Perception of accents and dialects in adults and infants

247 Pages·2010·1.19 MB·English

This copy of the thesis has been supplied on condition that anyone who consults it is
understood to recognise that its copyright rests with its author and that no quotation
from the thesis and no information derived from it may be published without the
author’s prior consent.
PERCEPTION OF ACCENTS AND DIALECTS IN ADULTS AND INFANTS

by

JOSEPH PATRICK BUTLER

A thesis submitted to the University of Plymouth
in partial fulfilment for the degree of

DOCTOR OF PHILOSOPHY

School of Psychology
Faculty of Science

October 2009
Joseph Patrick Butler
Perception of accents and dialects in adults and infants
Abstract
This thesis has been undertaken with the purpose of investigating how adult speech
processing systems are affected by, and how they cope with, the presence of different
regional and foreign accents in speech, and to investigate the developmental origins of
adult accent perception capabilities.

Experiments 1 to 4 were designed to investigate the long term effects of exposure to
different accents, and whether short term adaptation to an accent was possible, using
a lexical decision task. The results demonstrated an effect of accent familiarity but no
short term adaptation was evident. Experiments 5 to 7 investigated the short term
effects of accents by looking at the length of activation of accent-related information in
working memory by using a cross-modal matching task. The results found that
selective accent related effects were reduced after a 1500 millisecond delay.

Experiments 8 to 11 investigated infants’ discrimination abilities for regional and
foreign accents using a preferential looking habituation method, and found infants at 5
and 7 months could discriminate their own accent from another, unfamiliar regional
accent, but could not discriminate two unfamiliar regional accents at 5 months or a
foreign accent from their own at 7 months. Experiments 12 and 13 investigated how
accents affected infants’ word segmentation abilities with continuous speech at 10
months, and found that segmentation was impaired in the presence of regional and
foreign accents.

Using these results, the Accent Training Model (ATP) is proposed, which attempts to
explain how accent related indexical information is processed in the speech processing
system. The findings of the infant studies further our understanding of the effect of
indexical variation in early speech perception.
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Table of Contents
Abstract - ii
List of figures - vii
List of tables - x
Acknowledgments - xi
Author’s declaration - xii

Introduction - 1

Chapter 1: Literature review of adult accent perception - 6
Models of lexical processing in adults - 6
Processing of speech variability in models of lexical access - 11
Data on accent perception in adults - 18
The effect of accent on intelligibility and comprehensibility - 19
Evidence for adaptation - 22
Evidence against adaptation - 25

Chapter 2: Short term and long term adaptation to accents - 30
Adult Experiment 1: Effect of accent familiarity in the short
and long term - 30
Methods - 31
Results - 36
Discussion - 49
Adult Experiment 2: Short term accent adaptation through exposure to
spontaneous speech - 51
Methods - 52
Results - 53
Discussion - 61

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Adult Experiment 3: Effect of instructions on short term
adaptation - 61
Methods - 62
Results - 62
Discussion - 71
Adult Experiment 4: Generalisation of effect of accent familiarity - 72
Methods - 73
Results - 74
Discussion - 79
General discussion Adult Experiments 1 to 4 - 80

Chapter 3: Accent processing in working memory - 83
Adult Experiment 5: Representations of accent related
information in short term memory - 83
Methods - 84
Results - 86
Discussion - 91
Adult Experiment 6: Generalising accent related representations
in short term memory - 92
Methods - 92
Results - 93
Discussion - 97
Adult Experiment 7: Accent related information in non-words - 97
Methods - 98
Results - 99
Discussion - 104

Chapter 4: General discussion of adult studies - 105

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Chapter 5: Literature review of developmental accent perception - 118
Early phonological development - 118
Processing indexical information in childhood - 121
Early language perception - 126
Early accent perception - 130
Accents and word segmentation - 135

Chapter 6: Accent discrimination in infancy - 141
Infant Experiment 8: Early native accent discrimination at
five months - 141
Methods - 141
Results - 145
Discussion - 146
Infant Experiment 9: Early regional accent discrimination at
five months - 148
Methods - 149
Results - 150
Discussion - 152
Infant Experiment 10: Development of native accent
discrimination at seven months - 154
Methods - 155
Results - 155
Discussion - 156
Infant Experiment 11: Regional versus foreign accent
discrimination at seven months - 158
Methods - 158
Results - 160
Discussion - 161
General discussion Infant Experiments 8 to 11 - 163
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Chapter 7: Word segmentation in continuous accented speech - 166
Infant Experiment 12: Regional accents and word segmentation
at 10 months - 166
Methods - 167
Results - 170
Discussion - 172
Infant Experiment 13: Foreign accents and word segmentation
at 10 months - 173
Methods - 174
Results - 175
Discussion - 178

Chapter 8: Discussion of developmental studies - 179

Chapter 9: General discussion - 189

References - 197
Appendix A: Experiments 1 to 7 stimuli - 211
Appendix B: Experiments 8 to 13 stimuli - 227
Appendix C: Experiments 1 to 7 speakers - 230
Appendix D: Experiments 8 to 13 speakers - 232

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List of figures
Figure 1: What blocks of sentences participants heard in week one and week two,
broken down between conditions – pg 34
Figure 2: Mean reaction times between experimental blocks in week 1 of exp 1,
broken down between groups – pg 37
Figure 3: Average looking times for the two experimental blocks, broken down
between groups and speakers – pg 39
Figure 4: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups – pg 40
Figure 5: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups and speakers
– pg 42
Figure 6: Mean RT’s between experimental blocks in week two, broken down into
groups – pg 44
Figure 7: Average reaction times to the baseline blocks between weeks one and
two, broken down between conditions – pg 46
Figure 8: Average reaction times to the foreign accent block in week one and the
same foreign accent block in week two, broken down between conditions
– pg 47
Figure 9: Average reaction times to the foreign accent block in week one and
different foreign accent block in week two, broken down between
conditions – pg 48
Figure 10: Mean RT’s between experiment blocks, broken down into groups
– pg 55
Figure 11: Mean reaction times for each experimental condition, broken down
between speakers – pg 56
Figure 12: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups – pg 57
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Figure 13: Mean RTs between experimental blocks between Experiments 1 and 2,
broken down into groups – pg 59
Figure 14: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups and experiments
– pg 60
Figure 15: Mean RT’s between experimental blocks, broken down into groups
– pg 64
Figure 16: Mean reaction times for each experimental condition, broken down
between speakers – pg 65
Figure 17: Mean reaction times to the first and last three sentences heard in each
experimental condition, broken down into groups – pg 66
Figure 18: Mean RTs between experimental blocks between Experiments 1 and 3,
broken down into groups – pg 67
Figure 19: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups and experiments
– pg 68
Figure 20: Mean RTs between experimental blocks between Experiments 1 and 3,
broken down into groups – pg 69
Figure 21: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups and experiments
– pg 71
Figure 22: Mean reaction times (RT) between experimental blocks, broken down
into groups – pg 76
Figure 23: Mean reaction times for each experimental condition, broken down
between speakers – pg 77
Figure 24: Mean reaction times to the first and last three sentences heard within
each experimental block, broken down into groups – pg 78
Figure 25: Mean RTs for each experimental blocks, broken down into conditions
– pg 87
viii
Figure 26: Mean RT’s for each speaker, broken down into
conditions – pg 90
Figure 27: Mean RT’s for each experimental blocks, broken down into conditions
– pg 94
Figure 28: Mean RT’s for each speaker, broken down into
conditions – pg 96
Figure 29: Mean RT’s for each experimental blocks, broken down into conditions
– pg 101
Figure 30: Mean RT’s for each speaker, broken down into
conditions – pg 103
Figure 31: Accent Training Procedure (ATP) Model of how accent related indexical
information in processed in the speech processing system
– pg 114
Figure 32: Mean looking times to the habituated and new accent, broken down
between conditions – pg 146
Figure 33: Mean looking times to the habituated and new accent, broken down
between conditions – pg 151
Figure 34: Mean looking times to the habituated and new accent, broken down
between conditions – pg 156
Figure 35: Mean looking times to the habituated and new accent, broken down
between conditions – pg 160
Figure 36: Average looking times to the target and new word lists, broken down
between conditions – pg 170
Figure 37: Average looking times to the target and new word lists, broken down
between conditions – pg 176

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