Contextual effects in infant speech perception.

Infants, aged 2 to 4 months, discriminated synthetic speech patterns that varied in duration of the formant transitions; this variation provides information sufficient to signal the phonetic distinction between a stop consonant and a semivowel in adult listeners. In addition, the discriminability of a given difference in transition duration was a function of both the particular stimulus values and the total duration of the syllable. This contextual effect occurred even though the information for syllable duration came after the transition information. The obtained pattern of discontinuous discriminability was in accord with perception that is relational and categorical.