Perceptual Categories for Musiclike Sounds: Implications for Theories of Speech Perception

Abstract

Sawtooth acoustic stimuli of different rise times are identified as coming from a plucked string instrument (pluck) or a bowed one (bow). Like stop consonants, these sounds are perceived categorically—discrimination is poor for stimuli identified as belonging to a single class but good for those identified as members of different classes. Varying the interval between two successive musiclike stimuli hardly alters discrimination. Sawtooth stimuli lasting 750 ms are clearly perceived categorically; those lasting 250 ms are not. Prolonged exposure to a pluck or bow stimulus can shift the rise-time boundary between categories. Shifts due to such selective adaptation decrease as adapting and test stimuli share fewer characteristics. Adaptation of postulated “feature detectors” therefore may occur in input systems prior to the detectors themselves. Our findings contradict previous claims that categorical perception and selective adaptation are manifestations of psychological processes unique to speech perception.