Some perceptual dependencies in speeded classification of vowel color and pitch.

Wood (1975) suggested that information specifying consonant identity is dependent on the earlier processing of pitch. Is vowel identification also dependent on the prior processing of pitch? In contrast with the results obtained with consonants, Kuhl (1975, 1976) reported that infants responded selectively to differences in vowel color when pitch varied but not to differences in pitch when vowel color varied. Miller (1978) has also reported that adults show mutual, symmetric interference effects in speeded classification of vowel color and pitch. In the present study, judgments of vowel color and pitch were examined in a reaction time task in order to assess the effects of the relative discriminability of vowel and pitch quality on speeded classification. In addition, we also compared the classification of isolated vowels to vowels in consonantal context. The overall results were consistent with both Kuhl’s and Miller’s earlier findings but refine our understanding of the interaction between various dimensions by showing that vowel identification is also dependent on the processing of pitch information. Such an interaction, however, becomes evident only when the processing dependencies are examined across a wide range of stimulus values for each dimension. The present findings provide additional information about the nature of processing dependencies among dimensions in speech and the methods by which such dependencies may be studied.