1-B-34「こちらを向いた視線」からは目が離せない? : Gap効果を用いた検討(2002年度 日本基礎心理学会第21回大会優秀発表賞)

The Japanese Psychonomic Society

NII-Electronic Library Service

The JapanesePsychonomicSociety

1'hejaPanesefournalofIlsvch(momicSc'ience

2003, Vol.22,Ne. 1,33-34

Prizewinner's

Summary1-B-34

Is

itdiMcult

to

An

look

away

from

the

examination

using

adirect

gaze

of

another

_person

?

temporal

_gap

effect

AtsushiSENJu

and

Toshikazu

dniversit3,

of

Tokyo*HASEGAWA

We investigated whether the

direct

_gaze of another _person captures attention and delays

attentional

disengagement

from

a face in an experimental situation. The _participants wcre required to

fixate

on thecentrally _presented facewith varying gaze

direction

and required spceded

detection of the _{peripheral]y presented} target. The results rcvealed that target

detection

was

delayed ina

direct

gaze condition

but

not

in

an averted

_gaze

or with a closed eycs condition. This

effect,

however,

disappeared

when a temporal _gap was insertedbetween theoffset of thecentral

face

and the onset of the _peripheral

targct,

suggesting a contribution of an attentional and/or oculomotor disengagement fora de]ayed response

following

a

direct

_gaze, Morcover, a direct_gaze rnade an effect only with a stimulus onset asynchrony

(SOA)

of 500 rns and disappeared with an

SOA

of

1,200

ms,

This

result

implied

thattheeffcct of a direct_gaze is_transient.

Key words: direct_gaze,attentional

disengagement

gap effect

The

direct

gaze of another person signals their

intention

toward theobserver and thus conveys

cru-cial information regarding social

interaction,

A

di-rect _gaze isalso

detected

faster

_(von

GrUnau &

An-ston,

1995).

The

_present

study

investigated

whether

perception of a direct_gaze also captured attentien

and made itdithcultto disengage from the gazing face. Because a direct_gaze

is

_quite an

important

signal, a centrally presented

face

with a

clirect

gaze

was _predictedtocapturc an observer's attention and

make itdithcult

to

respond

to

any stimuli outside the facialarea.

Method

Participants Six university students

partici-pated

in

this

study.

All

had

normal or corrected

normal visual acuity.

Apparatus and stimuli The experimcnt used

Ce-drus SuperLab software on a

Dell

OptiPlex

GX50

computer with a

17-inch

CRT

monitor

_(SONY

Multi

scan E230). The

head

of each _participantwas fixated

by

a chin rest at a distanceof 57cm from the

rnoni-tor, The reaction times

(RT)

of theparticipantsand *

_Department

_of

_Cognitive

_{and Behavioral Science,}

Graduate

School of Arts and

Sciences,

The

Univer-sity of Tokyo, 3L8-1 Komaba, Meguro-ku, Tokyo 153-8902

theiraccuracy were mcasured

from

keyboard

re-sponses. The

fixation

_pointwas a central cross

sub-tended at an anglc of O,350, The targetstimulus consisted of an asterisk subtended at an angle of

O,70

and _positioned12.50tothe leftor right of the

fixation

point.

The

same type of

image

was used to_produce

threetypes of facialstimuli on which theeye region of other _pictures

(with

direct,avertcd, or closed eyes}

of the sarne _person were superirnposed. The irnages

of the

faces

were

displayed

in

full

color and cut into an oval shape which measured 6.5ewide and 10"

high.

Design

There

were three within-participant

fac-tors:thegaze

direction

(direct

gaze, averted gaze or closed eyes); the trialtype

(gap

condition or overlap condition); and thestimu]us onset asynchrony

(SOA)

between the facialstimuli and target

(500

or

1,200

rns),

Proeedure

At

the beginning of each trial a fix-ation cross appeared in the center of _the screen.

Parttcipantswere asked

to

fixate

on thiscross and to

maintain

fixation

at thecenter of thescreen

through-out the experiment. After a delay of

500ms

the

fixation

cross was replaced by one ofthe

facial

stim-uli, which was

di$played

slightly

below

theccnter of

the screen so that

its

eye region could appear

just

to

the center. Following the SOA

{500

or 1,200ms) a

The Japanese Psychonomic Society

NII-Electronic Library Service

The JapanesePsychonomic Society

34 The

Japanese

Journal

of Psych

.onomlcScience

Vol,22,No, 1

Table

1

Median reaction tirnes

{mean

±

SD,

inms).

Stimulus onset asynchrony

500 ms

1,200

ms

Direct

gazeAverted gazeClosed eyesDirect gazeAverted gazeClosed eyes

GapOverlap266,3

±22,1

319,6

±22.1271.8 ±22,7

306.3

±23.8273,5 ±

18,7

309.0±_19,4285.0 ±

31,O

301.3±_25,O284,8 ±

26,O

299.8±_30.1283,4 ±

33.9

292.9

±

24.3

targetasterisk appeared randomly either tothe

left

or to

the

right

(with

an equal _probability)of the'

ccntral fixation point. The participants were

re-quired todetectthe target,and then pressthespace

bar on the keyboard as quickly as possible, Inthe

gap condition,

the

central

face

disappeared

250ms prior tothe appearance of thetarget.Incontrast, in

theoverlap condition the

display

of the

facial

stimuli was kept on

the

screen. The _participantscompleted

five blocks of 120 trials. Each block consisted of eight repetitions of each of 12 experimental

cendi-tionsand a set of

24

"catch" trials

in

which a target

was not _presented. During thecatch trialsthe

par-ticipantswere required

to

refrain from key pressing. Feedback was _presented on the screen

following

each response. The firstblock of trialswas regarded as a practice

block

and was not used in

the

analysis.

The

trialswere randomized within allblocks.

Results

and

Discussion

The

inter-participant

means of themedian reaction

times

(RTs)

are presented

in

Table

1.

We

used a

three-way analysis of variance

(ANOVA}

with _gaze

direction

(direct

gaze,averted _gaze,or closed eyes),

trialtype

(gap

condition, or overlap condition) and

stimulus onset asynchrony

(SOA)

between

the

facial

stimuli and the target

(500

or

1,200ms).

A

main

effect of

trial

type

was significant

(F[1,

5];52.52,p<

O.Ol),

which

indicated

a

faster

RT

for

the

_gap

con-dition

(gap

effect). The

interactions

between

the gaze

direction and trialtype

{F[2,10]=15,20,

P<O.Ol)

were also significant. A simple effect testrevealed

thatthegaze

direction

had

asirnple main effect only

intheoverlap condition

{F[2,

1O]=7.40,p<O.O1}

but

not

in

the

_gap condition

{F[2,

10]=O,75,P>O.1).

To

examine the effect of direct_gaze,a _priori compari-sons were conducted with

Dunn's

_procedure.

In

the

overlap condition, target detection took longer in

response to

direct

gaze than toan averted gaze

(p<

O,05)and toclesed eyes

(p<O.Ol).

Further analyses revealed that

direct

gaze slowed down target

detec-tion more than averted gaze

(P<O.Ol)

and closed

eyes

(P<e.05)

at an

SOA

of

500

ms,

but

not at an

SOA of 1,2eOms.

The

interactions

between

thetrial

type and SOA

{F[1,

5]=35.76,p<O.O1), and between

the gaze

direction

and

SOA

(F[2,

10]=6,27,p<O,05}

were also significant.

The results revealed thatRT was slower when the

central

face

was

in

the

direct

_gaze condition, which suggested that

direct

gaze captures attentional and!

or oculemotor engagement and delays

disengage-ment. In addition, this effect was not

found

in

the

gap condition, perhaps

because

the

temporal gap had

allowed participants to rcflexively

disengage

from

the _gazing face, Moreover, the effect of the

clirect

gaze was not observed with a longer

SOA,

which

seemed to

indicate

a transientnature of the delayed disengagement from the directgaze.

Furthermore, our recent study

has

revealed that

such a

delayed

disengagernent

inresponse toa direct

gaze

diminished

when the contrast polarityof the esie region was reversed, and thus the _gaze

percep-tionwas disrupted

(Senju

& Hasegawa, submitted for

publication).

The

results suggest

that

gaze percep-tion plays a critical role

in

an attentional andlor oculomotor capture oL and

delayed

disengagement

from,

another person'sdirectgaze.

References

von Grtinau,M. & Anston,

C.

1995 The

detection

of

gaze direction:a stare-in-the-crowd effect.

Plercop-tion,

24,

1297-1313.

Senju,

A.,

&

Hasegawa, T.Direct_gaze captures