図と地のパタン変化による明るさ知覚(第23回大会 優秀発表賞抄録)

The Japanese Psychonomic Society

NII-Electronic Library Service

The JapanesePsychonomic Society

The jLepaneseJoutnatofAipuehonomicScience

2005,VoL 24,No. I,1t]-112

Summary

ofAwarded

PresentationIP09

Stronger

influence

of

_ground

on

the

_perceptual

lightness

_of

a

space

surrounded

by

figure-ground

scission

_patterns

Yui

YAMAGucHI

and

Ken

SHIrNA

University

of

Tsuhuba*

We investigated the

impression

of an overall ]ightnessof a space surrounded

by

wallpaper

where thetotal area o"he Iigure and _ground were equaL InExperiment 1 and 2_{the 1Oparticipants} compared _the everall _perceptual

lightnes$

between

two rooms. InExperiment _{3 the participants}

comparcd the_perceptual expanse of thefigureand _ground

in

eaeh room,

The

results revealed

the

following:

₍₁₎

The infiuenceof theground on _perceptual

lightness

was stronger than thatof the

figure,

₍₂₎

The

expanse of the total area of theground was _perceived to

be

larger

than that of the

figure

in

pattcrn A,Itwas consistent with thc

known

_phenomenon

that

theground spreads behind

the figure.While the figure was perceived to be largerin _pattcrn

B

and thc _ground

had

less

dominance in

the

appearance of the overall _pattern

lightness.

Key

words: Iightness_perception,figureand

_greund,

_perccptual expansc

Wolff

(1934)

examined the

_perceptual

lightnessof

a figureand ground by using a _pair of _patterned

disks

in

which small ellipses were

dispersed.

_So that

the totatarea of the ellipses was

haif

thearea of the

diskand the relation of

luminance

between the disk

and ellipses was rcversed. The _{participantsperceived} thc

light

gray of thc ellipses on one

disk

to

be

rnuch

lighter

than the light_gray of the second disk,and

that the dark _gray of t,heellipses of thesecond

disk

to

be

much

darkcr

than the dark _gray of the first

disk.

The phenornenon was explained

in

_terms of a stronger centrast effect on the

figure

rather than on

the _ground.

Inthesame _patternhowever, when the

_lightness

of

thewhole _pattern was compared, we noticed thatthe

lighterdisk with _the

dark

ellipse ]ooked lighterthan

the dark

disk

with the lighterellipse even though

the

retinai

luminance

was equal. The _phenomenon

seemed to be contradictory _to

Wolff's

report of a

contrast effect on

the

figure

because

theoverall

per-ceptual lightness of the pattern could

have

been

determined

by thefigure.

Noguchi

& Kozaki

(1985)

showed apositive

contri-bution of the _{ground to}

_lightncss

_{perccption,They}

studied _perccptual

Iightness

by using a

disk

with

*Graduate _{School of Library.}

_Inforrnation

and

dia Studics,

University

of Tsukuba, Kasuga

Tsukuba

305-8550

Me-1-2,

tw{)small squares insideand

found

that

the

insertion

of whitc squares

dccrcased

_{the perceptual lightness}

of the darker _ground, and a lighter_ground also

de-creased tbe apparent lightnessof

b]ack

$quares.

Con-sequently the Gelb effect was observed not only by

the figure

but

also theground.

In the present research we were

interested

in

studying the overal] impression of

lightness

in a

space surrounded by wallpaper

in

which the figure

and _ground

had

stable scission and the same total

area.

Methods

Participants

The1Oparticipantshadnormalvis-ual aeuity wjth or without correction.

Apparatus

and stimulus

We

prepared 2types of wallpaper _patterns

in

which a stable figure-ground scission could

be

clearly observed, Pattern

A

was

composed of

jagged

stripes which are referred toas a

Morinaga _pattern.Pattern B was composed oi many

small squares which were randomly

distributed.

The

rotalarea of the

figure

and _ground were always

equal, Four _pairsof _patterll

A

and

B

cliffered

with a

reversed luminance.

And

4

different

sizelluminance

combinations were _prepared with 2 colors of

blaek,

gray,and white,

[pattern

type

₍₂₎

×

figure-ground

'minance

reversal

{2}

×a luminancelsize combination

(4)]

These 16 wallpaper stirnuli were _printed and a

The Japanese Psychonomic Society

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The JapanesePsychonomic Society

112 The

Japanese

Journa]

of Psychonomic Science Vol,24, No, 1

(a)

(b)

io "o-.op8X

ggs

E.di;ta

o PattemA

l

'

iillllll,ii,

,ll O Lighter-DarkerN Same(C) 20

e･

9

_"NJ

Eio

-tu ) u o PatternB

i-ua-.me,ee

fftewteett,

lo{d)

/g･/s,

= [q tua e E o Figurc when set as

PatternA PetternB PatternA PatternB PatternA PatternB

1.

_{a)

Stimu]us

-,allpapcrs,

(b}

Number of _participants

judged

the room lighter,darker,or the

thc ground was

lighter.

_[c)

Evaluated mean value of _perceptua] ]ightnesswhen

the

other room

1O.

Cct)

Number of participants

judged

thc expanse of

figure

and ground

in

each roem.

samc

was

different_patternwas uscd

in

each of 16small rooms

(W234

mm XH195 mm XD195 mm).

Procedure

The

participants

judged

the overall

perceptual

lightness

of thc space

in

a room

from

a

distance of 30--40cm. The _participants were

in-structed

to

see each room as awhole. InExpenment 1

the participants

judged

thelightnessof 2rooms with

rcvcrscd co[or: a _paircomparison method, In

Experi-ment 2the _partieipantsestimated thc magnitude of

the perceptual lightness of one room against the

other room whjch was rated as

10.

In

Experiment

3

the _participants

_judged

the perceptual expanse oi the

figure

and _ground area ineach room todetermine the

relationship

between

perceptual

lightness

and

per-ceptual area.

Results

and

Discussion

Experiment

1 ln pattern

A,

significantly more

participants

judged

the space to

be

lighter,

with a

higher luuninance _ground than that of a figure

ix2(2)

=

_18,53,

_p<O.Ol).

_The

_{mean number of participants}

for the4pairs are shown

in

Figure

1(b).

Experiment 2 For pattern A and B the rooms

with a higher luminance _ground were _perccived to

besignificantly

lighter

than _the rooms with ahigher

luminance

figure

(pattern

A,

F(1,

3}=35.53.

P"<

O.Ol;

pattern B,F(1,3)T22.42, P<O.05), The mean va]ues

of thefour _pairsof _patternsare shown inFigure 1(c),

Experiment

3

The

perticipants perceived that

in

pattcrn A the expanse of the figurewas significantly

largerthan thatof the _ground

_ixZ

_{(2)-6.94,P<O,05).}

On

the other

hand

the

expanse of the ground

in

patternB appeared to besignificantly

larger

Cx2

(2)=

6,94,P<O.05).The mean numbers of the_participants

forthe 4 _pairsare shc)wn inFigure 1(d}.

Itwas evident

from

the results of

Experiment

1

and 2 that the ground had a greater effect on the

perception of lightness.Consequently the _ground

seemed

to

determine

the

imprcssion

of

the

overa]1

lightnessoC the_pattern.Experjment 3revcaled that

the _perceived area was Largerforthe_ground than for

the

figure

in_pattern

A.

This

result i$con$istent with

the

knewn

interpretation

that a _ground spreads

bc-hind

a

figure.

On

theother

hand,

the area of ground

appeared to be smal]er than that of the figurein

pattern B. This discrepancy may be related tothe

reduction

in

thc

influence

of theground on the

over-all lightnessirnpressioninpattcrn B.

References

Noguchi.

K.,

&

Kozaki,

A.

1985

Perceptual

scission of

surface-lightness and

illurnination:

An

examina-tionof the Gelb effect. Rs),chotogicalResearch,47,

19-25.

Wolff, W, 1934 Induzierte Helligkeitsveranderung.