Lallier, M. 1 , Thierry, G. 2 , Carreiras, M. 1 & Tainturier, M. 2
1 Basque Center on Cognition, Brain and Language, Donostia, Spain
2 School of Psychology, Bangor University, Wales, UK
During speech acquisition, specific acoustic features act as cues helping to segment and access the lexical forms embedded in speech streams. Therefore, the speed at which auditory automatic attentional focus engages and disengages may adapt depending on those acoustic cues present in the language acquired. The auditory stream segregation threshold is a measure of the shortest stimulus onset asynchrony (SOA) for which automatic attention can disengage and reengage between two successive different stimuli. Since such measure reflects automatic attention abilities underlying speech perception (Lallier et al., 2010), it may vary between different linguistic groups. The present study aimed at showing that early Welsh-English bilinguals show different auditory attentional shifting speed compared to English monolinguals.
We showed that 14 Welsh-English bilingual adults started to perceive two distinct segregated high- and low-pitch streams (instead of one-stream composed of high- and low-pitched sounds) at significantly slower SOAs (auditory segregation threshold = 136 ms) than 14 English monolingual adults (105 ms) matched one by one for age, non verbal IQ, and vocabulary skills. Interestingly, this significant effect was observed in absence of any group difference in a similar visual task, and regardless of lexical access speed of participants.
This study demonstrates that Welsh-English bilinguals may perceive auditory stimulus sequences differently from English monolinguals because of different auditory automatic attentional shifting speeds. We attribute such effects to variations regarding lexical stress distribution between Welsh (penultimate syllable) and English (initial syllable). These results suggest that perceptual and attentional mechanisms employed during auditory scene analysis are influenced by the language acquired. Linguistic specifics should therefore be taken into account for oral language impairments’ diagnostic and remediation.