Molnar, M. & Mayor, J.
Basque Center on Cognition, Brain and Language, Donostia - San Sebastian, SPAIN
In the field of bilingual speech perception, recent behavioral and electrophysiological data on simultaneous bilinguals suggest that they do not always exhibit abilities similar to those of the native monolinguals of the same languages (i.e., Guion, 2003; Molnar et al, 2009a,b; Sundara and Polka, 2008), despite the fact that simultaneous bilinguals are native users of both of their languages as well. As opposed to second language users, who often assimilate the acoustically similar non-native phonetic categories to their native ones, simultaneous bilinguals rather tend to dissimilate the phonetically similar sounds that occur across both languages. Importantly, the categories developed for the same speech sounds by native bilinguals do not completely overlap with those developed by the native monolinguals.
In order to understand the mechanism underlying the phonemic category formation of simultaneous bilingual language users at the perceptual level across their two languages, we modeled the unsupervised formation of the phonetic perceptual space of English-French bilinguals by training self-organizing maps (SOMs) with vowels from both languages at the same time. Similarly, we modeled the formation of phonetic categories in monolinguals by training SOMs with vowels from either French or English alone. Differences in the perception of speech segments in the bilingual SOMs with respect to the monolingual SOMs are discussed, and compared to experimental findings. The overall findings suggest that native bilingual and monolingual users of the same language rely on different perceptual systems of the same phoneme inventory.