Description:

Both the timing (i.e., ‘when’) and amount (i.e., ‘how much’) of language exposure have been shown to affect language-learning outcomes. Monolinguals and (most) bilinguals confound early and extended exposure, as their first-acquired language is their most used (or dominant) language. This confound makes it difficult to isolate the benefits that either one of these exposure patterns could provide independently for language acquisition. Switched-dominance bilinguals (i.e., heritage speakers) dissociate early and extended exposure as their first-acquired language (L1) is considerably weaker (non-dominant) compared to their stronger (dominant) second-acquired language (L2). This dissociation allows us to examine the unique benefits of both early and extended exposure on language acquisition. The current study focuses on how these exposure patterns affect speech and vocabulary learning in heritage speakers in three separate experimental paradigms. In Experiment 1, speech intelligibility scores of English and Spanish sentences produced by Spanish heritage speakers’ (SHS, L2-dominant English) were compared to L1-dominant English and Spanish controls under both easy (-4 dB signal-to-noise ratio, SNR) and difficult (-8 dB SNR) listening conditions. In Experiments 2 and 3, SHS performed both a lexical decision and single-word reading task in both English and Spanish along with L1-dominant English and Spanish controls, respectively. Words varied orthogonally on age of acquisition and lexical frequency, two factors known to affect word retrieval and production. Combined, these results suggest that the benefits of early exposure to language may be limited in some areas of speech and vocabulary processing. Additionally, extended language usage, resulting in language dominance, may be sufficient to overcome any processing difficulties incurred in the initial delay to the L2. Finally, these data challenge what is meant by the term “native speaker” when modeling bilingualism on an L1-L2 distinction, as such a dimension may be unable to accurately predict the linguistic performance of some bilingual speakers.