Context effects in two-month-old infants' perception of labiodental/interdental fricative contrasts

We investigated 2-month-old infants' perception of a subset of highly confusable English fricatives. In Experiment 1, infants discriminated modified natural tokens of the voiceless fricative pair [fa]/[oa] but only when the syllables included their frication noises. They also discriminated the voiced pair [va]/[oa] both with and without fricative noises. These results parallel those found with adults by Carden, Levitt, Jusczyk, and Walley (1981). In Experiment 2 [f] and [o] noises were appended to [a], and the same [f] noise was appended to the previously indiscriminable fricationless versions of [fa] and [oa]. Infants discriminated both pairs of stimuli, indicating that (a) the frication is a sufficient cue for [fa]/[oa] discrimination and that (b) it provides a context for discriminating the [f] and [o] formant transitions. We conclude that infants' perception of labiodental/interdental fricative contrasts show evidence of context effects similar to those observed with adults.