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Abstract:
Behavioral studies in our laboratory and others show that
between 7 and 11 months of age, infants' speech perception
abilities undergo a dramatic shift. At 7 months of age, infants
discriminate phonetic contrasts drawn from many languages,
including ones they have never heard. By 11 months, infants'
abilities to discriminate native language contrasts improve
significantly, while their foreign language discrimination
abilities decline. In this study, the mismatch negativity (MMN),
identified as an event-related potential (ERP), was used to test
infants at the two ages to examine neural substrates of speech
processing. Using the oddball paradigm, scalp potentials were
collected from 20 sites using electro-caps and Neuroscan Synamps
and Scan 4.0 software. Infants at both ages were tested with a
Mandarin Chinese and an English contrast using a between-groups
design. Results show reliable differences in the ERPs to native vs
foreign language contrasts at 11 months, but not at 7 months,
suggesting that between 7 and 11 months, the infant brain has begun
to show language-specific processing.
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