Interactions in Bilingual Speech Processing.

摘要

This dissertation examined the extent to which the bilingual speech processing system is interactive.;Experiment 1 investigated whether properties of specific words bilinguals produce---e.g., cognate status---influenced interactions between native (L1) and second language (L2) phonetic systems. Analysis of voice onset times (VOTs) revealed that bilinguals were better at approximating L2 phonetic norms in producing cognates---translations overlapping in form and meaning (English 'canoe' vs. Portuguese 'canoa' )---relative to noncognates---translations overlapping in meaning only (English 'table' vs. Portuguese 'mesa' )---and, false-cognates---cross-linguistic neighbors overlapping in form only (English 'bald' vs. Portuguese 'balde' , meaning 'bucket'). This suggests that (i) lexical properties do influence the interaction of L1 and L2 phonetic systems, and (ii) both cascading activation from the semantic system and feedback activation from the sub-lexical system may be required for facilitation effects to arise.;Experiment 2 investigated the influence of semantics on sub-lexical processing by examining the extent to which access to semantic information affects bilinguals' judgments of phonological similarity. Analysis of phonological similarity ratings revealed that absence of semantic knowledge/overlap between word-pairs (e.g., unknown words, false-cognates) led bilinguals to perceive them as less similar relative to monolinguals' perception (semantic-unbiased) of the same stimuli. This indicates bilinguals' inability to judge phonological similarity based purely on form information.;Finally, Experiment 3 examined whether sub-lexical processes are modulated by differences in task demands by contrasting a semantically--driven vs. an orthographydriven task. Analysis of VOTs revealed task dissociation in monolingual, but not bilingual processing---monolinguals produced longer VOTs in picture naming relative to word reading. Speech rate is ruled out as a potential source for this dissociation. Results are discussed in terms of attentional mechanisms and cognitive effort: picture naming requires greater attention and greater cognitive effort from speakers and this greater effort in monolingual processing is reflected in the longer VOTs. Bilinguals' accurate pronunciation of L2 words requires them to operate at the top of their cognitive abilities regardless of language context.;Together these three experiments lend support to the interactive character of the bilingual speech processing system. Discussion is extended to parallels between bilingual and monolingual processing systems.