The influence of visual perception for hands on spatial attention of peripersonal space(Summaries of Awarded Presentation at the 28th Annual Meeting)

The Japanese Psychonomic Society

NII-Electronic Library Service The JapanesePsychonomic Society

ThelopaneseJbumotofRs'ychonomicScience

2elO,VoL 29,No.I,75-76

Summary

ofAwarded

Presentation5-212

The

on

influence

of

visual

spatial

attention

of

Reiko

ENoMoTo

Senshu

perception

for

hands

peripersonal

space

and

Seiji

Uhiversit),*YAMAGAMI

Since

human

hands

frequently

interact

with external objects,

it

is

important

to

detect

events

that

will occur near thehands as

fast

as _possible.

Previous

studies

have

suggested thatthe visual

detection

of a targetnear a hand is

facilitated

relative todetectiondistantfrom thehancl

(Reecl

et

aL, 2006). However, theirinvestigations have

focused

on the palrn,because

it

is

normally the

contact surface of

the

hand. Our study investigated whether a facilitated

detection

would occur

with the

back

of the

hand.

that

has

little

interaction

with objects, when itwas facing towards

targets.The results shewed a different

_pattern

between the

_palrn

of the

hand

and the

back.

In

addition, thispattern appears tobe related to the function of the back of the hand.

These

results

have

suggested that the

functional

characteristics of thesurfaces of

the

hand

affect detectionof

targets

near the hand differently.

Key

words:

hand

perception, spatial attention, _peripersonalspace

It

has

been

recently suggested thatthe space near

the body

(peripersonal

space) isrepresented

cliffe-rently

frorn

other regions of space, Reed etal,

(2006)

asked _participants to visually

detect

a target pre-sented on a monitor, while _placing the _{participants'}

hand

near

it.

Their

results

demonstrated

that

partici-pants detect targets near the hand fasterthan the

targetswhich were

distant

from

the

hand,

They

also

observed that the effect was apparent when either

proprioceptiveor visual inferrnationabout the hand

could

be

used. These results

have

been

supported

by

the reports of visual-tactile bimodal neurons that

detect

events near the

hand,

so thatappropriate

ac-tion fora desirableor threatening targetcould be

taken.

From

thisevidence,

it

is

assumed that thc

functional eharacteristics of body parts strongly

affect spatial attention in_peripersonal space.

For

humans,

the palm of

the

hand

often

interacts

with objects whereas the

back

has

fcw

functions

when we use our hands. In thisstudy, we used the

covert orienting _paradigm of Reed et al. C2006} to

investigate

whether

functional

differencesbetween

the palm and

back

of the

hand

have

cliffcrent

infl-*Departrnent _{of Psychology, Graduate School of}

Humanities,

Senshu

University

2-1-1,

Higashi-mita

Tama-ku,

Kawasaki,

Kanagawa

214-O032

e-mail:[email protected]

Copyright 201O,Thc JapanesePsychonomic Society.Allrights reserved. uences on spatial attention near it.

Method

Participants.

Eighteen

right-handed students

par-ticipated intheexperirnent.

Apparatus

and stimuli. The stimuli consisted of a

fixationpoint

(2D

×2e)and two rectangles

_{20

×

1.70).

Each

was at a

distance

of 50from the fixation_point.

In the experiment, two wooden

hands

(a

left

and

right hand) with rubber _gloves were used as

fake

hands.

They

were

fixed

by

a

tripod

stand on the

table.The _participantswore thesame type of

_gloves

during

the

experiment to decrease the visual

diffe-rences between the

fake

and real

hands.

This

experi-ment was conducted using PsyScope X46, and the stimuli were presented on a

17-inch

CRT

moniter, A

Button Box was used as a response

device.

Procedure. Each participantsat

in

a chair

in

front

of the monitor, with their head fixedby a chinrest.

One

of the

fake

hands

was _placed near the outside of

a targetpositionand on the sarne side

(Le,

a

fake

left

hand was _placenear thetargeton the]eftside), with

its

fingertips

touching

the monitor. Inthe_palm

con-dition,

the palm side facedthe target and inthe back condition, theback of the

hand

faced

the target,

The participants were presented with a central

cross, flankedby two empty rectangles located50 to

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76

The

Japanese

Journal

of

Psych

either sidc of

it

and they were

instructed

to

fixate

on the cross. Between 1,500ms and 3,OeO ms after the

beginning

of the

triaL

the

border

of one of

the

_two

rectangles darkened, cueing attentien to that

loca-tion,The target appcared

200

ms later,For valid

trials,the targetappeared inthe cued square. For

invalid trials,the targetappeared in the square on

the oppositc side of the

fixation

cross.

In

addition, tbere were catch trialsinwhich one square was cued

but

ne

target

appeared.

The

participantswcre asked

toindicatethe _presence of a targetby pressing the

button

as _quickly and accurately as _possible.The

experiment consisted of

four

conditions:

(a)

fake

left

hand back side towards target;

(b)

fake lefthand

palm side;

(c)

fake

right

hand

back

side;and

(d)

fake

right hand _palm sicle,Ineach condition, a

participant

responded

by

using their

hand

thatwas contralateral

to the fake hand and the participanVs

ipsilatcral

hand was _placed on their thigh.These conditions

were

brocked

and the order was counterbalanced,

Within

each condition of thisexperimcnt, 70% of the

trials

were va]id cued

tria]s,

2096 wcre

invalid

cued

trials,and 10% were catch trials.

Design. The experimental design included four

factors:

Cue

validity (vaLid,invalid};

Hand

orientation

(palm,

back);Hand side

(left,

right); and Target side

Cleft,right).

Results

and

Discussion

Figure

1

displays

the results

in

each condition.

A

four-way repeated measures ANOVA was carried out

on the mean

RTs.

The ana]ysis revealed a main effect of

Cue

validity

(F(1,17)=36.30,

P<,Ol)

and

Target

side

(F(1,17)=12.34,

_P<.O!).

Although

interactions

between Cue validity ×Targct side, Hand side ×

Tar-get side, and

Cue

validity XHand side×

Target

side were allsignificant

_(F{1,17)

'=

22.72,

P<

.O1;

F(1,17}=-. 10.01,

_p<.Ol;

F(1,17)=-'9.96,p<.Ol, respectively.),

they were rnediated by

the

four-way interaction

(F

(1,17}=7,96,

p<

.05}.

In_general,the facilitationeffect

as reported

by

Recd et al.

(2006)

was not found

in

both side conditiens. However, this

four-way

interac-tion indicateddifferent_{performance patterns}forthc

palm and the

back

of the

hand,

Post

hoc

analysis

revealed that

in

the

invalid

trialsthe targets that

onomtc

6Ev-cr

4o4

Sciencc

Vol,

_29,

_No.

1

4aE--C3 VALID INVALIO

ORIENTATION=PALM

SIDE

4 3 IT-teftMT-right T-leftT-right H-laft H-right VALID INVALID

ORIENTATION=BACK

SIDE

Figure

1,

The

mean

RT

in

the palm condition

'

(Upper)

and in the back condition

(Lower).

Error

bars

are

SEs.

"H"

and "T"

mean "Hand"

and 'tTarget",

rcspectively.

appeared

in

the

left

side were

detected

faster

when

the

fake

hand was _ptaced at thc right side and its

back faced

to

the

targets

(P

<

,05}.

Inthiscase,

the

cue appeared on theright side near theright

fake

hand, and soon after thetargetappeared on the leftside, It seemed like]ythatthc perceptionof this

by

the

par-ticipantswas that the targethad moved frornnear

the right hand tothe

left

side.

We

use mainly the

back of our hands tomove objects near thc hand to

distant

space.

So,

it

is

_possiblethat

the

visual

pres-ence ofthe back ofthe hand was

linked

toan

implicit

movement of targetsin invalidtrials,and therefore

ledto

facilitated

detection

inthatcondition.

These

findings

suggest a link between the

func-tionalcharacteristics of the hand and particular

tar-get propertiesrelated to itcan change the

distribu-tionof attention near peripersonalspace,

That

is,

if

the targetisperceived as a consequence, or a cause,

of hand _posture, itis_possible that detection of a

targetnear the hand would bemore

facilitated,

References

Reed,C.L.

Grubb,

J.

D.,&

Steele,

C.

_(2006).

IIandsUp:

Attcntional propritization of space near the hand.

fournal

of

Experimental Psychotogy:lluman