ERP correlates of processing native and non-native language word stress in infants with different language outcomes.

The early acquisition of native language prosody is assumed to ease infants' language development. In a longitudinal setting we investigated whether the early processing of native and non-native language word stress patterns is associated with children's subsequent language skills. ERP data of 71 four- and five-month-old infants were retrospectively grouped according to children's verbal performance in a language test at 2.5 years. Children who displayed age-adequate expressive language skills later in development showed both an early and a late negative mismatch response (MMR) when processing the native language stress pattern as deviant in a passive oddball design. Children with poor language skills later in development did not show these negativities. Both groups displayed an infant-specific positive MMR to the non-native language deviant. This positivity was enhanced and prolonged in children who showed poor language skills later in development as compared to children who showed normal language skills. The results indicate that variability in expressive language development has precursors in infants' ERP correlates of word stress processing.