Differential perception of vowels and stop consonants in Spanish-English bilingual preschoolers

Despite extensive work on perceptual development in bilingual infants, we know little about speech perception in bilingual preschoolers. This study investigates English vowel and stop voicing perception in 20 Spanish-English bilingual preschoolers and 20 English monolingual peers. Perception was assessed through a forced-choice minimal-pair identification task in which children heard synthesized audio stimuli that varied systematically along an /i-ɪ/ vowel continuum and a/b-p/ Voice Onset Time (VOT) continuum and were asked to match them with one of two pictures for each contrast. The results of Bayesian mixed-effects logistic regression analyses indicated no credible difference in vowel perception between monolinguals and bilinguals. In contrast, the bilinguals’ category boundary for English /b-p/ was impacted by their experience with Spanish, with more short-lag VOT tokens being perceived as voiceless in line with Spanish VOT. We interpret the observed asymmetry as stemming from differences in L1-L2 mappings across the contrasts.