When hearing spoken language, listeners segment the speech stream into speech sounds and assign each sound to a phoneme category. Recent research has shown that individuals differ in how they perform this task; some listeners can make categorical decisions while maintaining fine-grained acoustic information, while others seem to take a more step-like approach, according to which, they ignore acoustic information within phoneme categories. In other words, taking the speech sound /b/ as an example, some listeners are better than others in telling apart a good instance of a /b/ sound compared to a not-as-clear /b/. According to traditional views, listeners’ speech perception is tuned to the phoneme categories of their native language such that between-category differences are amplified, while –in contrast– listeners learn to ignore within-category differences. In this context, perceptual sensitivity to within-category differences has been considered a marker of suboptimal speech processing; however, recent work suggests that perceptual sensitivity may actually be a helpful aspect of speech processing. This fellowship examined perceptual sensitivity to within-category differences in the context of multilingual environments.
This project pursued three main objectives: (1) To examine how individual differences in speech processing affect learning of novel phonological contrasts, and –ultimately– individuals’ ability to reach a high level of proficiency in a foreign language, (2) To examine whether individual differences in speech processing ultimately affect listeners’ ability to learn foreign words, and (3) To assess the degree to which exposure to different phonologies affects the flexibility of the speech processing. For this purpose, a combination of cutting-edge experimental behavioral and neurophysiological tasks were used.
This research has several implications. First, it enriches our understanding about the fundamental mechanisms of speech perception. Recent work has revealed that –contrary to traditional views– maintaining within-category acoustic information may be an important aspect of spoken language comprehension. The results of this research project further enrich and expand on this literature by examining these processes in a multilingual population. Second, the results of this project demonstrate that high sensitivity to within-category information predicts higher achieved proficiency in a foreign language. Moreover, this relationship held over and above the effects of other predictors such as the amount of time dedicated to learning the new language. Third, it was found that bilingual status also plays an important role in terms of predicting foreign language proficiency; specifically, we found that early bilingualism and high sensitivity to within-category acoustic information each predict foreign language proficiency in the absence of the other. Thus, this research has made significant contributions in helping us identify the factors that facilitate foreign language learning.
