

5

AND SHINJI SATOH,

md, p

h

d

2

1

Department of Psychology, Kawamura Gakuen Woman’s University, Abiko, Chiba,

2

Graduate School of Comprehensive Human Sciences and

5

Institutes of Psychology, University of Tsukuba, Tsukuba, Ibaraki,

3

Tokyo Metropolitan Institute of Technology, Graduate School of Engineering, Intelligent Systems, Hino and

4

Department of Human Studies, Faculty of Human Studies, Musashino University, Nishitokyo, Tokyo, Japan

Abstract

The purpose of the present study was to compare facial expression recognition in individuals withschizophrenia and normal controls using the Noh Mask Test. Fifteen men with schizophrenia and15 normal controls were presented with a photograph of a Noh mask rotated either upward ordownward from the neutral front-facing position, and an emotion label, and were requested tojudge whether the expression of the mask was congruent with the indicated emotion. Using mul-tidimensional scaling, the facial expression of the Noh mask recognized by the patients and thehealthy controls was analyzed in 3-D: (i) Rejection–Attention; (ii) Pleasant–Unpleasant; and (iii)Awakening–Relaxation. Individuals with schizophrenia had difficulty recognizing that others hadintentions of harming them. The Noh Mask Test was found to be useful in discriminating betweenindividuals with schizophrenia and controls in the recognition of facial expression (discriminantratio: 99.9%).

Key words

discrimination test, multidimensional scaling, Noh Mask, recognition of facial expression,schizophrenia.

INTRODUCTION

In recent years, considerable research has investi-gated the perceptual disturbances of individuals withschizophrenia. Many studies exploring facial expres-sion recognition in these individuals have utilized rec-ognition tasks involving the identification of basicemotions, such as happiness, surprise, fear, sadness,disgust, and anger.

1–6

However, the appreciation ofsubtle affect has been found to be more importantthan the recognition of these basic emotions foremotional interactions in daily living,

7

and recognitionof subtle affect has been found to be impaired in

patients with schizophrenia.

8

A number of studieshave employed neutral facial emotion stimuli usingdifferent methodologies, including functional mag-netic resonance imaging (fMRI), event-related poten-tials (ERP) and electroencephalography (EEG).

9–14

The current study was designed to explore the recog-nition of subtle affective expression in individualswith schizophrenia. Previous studies have presentedpatients with line drawings or photographs of humanfaces, but such stimuli are not without problems.

15–17

Specifically, when line drawings are employed, thefacial expression may not realistically portray thefacial expression evident on the human face. Whenphotographs of human faces are used, personal char-acteristics of the models may confound the results.Such confounds include familiarity with the stimulusface and the examinee’s preferences for certain typesof faces. The current study employed photographs ofa Noh mask rotated to different angles as stimuli for

Noh Mask Test for schizophrenia 5

the assessment of facial expression recognition in aneffort to minimize the mentioned difficulties. A Nohmask is a mask worn by the leading dancer or protag-onist in a Noh play, a well-known traditional Japaneseperforming art. These masks combine elements of thehuman face in typical patterns, and their expressionsare considered to represent rich and diverse humanemotions.

18

The facial expressions of the female maskschange, depending on the angle from which they areviewed. These masks are designed to express conflict-ing emotions, in that when the face looks up, themouth appears as a chevron, expressing unpleasant-ness, but when the face looks down, the mouthexpresses pleasantness but the eyebrows and eyes areslanted inward to express unpleasantness. Therefore,the participants may need sophisticated judgment tohandle the contradictory information imparted by themask, in contrast to the largely consistent informationevident on an actual person’s face or a line drawing ofa face.

Given that the mechanisms involved in the recogni-tion of the Noh mask and the human face are notknown, there may be some argument as to whetherthey may be regarded as analogous. However, in a pre-vious study we administered a recognition task usingphotographs of a Noh mask as the stimuli,

19

and, viafactor analysis, were able to extract factors similar tothose extracted in studies that employed human facialexpression as the stimuli.

20

We have endeavored to create effective tools for themeasurement of the cognitive aspects of facial expres-sion in mentally challenged individuals for 10 years,with the result being the creation of a facial expressioncognition test. The stimuli of the test were created byhaving professional photographs taken of a Noh maskfrom the Taisho Era (1912–1926). The mask was fixedto a rotation stand, and the angle was changed sequen-tially by 1

∞

between shots, with a full lighting systemthat allowed every small change in facial expression toshow.

19

We then analyzed the responses of healthy con-trols to the mask by using factor analysis, and found thefeatures obtained in the Noh Mask Test, and thenextracted the emotion labels to be used in the test torefine the method of the Noh Mask Test.

21

The resultsof this method were then compared with findings of theYatabe–Gilford personality test (YG; specifically asthey relate to the anger scale), and we investigated therelationship between self-feeling and facial expressionrecognition.

22,23

We also analyzed the ambiguity of thefacial expressions of the Noh mask using a fuzzy rea-soning method to determine the possibility of creatingtools for a cross-cultural exchange.

24

As aforemen-tioned, we examined previous analysis methods andexperimental procedures.

METHODS

Participants

Fifteen men with schizophrenia and 15 healthy malecontrols participated in the present study. Individualsin the patient group were diagnosed with chronicschizophrenia according to

Diagnostic and StatisticalManual of Mental Disorders

(4th edn; DSM-IV) crite-ria, and were being treated as inpatients or outpatientsat a mental hospital when they participated in thepresent study.

25,26

Mean age of the patient group was33.2 years (SD

=

11.0 years), mean number of years ofeducation was 12.3 years (SD

=

1.7 years), mean ageat onset was 23.5 years (SD

=

5.2 years), mean dose ofchlorpromazine was 247.2 mg (SD

=

39.3 mg), andmean Brief Psychotic Rating Scale (BPRS) rating was11.3 (SD

=

7.4). Individuals in the control group werescreened for mental illness using the DSM-IV. Meanage was 31.6 years (SD

=

9.7 years), and mean numberof years of education was 19.3 years (SD

=

2.4 years).All participants gave informed consent to participatein the study.

Apparatus and stimuli

Stimuli were presented to the participants using a com-puter on a 17-in cathode ray tube (CRT) against ablack background. Each trial consisted of the presen-tation of an emotion label, followed by a fixation point,and finally a photograph of the Noh mask rotated toone of 15 different angles. Twelve emotion labels, spe-cifically those factors extracted in a previous study,were used in the present study: (i) surprise; (ii) sadness;(iii) happiness; (iv) interest; (v) composure; (vi) hope;(vii) shyness; (viii) curse; (ix) absence; (x) pride; (xi)ecstasy; and (xii) uncanniness.

21

Fifteen images of aNoh mask rotated from 50

∞

downward to 48

∞

upwardfrom the neutral position (down50, down40, down30,down20, down10, down6, down2, front, up2, up6, up10,up20, up30, up40, and up48) were used.

21

Procedure

The participants considered the photograph of a Nohmask in conjunction with the presented emotion labeland judged whether the expression of the mask wascongruent with the indicated emotion.

Practice trials consisted of the presentation of threemask images for each emotion label, and test trialsconsisted of 15 mask images for each emotion label.The three mask images for the practice trials wereselected from among the 15 test trial mask images.During the first and second practice trials, two partici-pants from the healthy control group requested elabo-

6 S. Minoshita

et al.

ration of the meaning of the emotion labels, while fiveparticipants from the patient group requested assis-tance with the meaning of the emotions. Also, someparticipants from both groups were uncertain abouthow to press the keys until the second practice trial. Inthe third practice trial, however, all the participantsexecuted the test without hesitation. One patient hadno difficulty during the practice trials but discontinuedthe test in progress, stating, ‘I want to stop the testbecause I’m tired’.

In each trial, an emotion label was presented for500 ms, followed by a fixation point presented for500 ms, followed by the photograph of the Noh mask,which remained on-screen until the participants madetheir judgment of emotion–mask congruence by press-ing the corresponding key. Subjects were instructed toconsider the emotion label and Noh mask image pre-sented in each trial and to press the ‘yes’ key when theyfelt that the Noh mask image expressed the presentedemotion and the ‘no’ key when they felt that it did not.Each participant completed 180 trials (12 emotionlabels

¥

15 mask images). Completion of all trials tookapproximately 30 min for individuals in the controlgroup and approximately 40 min for individuals in thepatient group.

Analysis method

Plots for assessment of stimulative images by the multidimensional scaling method to investigate the plot of recognition of facial expression

The disparity matrix was given to route the number ofall pairs of judgments concerning the 30 stimulationimages by the multidimensional scaling program,

alscal

.

27

As we analyzed the image of the Noh maskfor each group by angle, the results for each item weretreated as data points, therefore total data points wereas high as 30 persons

¥

12 items

=

360 (apparent). Thedata matrix shape was symmetrical at 30

¥

30 dataitems. The model option chosen was Euclid.

Differential diagnosis

The discriminate analysis was performed by enteringall items (12 labels and 15 photos), seven affect labels[(i) surprise; (ii) sadness; (iii) happiness; (iv) compo-sure; (v) shyness; (vi) absence; and (vii) uncanniness],which are basic affect labels (i–iii) and have significantdifferences between schizophrenia and normal con-trols (iv–vii), and nine photographs (down40, down30,down20, down10, front, up10, up20, up30, up40), threelabels [(i) surprise; (ii) sadness; (iii) happiness], whichare basic affect labels, and nine photographs.

RESULTS

Plot of the results of the two groups of Noh Mask Test

The value of SSTRESS as a 2-D solution was 0.287,while the value of SSTRESS was 0.161 when it wasmapped in 3-D coordinates. We selected 3-D analysis,because SSTRESS (Stress by Young’s formula) wasimproved markedly and interpretation was easier. Thegraphs in Figs 1,2 show the plots on 2-D coordinates.

Using 1-D analysis, we examined the rates of emo-tional affirmation of the positive high scores of controls(C) for different positions of the Noh mask (down, d;up, u): Cd50, Cd40, Sd50, and Cd30 [where the number(50, 40 etc.) refers to the angle in degrees] and the neg-ative high scores of Cu06, Cu10, Cu02, and Cd02. Wefound that the affirmation rate of the positive highscore image was high in ‘Curse’ while that for the neg-ative high score image was high in ‘Interest.’ Thus, wenamed the 1-D scale as ‘Attention–Rejection’.

Using 2-D analysis, we examined the rates of emo-tional affirmation of the positive high scores of schizo-phrenia patients (S) for Noh mask positions of Sd30,Sd40, Sd50, and Sd10 and the negative high scores ofCu30, Cu40, Cu50, and Cu20. We found that the affir-mation rates of the positive high score images werehigh in ‘Composure’, ‘Hope’, and ‘Shyness’ while thoseof the negative high score images were high in ‘Uncan-niness’, ‘Surprise’, ‘Sadness’, and ‘Curse.’ Thus, wenamed the 2-D scale ‘Pleasant–Unpleasant’.

Using 3-D analysis, we examined the rates of emo-tional affirmation of the positive high scores of Cd20,Cd30, Cd06, and Cd10 and the negative high scores ofSu30, Su40, Su50, and Su20. We found that the affirma-tion rates of the positive high score images were high in‘Composure’, ‘Interest’, ‘Happiness’, ‘Hope’, and ‘Shy-ness’ while those of the negative high score imageswere high in ‘Surprise’, ‘Ecstasy’, ‘Composure’, and‘Uncanniness.’ Thus, we named the 3-D scale as‘Awakening–Relaxation’.

Differential diagnosis

Plot of the results of two the groups of Noh Mask Test

The discriminant analysis was performed entering allitems into the equation to raise the discriminant ratioto 99.9%. We are able to achieve a determinant ratio of99.9% using a modified version of seven affect labels[(i) surprise; (ii) sadness; (iii) happiness; (iv) compo-sure; (v) shyness; (vi) absence; and (vii) uncanniness]and nine photos (down40, down30, down20, down10,front, up10, up20, up30, up40) out of the original item

Noh Mask Test for schizophrenia 7

set. Utilizing this reduced set of stimuli would reducethe amount of time required to complete the NohMask Test.

DISCUSSION

Plot of the results of the two groups of Noh Mask Test

These results agree with the Pleasant–Unpleasant,Attention–Rejection, and Awakening–Relaxation fac-tors described in the facial expression circle model pre-sented by Schlosberg, and are consistent with themajor dimensions of emotion recognition obtained bydimensional evaluation methods in the study of facialexpressions.

28–30

In Fig. 1, the plotted stimulative images created anearly circular pattern using 2-D coordinates (mappedwith the first dimension as the X axis and the seconddimension as the Y axis) in the controls. In contrast, theplotted images created a semicircular pattern, with the‘unpleasant’ side flattened, in the patients. This sug-gests that patients with schizophrenia have difficultyperceiving unpleasantness and attention of facialexpressions on a Noh mask and tend to infer pleasant-ness and attention instead. In other words, patientswith schizophrenia may have difficulty in recognizingothers’ ill-wishes towards them. This result may be con-sistent with the finding that patients with schizophreniahave difficulty recognizing unpleasant emotions, whichhas been documented using imaging technology suchas fMRI.

31

Figure 1.

Multidimensional scale plots of the reaction of control group and schizophrenia group for Noh mask stimulus(dimension1, dimension2). The stimulus images were plotted in a nearly circular pattern in 2-D coordinates (mapped with thefirst dimension as the X axis and the second dimension as the Y axis) in the controls, but in a semicircular pattern with theunpleasant side flattened in the patients. Cu10, images presented to healthy controls with an upward angle of 10

∞

; Cd20, imagepresented to healthy controls with a downward angle of 20

∞

; Su30, image presented to schizophrenia patients with an upwardangle of 30

∞

; Sd40, image presented to schizophrenia patients with a downward angle of 40

∞

.

Su50Su40Su30

Su20Su10

Su06Su02

SfrontSd02

Sd06

Sd10

Sd20

Sd30Sd40

Sd50

Cu50Cu40

Cu30Cu20

Cu10

Cu06Cu02

Cfront

Cd02

Cd06Cd10 Cd20

Cd30

Cd40

Cd50

3210-1-2

2.0

1.0

0.0

-1.0

-2.0

-3.0

Attention-RejectionDimension 1

Unp

leas

ant-

Ple

asan

tD

imen

sion

2

Schizophrenia(S)

Control(C)

8 S. Minoshita

et al.

Also, the plotted stimulative images for the patientand control groups, depicted in Fig. 1, suggest that theinterpretation of the facial expression varied mostwhen the mask was facing front (i.e. not rotatedupward or downward). The clues available to the par-ticipants in the present study for interpretation ofexpressions were the angle of inclination of the maskand protrusions and depressions of the face with con-sequent shadows. The inclination of the Noh maskimages was not changed at even intervals in thepresent study; the changes were smaller near the neu-tral front position (up6–down6) and larger in the up-turned (up50–up10) or down-turned (down 10–down50) positions. When the participants perceivedthe expressions of the Noh Mask near the front, theinformation from mask inclination was limited, andthe protrusions and depressions of the face and result-ant shadows were the only types of information avail-able. Therefore, it could be argued that the ‘vagueness’of the stimuli was increased in this position, and thatthe expression of the Noh mask image became subtler.The controls perceived subtle differences from thecontrast of shadows, while the patients did not per-ceive the subtle differences. The results of the presentstudy also are considered to support the reports thatpatients with schizophrenia are poor in perceivingvague stimuli.

32–34

This technique may be applied to social skill training(SST) by pointing out to individuals with schizophre-nia their tendency to distort facial expressions of oth-ers, which may affect their social interactions in dailyliving.

Differential diagnosis

In recent years, there have been many attempts to dif-ferentiate healthy controls from schizophrenia patientsbased on the difference in their ability to recognizefacial expressions. However, no previous study wasable to produce the high rate (99.9% accuracy) of clas-sification achieved in the current study. While manystudies of the recognition of facial expression have uti-lized photographs of human faces and line drawings,the present research used Noh masks that combine eth-nic and cultural information. Unlike stimulated images,which represent emphasized or simplified humor, andwhich have been in the form of human photographs orline drawings in the past, Noh masks represent facialexpressions that are more complicated and provideinconsistent information. The high discriminability rateachieved in the present study may be attributed to theinherent ambiguity present in Noh masks that presentcomplicated and subtle emotions. The ambiguity ofNoh masks may shed light upon the pathology ofschizophrenia patients in the same manner in whichprojective tests, such as the Rorschach test, draw outdysfunction in individuals with mental illness. Previousfindings by the author revealed that the Rorschach testwas better than any other procedure in differentiatingbetween disease type, while the Noh Mask Test was thebest predictor of employment status 4 years later. Inthat study, we did not utilize a forced-choice method ofselecting the emotional label.

35

Instead, we asked par-ticipants whether a certain facial expression ‘looked so’or ‘did not look so’. We thought that this method wasuseful for participants to reply ‘yes’ by taking reflectioninto account when the participants felt that a certainfacial expression did not clearly ‘look so’.

Future tasks

Given the results of the current research and the bur-den load on the patients, future research would be bestaccomplished using a shortened version of the NohMask Test. We plan to increase the number of partici-pants to confirm the reliability and validity of the NohMask Test, and also plan to collect data for a number ofother disorders. We already have conducted compari-sons with a person’s facial stimulative images and linedrawings for the healthy controls.

36

Also, comparison

Figure 2.

Multidimensional scale plots of the reaction of thecontrol group and schizophrenia group for Noh mask stimu-lus (dimension2, dimension3). The plotted stimulative imagesfor schizophrenia and control groups showed that those twogroups were divided clearly. Cu10, image presented tohealthy controls with an upward angle of 10

∞

; Cd20, imagepresented to healthy controls with a downward angle of 20

∞

;Su30, image presented to schizophrenia patients with anupward angle of 30

∞

; Sd40, image presented to schizophreniapatients with a downward angle of 40

∞

.

.5

Aw

aken

ing-

Rel

axat

ion

Pleasant-UnpleasantDimension 2Dim

ensi

on 3

1.51.0.50.0-.5-1.0-1.5-2.0-2.5

2.0

1.5

1.0

0.0

-.5

-1.0

-1.5

-2.0

Su50

Su40Su30

Su20

Su10Su06Su02

SfrontSd02

Sd06

Sd10

Sd20 Sd30Sd40

Sd50

Cu50

Cu40

Cu30Cu20

Cu10 Cu06

Cu02 CfrontCd02

Cd06Cd10

Cd20

Cd30Cd40

Cd50

Schizophrenia

Control

Noh Mask Test for schizophrenia 9

with other facial stimulative images is being carried forpatients with schizophrenia.

CONCLUSION

Using the Noh Mask Test, we were able to demon-strate differences in the ability to recognize facialexpression in patients with schizophrenia versus con-trols. Three dimensions were extracted using the mul-tidimensional scaling method. The plots of the controlgroup and the patient group suggested that healthyparticipants perceived emotions such as pleasantness,attention and tension from the Noh mask images.In contrast, patients with schizophrenia perceivedemotions such as unpleasantness, attention and sleeprelatively frequently. The possibility of using the NohMask Test as a diagnostic instrument for schizophreniais proposed.

ACKNOWLEDGMENT

This study was supported by Grant-in-Aid for Scien-tific Research (C) No.10835002, No.12670922 in Japan.

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