2-A-05 声質の違いがRepetition Deafnessに及ぼす影響についての検討(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

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The JapanesePsychonomic Society

7heJkePaneseJbumaiofPsychonomieScience

200a,VoL 22,No.1,41-42

Prizewinner's

Summary2-A-05

The

effects

of

vocal

difference

on

repetition

deafness

Masato

NAKAJIMA

and

Tadashi

KiKucHI

Uhiversity

of

71suhuba*

Repetition deafness

(RD)

re[ers to a reduced performance

in

reporting a repeated

item,

compared toa nonrepeated one, during a rapid auditory

presentation,

We

investigated

the effects of avocal

difference

on RD inorder to examine whether an encoding failurewas as a cause of RD. The stirnuli _pronounced

by

a male and a

female

were _presented binaurallyina serial order. The

results showed that RD was obscrved only under

different

voice conditions,

We

_propose an

alternative hypothesis thatan encoding failureisa cause of RD.

Key words: repetition deafness,voca]

difference,

encoding failure,binaural presentation

Introduction

Repetition

deafness

(RD)

rcfers toa reduced

per-formancc

inreporting arepeated itern,compared toa

nonrepeated one,

during

a rapid auditory

presenta-tion,Previous studies

have

suggested a confusion

in

rnemory or an encoding failurecould bethe cause of

RD,

Soto-Faraco

and

Sebastian-Galles

(2001)

ob-served RD using physically mismatched

(different

voices) stimuli with a dichotic_presentation under a

low memory load.They observed thata larger

repe-tition

deafness

was _produced with differentvoice

conditions, rather than with the same voice

condi-tions. Their conc]usion was thatbecause RD could

beobserved foran identical_phoneme, jrrespectiveof

physical

identity.

it

was produced

by

an encoding

failure.However, becau$e theirinvestigationused a

dichotic_presentation thecausc of rcpetition deafness

isstillunclear. A dichoticpresentation,forexample,

could cause some effects on

RD

such as a spatial

attentional shift or cause some

form

of perceptual

limitation

_(e.g.,

_precedence effecO. Physical

mis-matching could also cause a _precessing load

to

,

cmmlnate two volces,

Inthe prcscnt cxpcriment, we investigatedan

en-coding failurehypothesis as explanation of thecause

of RD,

Specifically,

we focused on the effects on

repetition

deafness

of a vocal

difference

by

using stimuli _presented

in

a serial

binaural

manner.

*

_Institute

_of

_Psychology,

_University

_{of Tsukuba,}

1--1-1Tennoudai, Tsukuba, Ibaraki

305-8572

Method

Participants

Twcnty

graduate and

under-graduate students _participated

in

the experiment.

The data from two _participantswith high error rates

were excluded

from

the

analyses.

Materials and design Three

CV

syllables

Upaf,

/piL

and

fpo/)

were _pronounced

by

a male and a

female

and

digitally

recorded at 44.1kHz. Each of

the stimuli was also compressed by up te1OO milli-seconds without any alteratien of the original _pitch

quality,

We

constructed

lists

of stimuli

(lists

of

two

and

three elements)

by

combining two or three of the

compressed syllables

in

300

milliseconds,

The

lists contained

two

successive syllables as critical

ele-ments

(CE).

The listsof two elements consisted of

the

CE

followed

by

1OO

milliseconds of silence. The

lists

of threeelements consisted of the

CE

_preceded,

or followed,byanother syllab]e, The study involved

two main

factors:

voice

(thc

same, or a different

voice); and repetition

_{repeated

or unrepeated). Inthe

same voice condition the _quality of the voices was matched, whereas the voice quality was mismatched

in

the

different

voice condition. The repeated

condi-tionconsisted of two syllables which were thesame

as the CE, Intheunrepeated condition another

sylla-ble

was used forthe second CE of a repeated list,

Procedure

Thestirnuliwerepresentedbinaurally

through headphones attached to a _personal

com-putcr,The participantswere asked torecall all of the

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_Japanese

_Jeurnal

of Psychonomic

Science

VoL

22,

No.

1

Mistakes inthe order were permitted. The

partici-pants were also required to recall repeated elements

as many times as they were heard.

Each tria]began with a warning tone with a

fre-quency of

500

Hz

and a

duration

of

500

milliseconds.

Then,

after

500

milliseconds of silence, the

300-millisecond

list

was _presented. Presentation of

the

list

was

followed

by a masking noise for1OO

millisec-onds. The _participantsused the computer

keyboard

to

indicate

theirresponses.

Results

We

counted a response as correct

if

the

first

and

second

CEs

were reported correctly. The mean

percentage of CE recall ineach condition isshown in

Figure 1. An analysis of variance was calculated

with within-participant

factors

of voice

(the

same vs,

differenO

and repetition

(repeated

vs. unrepeated>

from

data using thelistsof two and thrqeelements. The analyses

indicated

that

an

interaction

between

voice and repetition was significant for the two-element list,F(1,17)=:.'12.39,P<

.Ol

_ancl forthe three-element list,F(1,17>=48.75,P<.O1.

The

simple rnain effect of repetition and a

different

voice was

significant

for

the two-element

list,

F{1,17)=11.82,

P<.Ol

and forthc three-element list,F(1,17)=72.02,

DRepeated

-Unrepeated

1OOAS

80i8di

602oo

40vtg

2otsi

o

Same

DMerent

Same

DMerent

2

Elements

3

Ele-ents

Figure

1,

The

mean _percentage of

CE

recall

in

repeated

_(empty

bar) and unrepeated

_(fi11ed

bar)

lists.

p<.Ol.

But the effect of repctition and the same

voice was not significant

for

either of the lists.

Discussion

The

results of the present experiment

demen-strated that RD was observed only under different

voice conditions and

irrespective

of whether a

two-er three-element

list

was used. This

finding

sug-gested

that

different

veices would cause RD.

Repeti-tion deafness forthe same voice was not observed,

unlike the study of Soto-Faraco & Sebastian-Galles

(2001),

The

RD

observed

in

theirexperiment,

there-fore,may have been caused by some perceptual

limi-tation which was _produced by a dichotic

presenta-tion.

This explanation would

be

able toaccount

for

thelargerRD oi the

_physical

misrnatch obtained in

theirstudy

(Soto-Faraco

& Sebastian-Galles,2001).

From the present results, we propose an

alterna-tive hypothesis of encoding

failure

as the cause of

RD.

An

encoding

failure

could

be

explained

by

the refractory period, inwhich thesensitivity toa

repeti-tion

of an

itern

is

reduced

by

the recognitien unit

after being activated by a preceding identical

stimu-lus,

Our

hypothesis

suggests that the refractory

period would be_produced

by

discriminating

the

qua-lityof _the voice. After a specific vocal phoneme

is

encoded and activates arepresentation, the

represen-tation ¢ould accept an

identical

_phoneme but could not accept aphysically mismatched one

during

acti-vation

in

the refractory period.

Thus

an encoding

failure

would be caused by a physical mismatch.

Different

_phonemes,

however, would

be

encoded

by

differentrecognition units so that encoding would

not

fail.

The

correct recognition of _physically

mis-matched ancl repeated items would therefore be

re-duced and RD would occur,

References

Soto-Faraco,

S. & Sebastian-Galles,N. 2001 The

effects of acoustic mismatch and selective listening

on repetition deafness,

lburnal

of

Experimentat

Rsychotog:y:

Hiiman

RircePtion

&

Peizfbrmance,

27,

356-369.