Everyday speech is littered with disfluencies such as filled pauses, silent pauses, repetitions and repairs which reflect a speaker’s language production difficulties. But what are the effects on language comprehension? This thesis took a novel approach to the study of disfluencies by combining an investigation of the immediate effects on language processing with an investigation of the longer-term effects for the representation of language in memory. A series of experiments is reported which reflects the first attempt at a systematic investigation of the effects of different types of disfluencies on language comprehension. The experiments focused on the effects of three types of disfluencies—ers, silent pauses, and repetitions—on the comprehension of subsequent words. Critical words were either straightforward continuations of the pre-interrupted speech or a repair word which corrected the pre-interrupted speech. In addition, the effects that occur when er, repetition, and repair disfluencies themselves are processed, were assessed. ERPs showed that the N400 effect elicited in response to contextually unpredictable compared to predictable words was attenuated by the presence of a pre-target er reflecting a reduction in the standard difference where unpredictable words are more difficult to integrate into their contexts. This finding suggests that ers may reduce the extent to which listeners make predictions about upcoming words. In addition, words preceded by an er were more likely to be correctly recognised in a subsequent memory test. These findings demonstrate a longer-term consequence for representation which may reflect heightened attention during processing. Silent pauses did not affect the N400 but there was some indication of an effect on recognition memory. Repetition disfluencies did not affect the N400 or recognition memory. These findings demonstrate the importance of the nature of the disruption to speech. For all types of disfluent utterances, unpredictable words elicited a Late Positive Complex (LPC), possibly reflecting processes associated with memory retrieval and control as listeners attempted to resume structural fluency after any interruption. Ers themselves elicited standard attention-related ERP effects: the Mismatch Negativity (MMN) and P300 effects, supporting the possibility that ers heighten attention. Repetition disfluencies elicited a right posterior positivity, reflecting detection of the disfluency and possibly syntactic reanalysis. Repair disfluencies elicited an early frontal negativity, possibly related to the detection of a word category violation, and a P600 effect, reflecting syntactic reanalysis. The presence of an er preceding the repair eliminated the early negativity, but had no effect on the P600 suggesting that ers may prepare listeners for the possibility of an upcoming repair, but that they do not reduce the difficulty associated with reanalysis. Taken together, the results from the studies reported in the thesis support an account of disfluency processing which incorporates both prediction and attention.

Thesis (Ph. D.)--University of New South Wales, 2003. / Also available online.

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This thesis is in two parts. Part 1 reviews work on comprehension of grammatical structure in children and describes the development of a new Test for the Reception of Grammar (TRCG). TROG assesses understanding of a variety of grammatical contrasts using a format where the child is required to select from an array a picture to correspond to a phrase or sentence spoken by the tester. Results from 280 normal children aged from 3—6 to 13-2 are presented. It is shown that several grammatical structures are not completely mastered by age 13. and in some instances it appears that the accepted rule that comprehension precedes production is contravened. Data on reliability and validity of TROG are also presented. Part 2 is Concerned with the application of TROG to 73 children with receptive and expressive developmental language disorders. It is shown that the majority of these children perform below age level both on TROG and on a test of receptive vocabulary. Further. there is a strong relationship between performance on TROG and grammatical complexity of expressive speech. Structures involving decoding of .word order appear to give these children particular difficulty, over and above their general comprehension deficits. Results are discussed in relation to psychological theories of developmental language disorders, and implications for the classification of these disorders are considered.

Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 186-188).

Psycholinguistic evidence suggests that people predict upcoming words during language comprehension. While many studies have addressed what information people predict, less is known about the role of factors that potentially mediate predictive processing. This thesis examines predictions of semantic information and word form information. It investigates whether predictive processing is mediated by availability of cognitive resources and time to generate predictions, and compares predictive processing in native (L1) speakers and non-native (L2) speakers. This thesis presents two major lines of work. Two eye-tracking studies investigate prediction of semantic and word form information using a visual world paradigm. In further two ERP studies, we address the interplay of semantic and word form information in a paradigm which combines both possibilities. Experiments 1 and 2 were an eye-tracking study conducted on L1 and L2 speakers of English. The study has demonstrated that L1 and L2 speakers predict semantic information, but their predictive eye movements are delayed when they are under a cognitive load. The effects of cognitive load on predictive eye movements suggest a role of cognitive resources in language prediction in both L1 and L2 speakers. Experiments 3 and 4 were another eye-tracking study conducted on L1 and L2 speakers. The study has shown that L1 speakers predict word form information, but L2 speakers do not. Experiments 5 and 6 were an ERP study, which investigated the interplay of prediction of semantic and word form information in L1 English speakers. Consistent with the two sets of eye-tracking experiments, L1 speakers predicted both semantic and word form information, but word form was only predicted when sentences were presented at a slower rate, while semantic information was predicted at standard and slow presentation rates. Experiments 7 and 8 used the same method as Experiments 5 and 6, conducted on L2 English speakers. L2 speakers comprehended sentences incrementally, but there was no clear evidence that they predicted semantic information or word form information. Experiments 5 – 8 suggest that prediction of word form information is mediated both by nativeness of the target language and by reading rates. To conclude, both L1 and L2 speakers make predictions, but prediction of semantic information occurs only when there are enough cognitive resources available. Prediction of word form can occur in L1 speakers, but it occurs only when there is enough time available. There is no evidence that L2 speakers predict word form, suggesting a role of nativeness of the target language. The findings are consistent with the production-based prediction model of language prediction, in that prediction of word form is less likely to occur compared to prediction of semantic information. Furthermore, the findings are also consistent with the claim that not everyone makes predictions, and predictions do not always occur. The thesis concludes that prediction is additional processing for the comprehension system, and is not always implicated in the comprehension system.

Competing speech seems to pose a greater challenge to spoken language comprehension than does competing noise, especially for older adults. The difficulties of older adults may be due to declines in auditory and cognitive processing. However, evidence suggests that the use of top-down information processing to overcome this interference may be preserved in aging. This research investigated the effect of speech- and noise masking on language comprehension, as well as age-related differences in the use of top-down processing to overcome masking. Topic I examined whether younger and older adults gain the same release from masking given a partial preview of a target sentence in quiet (auditory prime) prior to hearing the full sentence in noise, and investigated the auditory factors contributing to the advantage provided by the primes. Results showed that despite age-related declines in overall performance, younger and older listeners benefited similarly from priming. This benefit was not attributable to cues about the target talker’s voice or fluctuations in the amplitude envelope of the target sentences. Topics II and III examined the effect of speech- and noise masking on the time-course of stream segregation. The analyses revealed that stream segregation takes time to build up when a speech target is masked by other speech, but not when it is masked by noise. Subsequent analyses showed that in younger adults, the delay in segregation under speech masking was primarily due to the vocal similarities between the talkers, with interference from the semantic content of the masker playing a secondary role in impeding performance. The results also showed that older listeners were less efficient than younger listeners in segregating speech from speech-like maskers. Furthermore, older listeners benefited less than younger listeners when the amplitude envelope modulations of maskers were limited. Overall, the findings indicate that some of the language comprehension difficulties experienced by older listeners in noisy environments may be due to age-related declines in stream segregation and a decreased ability to benefit from fluctuations in the amplitude envelopes of maskers. However, benefit from priming may help offset some of these age-related declines in auditory scene analysis.

Competing speech seems to pose a greater challenge to spoken language comprehension than does competing noise, especially for older adults. The difficulties of older adults may be due to declines in auditory and cognitive processing. However, evidence suggests that the use of top-down information processing to overcome this interference may be preserved in aging. This research investigated the effect of speech- and noise masking on language comprehension, as well as age-related differences in the use of top-down processing to overcome masking. Topic I examined whether younger and older adults gain the same release from masking given a partial preview of a target sentence in quiet (auditory prime) prior to hearing the full sentence in noise, and investigated the auditory factors contributing to the advantage provided by the primes. Results showed that despite age-related declines in overall performance, younger and older listeners benefited similarly from priming. This benefit was not attributable to cues about the target talker’s voice or fluctuations in the amplitude envelope of the target sentences. Topics II and III examined the effect of speech- and noise masking on the time-course of stream segregation. The analyses revealed that stream segregation takes time to build up when a speech target is masked by other speech, but not when it is masked by noise. Subsequent analyses showed that in younger adults, the delay in segregation under speech masking was primarily due to the vocal similarities between the talkers, with interference from the semantic content of the masker playing a secondary role in impeding performance. The results also showed that older listeners were less efficient than younger listeners in segregating speech from speech-like maskers. Furthermore, older listeners benefited less than younger listeners when the amplitude envelope modulations of maskers were limited. Overall, the findings indicate that some of the language comprehension difficulties experienced by older listeners in noisy environments may be due to age-related declines in stream segregation and a decreased ability to benefit from fluctuations in the amplitude envelopes of maskers. However, benefit from priming may help offset some of these age-related declines in auditory scene analysis.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1971. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

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