Asymmetric lexical access and fuzzy lexical representations in second language learners

For L2 learners, confusable phonemic categories lead to ambiguous lexical representations. Yet, learners can establish separate lexical representations for confusable categories, as shown by asymmetric patterns of lexical access, but the source of this asymmetry is not clear (Cutler, Weber, & Otake, 2006). Two hypotheses compete, situating its source either at the lexical coding level or at the phonetic categorization level. The lexical coding deficiency hypothesis suggests that learners' encoding of an unfamiliar category is not target-like but makes reference to a familiar L1 category (encoded as a poor exemplar of that L1 category). Four experiments examined how learners lexically encode confusable phonemic categories. American English learners of Japanese and of German were tested on phonetic categorization and lexical decision for geminate/singleton contrasts and front/back rounded vowel contrasts. Results showed the same asymmetrical patterns as Cutler et al.'s (2006), indicating that learners encode a lexical distinction between difficult categories. Results also clarify that the source of the asymmetry is located at the lexical coding level and does not emerge during input categorization: the distinction is not target-like, and makes reference to L1 categories. We further provide new evidence that asymmetries can be resolved over time: advanced learners are establishing more native-like lexical representations.