L1 Japanese Perceptual Drift in Late Learners of L2 English

This study presents evidence of second language (L2) influence on first language (L1) perception of alveolar stops. Sixty-one L1 Japanese late learners of L2 English (onset similar to 12 years old) in Japan (N = 31) and in the US (N = 30) participated. We examined late L2 learners ' L2 perceptual ability and L1 perception drift by administering three perception tasks (AX discrimination, forced categorization, and goodness rating) on word-initial stop consonants. The L2 learners ' L1 Japanese and L2 English data were compared to those of Japanese and English monolinguals, respectively (N = 21, N = 16). All participants' production data were also gathered to examine potential perception-production relationships. Late learners ' sensitivity patterns along a synthesized /da-ta/ continuum differed significantly from those of monolingual speakers, with a sensitivity peak location between the monolingual Japanese and English groups. This suggests that late learners ' voicing category boundaries may have been influenced by L2 English learning. The L2 learners ' goodness rating patterns of L1 Japanese stimuli also showed evidence of L1 perceptual drift: L2 learners tended to be more accepting of Japanese stimuli with longer VOTs compared to Japanese monolinguals.