The Categorization of L3 Vowels Near First Exposure by Spanish-English Bilinguals

The present study examined the predictions the Perceptual Assimilation Model in the context of naive bilingual speakers while also considering whether the predictions of third language (L3) models of morphosyntax could be extended to L3 phonology. In particular, it was asked whether several groups of Spanish-English bilinguals (constituting a fully combined design) would categorize sounds in two unknown languages, French and German, using their first language (L1) categories, second language (L2) categories, or a combination of both. 199 participants took part in the study, who made up 4 total groups: L1 English-L2 Spanish (n = 55), L1 Spanish-L2 English (n = 59), English monolingual (n = 59) and Spanish monolingual (n = 29). The participants completed a vowel categorization task, where they were asked to match four vowel sounds in French and German to their existing English and Spanish categories. The results of a series of Bayesian Multinomial regression models suggested that bilinguals categorize L3 vowels using both L1 and L2 categories according to the acoustics of the input. There was no evidence of a clear bias for either the L1 or L2 when an L3 vowel exists in both the L1 and L2. Additionally, the bilingual English participants differed from English monolinguals in the their categorization of new language sounds. These results have implications for both the PAM-L2 and L3 models, by showing that the language learners are not solely guided by their native language, and have access to both L1 and L2 categories when accounting for novel language sounds.