The Processing of Accented Speech

This thesis examines the processing of accented speech in both infants and adults. Accents provide a natural and reasonably consistent form of inter-speaker variation in the speech signal, but it is not yet clear exactly what processes are used to normalise this form of variation, or when and how those processes develop. Two adult studies use ERP data to examine differences between the online processing of regional- and foreign-accented speech as compared to a baseline consisting of the listeners’ home accent. These studies demonstrate that the two types of accents recruit normalisation processes which are qualitatively, and not just quantitatively, different. This provided support for the hypothesis that foreign and regional accents require different mechanisms to normalise accent-based variation (Adank et al., 2009, Floccia et al., 2009), rather than for the hypothesis that different types of accents are normalised according to their perceptual distance from the listener’s own accent (Clarke & Garrett, 2004). They also provide support for the Abstract entry approach to lexical storage of variant forms, which suggests that variant forms undergo a process of prelexical normalisation, allowing access to a canonical lexical entry (Pallier et al., 2001), rather than for the Exemplar-based approach, which suggests that variant word-forms are individually represented in the lexicon (Johnson, 1997). Two further studies examined how infants segment words from continuous speech when presented with accented speakers. The first of these includes a set of behavioural experiments, which highlight some methodological issues in the existing literature and offer some potential explanations for conflicting evidence about the age at which infants are able to segment speech. The second uses ERP data to investigate segmentation within and across accents, and provides neurophysiological evidence that 11-month-olds are able to distinguish newly-segmented words at the auditory level even within a foreign accent, or across accents, but that they are more able to treat new word-forms as word-like in a familiar accent than a foreign accent

Working Memory and Second‐Language Accent Acquisition

We explored the proposal that overt repetition of verbal information improves the acquisition of a native accent in a second language. Mandarin-speaking Chinese learners of English were recorded while repeating and reading out English sentences before and after one of three treatments: (1) Repeating native English sentences subvocally, "covert repetition,"(2) Repeating sentences out loud, "overt repetition," and(3) Unfilled time of comparable duration. The sentences were rated by English speakers for their nativeness, fluency, and intelligibility. Overt repetition improved accent rating for read-out sentences. Covert repetition did not. Neither condition improved accent rating for repeated sentences, suggesting that immediate repetition depends on temporary rather than long-term representations. Our results provide some support for the use of overt repetition in accent learning. From a theoretical perspective, an interpretation is proposed in terms of a separation between phonological and articulatory coding within the phonological loop component of working memory

Working memory in simultaneous interpreters: Effects of task and age

This study examines whether interpreters have better working memory (WM) than noninterpreters, taking into account different WM components and the potential modulatory influence of age. Younger and older interpreters and non-interpreters were tested on reading span, nonword repetition, and order- and category-cued recall, using English, second-language materials. Articulation rate was also assessed. Interpreters outperformed non-interpreters in reading span and nonword repetition, but not cued recall and articulation rate. These results suggest that interpreters have better ability to manipulate information in working memory and process or store sub-lexical phonological representations, but have no advantage in short-term retention of words and their meaning. Compared to the other tested groups, younger interpreters were marginally better in nonword repetition and cued recall, suggesting that future studies on WM advantages in interpreters should consider the age factor

Age differences in encoding-related alpha power reflect sentence comprehension difficulties

When sentence processing taxes verbal working memory, comprehension difficulties arise. This is specifically the case when processing resources decline with advancing adult age. Such decline likely affects the encoding of sentences into working memory, which constitutes the basis for successful comprehension. To assess age differences in encoding-related electrophysiological activity, we recorded the electroencephalogram from three age groups (24, 43, and 65 years). Using an auditory sentence comprehension task, age differences in encoding-related oscillatory power were examined with respect to the accuracy of the given response. That is, the difference in oscillatory power between correctly and incorrectly encoded sentences, yielding subsequent memory effects (SME), was compared across age groups. Across age groups, we observed an age-related SME inversion in the alpha band from a power decrease in younger adults to a power increase in older adults. We suggest that this SME inversion underlies age-related comprehension difficulties. With alpha being commonly linked to inhibitory processes, this shift may reflect a change in the cortical inhibition–disinhibition balance. A cortical disinhibition may imply enriched sentence encoding in younger adults. In contrast, resource limitations in older adults may necessitate an increase in cortical inhibition during sentence encoding to avoid an information overload. Overall, our findings tentatively suggest that age-related comprehension difficulties are associated with alterations to the electrophysiological dynamics subserving general higher cognitive functions

Semantic Processing in Children with Reading Comprehension Deficits

This investigation compared the semantic processing abilities of fourth-grade children with specific reading comprehension deficit (SRCD) to a chronological-age matched control group (4NR) and a younger, reading comprehension matched control group (2NR) on a single word shadowing task. During this experimental task, the children were expected to listen to a sentence and repeat the final word (cued by a change in speaker voice) of the sentence as fast and as accurately as possible. There were two experimental conditions: 1) a high cloze probability sentence condition in which the final word of the sentence or target word was semantically related to the sentence prime and 2) a low cloze probability sentence condition in which the target word was semantically anomalous to the sentence prime. All three groups of children displayed higher contextual effects in the high cloze probability condition compared to the low cloze probability condition. However, children with SRCD did not perform significantly different than controls in either experimental condition. These findings provide evidence of contextual enhancement within the single-word shadowing task, even for children with SRCD, and are discussed within the context of a semantic processing deficit theory in children with SRCD

Semantic radical consistency and character transparency effects in Chinese: an ERP study

BACKGROUND: This event-related potential (ERP) study aims to investigate the representation and temporal dynamics of Chinese orthography-to-semantics mappings by simultaneously manipulating character transparency and semantic radical consistency. Character components, referred to as radicals, make up the building blocks used dur...postprin

Are simultaneous interpreters expert bilinguals, unique bilinguals, or both?

Simultaneous interpretation is a cognitively demanding process that requires a high level of language management. Previous studies on bilinguals have suggested that extensive practice managing two languages leads to enhancements in cognitive control. Thus, interpreters may be expected to show benefits beyond those seen in bilinguals, either as an extension of previously-seen benefits or in areas specific to interpretation. The present study examined professional interpreters (N = 23) and matched multilinguals (N = 21) on memory tests, the color-word Stroop task, the Attention Network Test, and a non-linguistic task-switching paradigm. The interpreters did not show advantages in conflict resolution or switching cost where bilingual benefits have been noted. However, an interpretation-specific advantage emerged on the mixing cost in the task-switching paradigm. Additionally, the interpreters had larger verbal and spatial memory spans. Interpreters do not continue to garner benefits from bilingualism, but they do appear to possess benefits specific to their experience with simultaneous interpretation

Working memory and its role in children’s scholastic attainment

Previous research has identified links between working memory and scholastic skills. This thesis reports five studies that investigated both the role of working memory in children's scholastic attainment and the resources that underlie working memory task performance. Study 1 demonstrated that both verbal and nonverbal working memory were important predictors of children's academic achievement at 11 and 14 years of age. Study 2 provided evidence for the utility of working memory as a predictor of later academic achievement. Study 3 demonstrated a distinction between the executive processes of inhibition and updating working memory, both of which were uniquely related to children'sscholastic attainment scores. Study 4 revealed that both speeds of processing and working memory span scores predicted unique variance in children's educational attainment. The relationships between speed and span in tasks varying in difficulty were also explored. Speed and span did not always conform to the same linear relationship. Study 5 explored a metric of cognitive cost suggesting that working memory task performance is determined by the difficulty of the retrievals required and the number of these retrievals divided by the time allowed to perform them. The results demonstrated that working memory task performance is constrained by temporal duration and the nature of processing activities. The results were discussed in terms of implications for models of working memory and implications for educational practice