Effects of whole-body vibration on visual information processing(Summary of Awarded Presentation at the 27th Annual Meeting)

The Japanese Psychonomic Society

NII-Electronic Library Service

The JapanesePsychonomic Society

ThekpanesefournalofPsl)chonomieScience

2009,VoL 28,Ne.1,179-180

Summary

ofAwarded

Presentation2P55

Effects

of

whole-body

vibration

Kazuma

onvisual

information

_processing

IsHiMATsu*,

Nobuyuki

SHiBATA*,

and

Setsuo

iVtitionat

institute

of

OccuPational

Sdety

and

Health,

JllPan*MAEDA*

The

present study

investigated

whether visual

information

_processing

deteriorates

during

exposure towhole-body vibration

(WBV}.

It

focused

on the

frequency

effects of the vibration on

targetcolor discrirninationand target detection _performance. Eight _{participantsperformed} target

color

discrimination

and

target

detection

tasks

with, and without,

5

}Iz

and

16

Hz

sinusoidal

vertical vibration at a rnagnitude of

1.0

ms 2 r.m.s" Their reaction times

(RTs)

as a function of

inter-stimulusintervals

_(ISIs)

between a fixationdisplay and a targetdisplay were compared for

threeexperimental

blocks:

baseline

without vibration

(O

Hz);

5

Hz

vibration; and

16

Hz

vibration.

In

the target

diserimination

tasks the

RTs

during

shorter

ISIs

in

the 5Hz block were significantly

brieferthan during the

O

Hz and 16Hz

blocks.

For

target

detection,

on

the

other

hand,

no

significant differencewas found between _{the three}experimental

blocks,

These

resu]ts suggested

that visual information processing

(i.e.

target color discrimination) could be improved during exposure to5Hz sinusoidal vertical WBV,

Key

words: whole-body vibration. vibration

frequency,

targetcolor discrirnination

Visual information processing isaffected by noise,

vibration, temperature, and other environmental

fac-tors,A few studies have addressed the issueof

whole-body vibration

(WBV)

on visual information

process-ing

(e.g.

Hopcroft & Skinner, 2005;).Although the

general

finding isthat vibration _produces

decre-ments in

_performance,

the stages of inforrnation

processing

affected by WBV are controversial. It

could

be

due

todifferencesof vibration frequency or

magnitude which have been used

in

the _previous

studies. The purpose of thisstudy was to investigate

the effects of WBV on target detection and discrimi-nation. To thisend, performance during exposure to

5 Hz or 16Hz vibration was compared tothat of a

baseline condition without vibration.

Methods

Participants.

Eight

experimentally naive,

right-handed

university students, ranging

in

age

from

21

to

23

years

<,M=21.9

years}were paid partlcipanLs.

All

had

vision which was self-reported as norrnal or

corrected-to-normal, and without color vision

de-fects.

All

_{participantsgave} written inforrnedconsent

beforetaking part inthisstudy, which was approved

by

the appropriate research ethics comrnittees.

*Department _{of Research Planning and}

Coordi-nations, National,Institute

Occupational

Safety

and Health,

Japan,

6--21-1

Tama-ku,

Kawasaki

214-8585

Copyright 2009. The JapanesePsychenomic Society. Allrights reservcd.

NII-Electronic Mbrary

Apparatus.

The

stimuli were presented on a

22-inch color monitor with a resolution of

512

pixels×

512 _pixelsand a frame rate of

100

Hz.

A

color

AV-tachistDscope controlled timing of the events,

gener-ated the stimulL and recorded _the reaction _times

(RTs},

Each _participant was tested in a

dimly

lit

room. The monitor was located at eye level,

approxi-mately 120 cm from the _participant.

A

vibrator was

used to _generate sinusoidal vertical vibration at a

magnitude of 1.0m$-2 r.m.s.

(unweighted

accelera-tion).

StirnulL

For

fixation,

a white central

dot

was

dis-played on a

black

background.

The

target was

dis-played as a central red or green spot

(1.0

deg.

in

diameter).

Proeedure. The participants performed two

types

of

task:

target

color

discrimination

and target detection,

7largetcolor discrimination_tash:

At

the

beginning

of each trialthe fixation

display

was presented

for

l,OOO ms. The fixationdot was then removed.

After

an inter-stimulus interval

CISIs=250,

500, 750, or

1,OOO

rns)a targetdisplay was presented for leO ms,

The _participants were

instructed

torespond tothe

target as. quickly and accurately as possible

by

press-ing

one of twe keys assigned toa color. The RTs and

responses were recorded.

One

experimental block

consisted of 112 trials.Each _{participant performed}

the task during each of the fol]owing three

The Japanese Psychonomic Society

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The JapanesePsychonomic Society

180 The

_Japanese

_Journal

oi Psychonornic Science Vol.28,No. I

vibration

(O

Hz);

a

block

with

5

Hz

vibration; and a

block

with

16

Hz

vibration.

Target

detection

task:

The

triaLprocedures were the

same as those

for

the target color

discrimination

task,with two exceptions.

First,

28

catch tria]s

in

which a target was not presented were included.

Thus, one experimental

block

consisted of 140 trials.

Second,

only one response

key

was used.

Half

of the

participants

started with three

blocks

of the target

color discrirriinationtask,and the Qther ha]fstarted

with three

blocks

of the target

detection

task.

In

each

task,the order of perforrning the

blocks

was

random-ized

among theparticipants.

At

theend of each

block

each participant reported arating of

discomfort

from

the WBV

(from

1,not uncornfortable to 5,very

un-comfortable) as well as a confidence inthe accuracy

of theirresponses

(from

O,cornpletely unconfident to

100,completeLy confident).

Results

and

Discussion

R11s:

All

trials

during

whjch participants

had

made

an

incorrect

response, and alltrials

in

which an

RT

was

]ess

than

100

ms or greater than

2.5

standard

deviations

frorn

the rnean

RT,

were removed

from

the analyses. The

RTs,

as a

function

of experirnental

block and

ISL

are shown

in

Figure

1.

An

ana]ysis of

variance

(ANOVA)

was perforrned on the

RTs

with experimental

block

(O,

5,

16Hz) and

ISI

(250,

500,

750, and

1,OOO

ms) as within-subject variables.

In

the

target color

discrimination

task,a rnain effect of

ISI

and an

interaction

between

experimenta]

block

and

ISI

were significant,

F(3,

2l)

:=

6.66,

P=.O025

_and

FC6,

42)=t 2.40,

p=.0439,

_{respectively.}

The

_{main effect of}

experimental

block

was not significant

(P

=,

.2443).

A

post-hoc

Tukey's

HSD

tcstrevealcd that,inthe 250

ms

ISI,

the

RT

in

the

5

Hz

block

was significantly less

Lhan

during

the

O

Hz and the 16Hz

blocks.

Inthe 500

ms ISL the RT inthe 5Hz block was significantly less

than

that during the OIIzblock.There was no

sig-nificant differenceof RTs

during

the O

Hz

and the

16

Hz

blocks.

Furthermore,

in

the

5

Hz

block

significant

ISI

effects were not observed. Inthe targetdetection

task,the RT$ were not significantly dfferent

for

the

three experimental

blocks.

Discomfort

and co?ijZdence:

Thc

mean ratings of

discomfort and the confidence ratings are listedin

Tablc ]

.

The discomfort was worst

in

the 5

Hz

block,

and leasLinthe OHz block,The confidence ratLng

for

D;scrimination 420A -)Oopg: jso'eS S60iet 340 +OHn beteetion 3203eo2SOrm240 +OHz 320 220 !50 SOO 7S{; 1000 2S] 500 T50 1000 ISI(ms) ISI(ms)

Figure 1. RTs for the target color

tion task

(left)

and

for

the target

detection

task

(righO

Table

1

The

ratings of

discomfort

and confidence.

'

Djscrimination Detection

't.OHz5Hz.T16HzOHz'

'5I･{zl16I'Iz Discomfort1,O{O.4)3"g(1.0)2.3(O.7)i1.0(o.o)3.11i2.1'(O.8)(O.6)

Confidence81,9C16.0)79.5(15.2)82.4i-86.6

(19.0)(20.0)83,8(l7.5)83,1{22,2)

Arote.

Standard

deviations

of the mean are shown

inparentheses.

the three

blocks

was not signjficantly

different,

The

present study revealed that performance of

visual targetcolor discriminationwas improved

dur-ing

the

5

Hz

WBV.

The

rating of worst

discornfort

during

the

5

Hz

bleck

might

be

attributable

for

this

improvement.

One

possible explanatien is

that,

to

maintain an appropriate performance

level

during

the unpleasant 5Hz WBV, an arousal levelor

readi-ness forthe appearance of the target might be

in-creased. Further investigation wil] be required to

demonstrate ifthe 5 Hz WBV itselfhas a _positive

effect on the response selectien stage of visual

infor-mation _processing,

But

contrary to carLier findings,

theprescnt study has suggested thatvisual

Lnforma-tion

processing

(Le.

target color discrimination)

could be improved

during

5Hz sinusoidal vertical

vibration.

References

Hoperoft,

R.,

&

Skinner,

M.

(2005).

C-130J Human

Vibration.

STO-TR-l756.