Effects of lexical status on children’s and adults’ perception of native and non-native vowels

Monolingual, English-speaking 5-year-olds, 9-year-olds, and adults heard stimuli from two ‘‘native,’’ synthetic continua, in which the vowels ranged from English /i/ to /i/ in the context /b—b/ or /b—p/. Thus the endpoints of the first continuum constituted a word and a nonword (‘‘bib’’ vs *‘‘beeb’’); the reverse held for the second continuum (*‘‘bip’’ vs ‘‘beep’’). Other subjects heard stimuli from two ‘‘foreign’’ continua, where the vowels ranged from English /i/ to a foreign vowel /y/ in the contexts described above. Thus the endpoints of the first continuum corresponded to a word and a nonword (‘‘bib’’ vs *‘‘bYb’’); both endpoints of the second continuum corresponded to nonwords (*‘‘bip’’ vs *‘‘bYp’’). After training on endpoints, subjects’ identifications of the nine stimuli of a given continuum were examined to assess whether: children, like adults, exhibit a ‘‘lexical bias’’ effect for familiar vowels (from the ‘‘native’’ continua); vowel categories not bounded by another native vowel (as in the ‘‘foreign’’ continua) expand outward or become better defined with increasing age and/or lexical status.