Categorical perception of tonal intervais: Musicians can’t tellsharp fromflat

Abstract

Six musicians with relative pitch judged 13 tonal intervals in a magnitude estimation task. Stimuli were spaced in .2-semitone increments over a range of three standard musical categories (fourth, tritone, fifth,). The judged magnitude of the intervals did not increase regularly with stimulus magnitude. Rather, the psychophysical functions showed three discrete steps cor-responding to the musically defined intervals. Although all six subjects had identified in-tune intervals with >95% accuracy, all were very poor at differentiating within a musical category— they could not reliably tell “sharp” from “flat.” After the experiment, they judged 63% of the stimuli to be “in tune,” but in fact only 23% were musically accurate. In a subsequent labeling task, subjects produced identification functions with sharply defined boundaries between each of the three musical categories. Our results parallel those associated with the identification and scaling of speech sounds, and we interpret them as evidence for categorical perception of music.