The influence of duration on the perception of gaze direction and being looked at(Summaries of Awarded Presentation at the 28th Annual Meeting)

The Japanese Psychonomic Society

NII-Electronic Library Service

The JapanesePsychonomic Society

V'he_{JaPaneseJ?)umal}oflts'.vchonomicScience

20IO,Vol.29,No.],69 70

Summary

ofAwarded

Presentation5-113

The

influence

of

duration

on

the

_perception

of

_gaze

direction

and

being

looked

at

Yutaka

NAKAJiMA*,

Yusuke

TANI*2,

Yuko

IsoGAyA*2,

and

Takao

SATo*2

lhe

Uhiversits,

of

Toleyo'･

*2

To investigatehow quickly we can _perceive being watched by other _people,we evaluated the

effect of

duration

on the quantitative

judgment

of gaze

direction

and the perception of "being

Looked at", The stimu!i were models ef heads _generated by acomputer, and thcrotation angle and

gaze directionof each head was varied indepenclently,

The

participants were asked to

judge

whether the stimulus was looking at them

(being-looked-at

judgment),

and to

judge

where the

stimuLus was looking

(quantitative

_gaze direction

judgment).

The

resu]ts revealed thatneither the

direction

thatgives the

best

perception of

being-looked-at,

nor the perceptually straight

direction

of the _participantswere affected by the duration

(100

ms, 1000 ms, or an unlimited duration}.

These results indicatethatthe

judgment

of whether or not a

looker's

gaze

is

directed

towards one completes at an early

level

in

thegaze perception process and within

100

ms.

Key

words: _gaze

directien,

_perception of

being

looked

at,

duration.

The _perception of "being _looked

at"'

is

one of the

important

methods of communication, It

is

known

thata _person who islooked at _perceivcs a looker's

gaze as

"being

looked at" when the looker'sgaze

is

directedtotheir

faee

(Gibson

& Pick.1963)or within

3

degrees

of theirnose.

The

perception

is

also

inde-pendent of theviewing clistancc

(Sato

&

Matsuzaki,

2eOl). Not only the _gaze itselL

but

also the looker's

head

rotation affeets the

_gaze

_perception.

When

the tooker'shead isturned to therighL the _gaze direction

that _givesthe best"being-looked-at"

feeling

shifts to

the left,relative tothat of a frontal direction,and

vice versa

(the

head-turn effect,

Anstis,

Mayhew,

&

Morley,

1969).

As

noted abovc, _prev]'ousstudies

have fecused on the spatial _property of _gaze

percep-tion,

but

few

have

investigated

the temporal

prop-erty. Two _questions may beasked. First,does the

"being-looked-aC'

perception occur after the

judg-ment of gaze

direction?

Or,

does

the processing of

thisperccption and the

judgment

of the looker's_gaze

directionoccur simultaneously?

The _purpose of this study was to examine the

temporal property of _{gaze perception} by varying the

presentation time

(duration)

of a stimulus.

The

par-* _{IntelligentMode]ing Laboratory, The}

Universi-ty of Tokyo, 2ml1-16,Yayoi,Bunkye-ku, Tokyo

113-8656

Copyright201O,The

japanese

Psychonomic Society

ticipantsperforrnedtwo tasks,

The

first

was to

judge

whether or not the

_gaze

was directedtowards them

(being

looked at, or not). The second task was _to

quantitatively evaluate the gaze angle.

The

results

of these tasks were compared, so that the

relation-ship

between

theperceptionof

"being

looked

at"and

gaze directioncould bcclarified.

Methods

Four types

₍₂

males and 2females) of head models

were _prepared in Poser 7

(Srnith

Micro

Software,

Inc.),and used as stimuli. They were _presented ina

random ordcr on a

17-inch

CRT

display

inall

experi-mcnts. We varied thehead rotation angle and gaze

direction

of the models independent]y, The rotation

angles were

-30,

-15.

0,

+15, and

30

degrees,

and

the _gaze djrectionswere

-18,

-15,

-12,

-9,

-6,

-3,

_{O, +3, +6, +9,} +12, _+15, and +18 degrecs,

respectively.

We

defined

the straight-ahead

direc-tiontothc participantsas Odegree.

Positive

values

indicated a head rotation towards the right, and

negative values to-,ards the left,from the partici-pants'viewpoinL

The

sizeof thestimuli was close to

an actual human

head

size.

The

durations

were

fixed

within each experimental block and was 100ms,

1OOO ms, or unlimited. Fer the being-looked-at

judg-ment, the participantsused

3AFC

method

(leftward,

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The JapanesePsychonomic Society

70

The

Japanese

Journal

of Psychonomic

Science

Vol,

"being _looked

at", rightward} to

judge

whether the stimuLus was

looking

at them.

Each

stimu]us was presented 20 times. For the quantitative gaze

direc-tion

judgment,

they were asked toestimate the _gaze

direction

by

moving a marker placed

in

front

of them

(cf.

Anstiset al. 1969),Each stimulus was _pre$ented

4

times.

Eight

(being-looked-atjudgments)

orsix

(gaze

direction

judgments)

naive participantswith normal or corrected-to normal vision participated.

All

of

the

experiments were conducted ina dark room.

Results

For the being-looked-at

judgrnent,

we first

calcu-lated

the ratio of the

being-looked-at

rcsponses

for

each condition and participant, We then estimated

the

perceived gaze

direction

of

the

looker and

the

maximum ratie of the _perceived

being-looked-at

re-sponse, by

fitting

Gaussian functions to the

calcu-lated

data,

The averaged

data

across allparticipants

are shown

in

Figure IA. These results show thata

differenceof

duration

dicl

not affect the _perceived

gaze

directien

of the looker.

In

addition, the

maxi-mum ratio at a

duration

of 1OO ms was significantly

lower

than at any other

duration,

especially when

the

head

orientation was ±

30

degree,

For thequantitativeestimation, we calculated the

average of the

_judged

gaze

direction

for

each

_-?

A

e .ts! 2.

ii?

ek

1

ls 3b

ISio

Ee.E

tio.1lg r os

Feee engla _(deg}

Figure 1.

Results

of receivedjudgments. ments. iIi･lli

_t/

;..-.i.;Ii':'-./xtt..-//-i'tttttt;ttt;t.t.ttl.t/･,gli:'

.''={l,1..Ll'

''t-tt:rr,:i'

'' 11,{

''i'fr.{i''

"a-{salssu -s

g,

i,

gl

B

15

}i'

v

.30

"15

O 15 Feoeangle{deg) experiments.

A.

gaze-B.

gaze-directien

judg-se

29,

No.

1

tion and participant,and estimated the perceived

straight djrection

(which

we defined as a _perceptual zero

clirection)

and regression coeMcient

_(which

is

regarded as accuracy index) with

liner

regression

from

the

averaged

data.

The

averaged

data

across

participantsare shown inFigure IB. These results show that the

duration

did not have a significant

effect on a perceptual zere

direction,

whereas the

regression coethcient at a

duration

of

100ms

was

significant]y Iower than at any other

duration.

Discussion

Our results suggest thatittakesup to 100ms to

aceomplish the

judgments,

whether or not the_gaze

of a looker

is

directed towards oneself.

This

is

be-cause both

the

gaze direction that gives the be$t

being-looked-at

responses and the perceptual zero

directionwere not affected

by

a

difference

of

dura-tion.

The

decrease

of the ratio of

being-looked-at

responses fora duration of

100

ms and

for

rotated

heads might be related to the higher accuracy of

quantitative

judgment

at the

100-ms

duration.

When thedurations were 1OOO ms andlor unlimited,

the gaze

direction

judgrnents

were less accurate:

more precisely,overestimation of the

looker's

gaze directionoccurred at thesedurations. This

overesti-mation may serve to

distingui$h

a _gaze toward and

away

from

_{participants,}which leadstoimprovement

of the

S/N

ratio.

Accordingly,

we propose thatthe

discrete

judgment

of whether or not alooker'sgaze

is

directed

toward one, would eccur at an earlier level

than the

level

where the precisequantitativc

judg-ment takesplace. The results of such a quantitatjve

judgment

may feed back and modify the final

per-ception of _gaze direction.

References

Anstis,

S.

M.

Mayhew,

J.

W.

&

Morley,

T.

{1969).

The perceptionof where a

face

or television"portrait"

islooking.American

fournat

of

Rsychoiogy,82,

489.Gibson,

J.

J.

&

Pick,

A.

D.

(1963),

Perception of

other _person's

looking

behavior.

American

lbunzat

of

Rsychotogy,

76,

386-394,

Sato,

T,,

&

MatsuzakL

N,

{2001},

Effects

of viewing

distance

and image blurring on _{gaze perception.}