Disfluency and listeners' attention: An investigation of the immediate and lasting e ects of hesitations in speech
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Date
2009Author
Collard, Philip
Metadata
Abstract
Hesitations in speech marked by pauses, fillers such as er, and prolongations of
words are remarkably common in most spontaneous speech. Experimental evidence
indicates that they affect both the processing of speech and the lasting representation
of the spoken material. One theory as to the mechanisms that underlie these
effects is that filled pauses heighten listeners' attention to upcoming speech. For
example, in the utterance:
(1) She hated the CD, but then she's never liked my taste in er music
The hesitation marked by the filler er would heighten listeners' attention to the
post-dis fluent material (music) which would then be processed and represented
differently to an equivalent stimulus in a passage of fluent speech.
The thesis examines this proposition in the context of an explicit de finition of attention.
The first half of the work investigates whether hesitations heighten two
different aspects of listeners' attention: these are the immediate engagement of
attention to post-dis fluent stimuli at the point they are encountered, and the continued
attention to the representation of stimuli after they are encountered.
In experiment 1, a speech `oddball' paradigm is used to show that event-related
potentials (ERPs) associated with attention (MMN and P3) are affected by a preceding hesitation, indicating an immediate effect of hesitations on listeners overt
attention. Experiments 2 and 3 use behavioural responses and eye-movements measures
during a change-detection paradigm. These experiments show that there is
also an effect on the listeners' attention to the post-dis fluent material after the
initial presentation of the utterance.
The second half of the thesis concerns itself with the timecourse of the attentional
effects. It addresses questions such as: how long-lived is the attentional heightening
and what is the attentional heightening trigger? Experiments 4{7 explore the
relationship between the filler er and periods of silent pause that surround it. Behavioural
(exp. 4{6) and ERP (exp. 7) results show that while extending the period
of silence after the filler er does not affect the immediate engagement of attention,
it will affect subsequent attention to the post-disfluent material: constituents that
are not immediately preceded by the filler er are not attended to in an enhanced
way.
Together, these experiments confirm the proposition that hesitations heighten listeners'
attention to upcoming speech. The thesis outlines the ways in which the
components of this attentional heightening are differentially affected by interaction
between the content and timing of the hesitations encountered. Attention has an
important role to play in the processing of any stimulus. Using disfluency as a test
case, this thesis illuminates its importance in language comprehension.