Abstract:

Listening to language during the first year of life has a dramatic effect on infants' perception of speech. With increasing exposure to a particular language, infants begin to ignore phonetic variations that are irrelevant in their native language. To examine these effects, 72 American and Japanese infants were tested at two ages, 6--8 months and 10--12 months, with synthetic versions of the American English /r/ and /l/ consonants. The /r--l/ contrast is not phonemic in Japanese. In both countries, the same experimenters, technique (head-turn conditioning), and stimuli were used. The results revealed two significant effects. The first shows the impact of language experience on speech perception. At 6--8 months of age, American and Japanese infants did not differ. Both groups performed significantly above chance (American M=63.7%; Japanese M=64.7%). By 10--12 months of age, American infants demonstrated significant improvement relative to performance at 6--8 months (M=73.8%), while Japanese infants declined (M=59.9%). Second, performance varied significantly as a function of the direction of stimulus change (/l/ to /r/ easier than the reverse), regardless of age or language experience. Discussion will focus on separating effects attributable to linguistic and psychoacoustic factors. [Work supported by NIH.]