Infants' discrimination of the duration of a rapid spectrum change in nonspeech signals.

Two-month-old infants discriminated complex sinusoidal patterns that varied in the duration of their initial frequency transitions. Discrimination of these nonspeech sinusoidal patterns was a function of both the duration of the transitions and the total duration of the stimulus pattern. This contextual effect was observed even though the information specifying stimulus duration occurred after the transitional information. These findings parallel those observed with infants for perception of synthetic speech stimuli. Specialized speech processing capacities are thus not required to account for infants' sensitivity to contextual effects in acoustic signals, whether speech or nonspeech.