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The present study examined acoustical and developmental influences on the categorical perception of /r/ and /w/. One group of adults, and three groups of normally developing preschool children, aged 3, 4, and 5 years, respectively, participated in three experimental conditions. These conditions involved performing a video-game identification task employing three different synthetic ‘‘rock-walk’’ continua. In condition I, the acoustic tokens varied according to both spectral and temporal cues; in condition II, the acoustic tokens varied only with respect to spectral cues; in condition III, the acoustic tokens varied only with respect to temporal cues. As hypothesized, changes in perceptual responses were seen as a function of both age and acoustical cue availability. Temporal cues, relative to spectral cues appeared to be the more salient cue for 3 yr olds, whereas for the 4 yr olds, 5 yr olds, and adults the two types of cues appeared to be equally salient. Other developmental trends evidenced included findings that children, relative to adults, demonstrate greater /r/ perceptual categories, more variable perceptual performance, and a tendency to base their phonemic categorizations on primarily only one cue.

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The purpose of the present study was to examine the development of categorical perception of phoneme boundaries. A seven-step adult /R-W/ continua was synthesized via the Klatt cascade/parallel software program. The acoustic tokens varied according to the second (F2)- and third (F3)-formant onset frequencies and second (F2)- and third (F3)-formant transition rates. Percentage of correct responses on an identification task was computed to yield a measure of phonemic boundary location for adults and children of 3, 4, and 5 years of age. The phonemic boundaries fell between stimuli 3 and 4, at stimulus 4 and 5 for 3-, 4-, and 5-year-old children and adults, respectively. The finding that there was a shifting and increasing steepness in the phonemic boundaries as a function of age is supportive of previous research and moreover, of the theory that a child's phonological system is not inherently different than that of an adult but rather is just a simpler or less precise version of the mature system.