WITHIN-CATEGORY DISCRIMINATION OF MUSICAL CHORDS - PERCEPTUAL MAGNET OR ANCHOR

Recent speech research has begun to evaluate the internal structure of categories. In one such study, Xuhl (1991) found that discrimination was poorer for vowel stimuli that were more representative of the cate gory (prototype, or P, set) than it was for less representative stimul i (nonprototype, or NP, set). This finding was interpreted as indicati ng that a category prototype may function as a ''perceptual magnet,'' effectively decreasing perceptual distance, and thus discriminability, between stimuli. The present study examines the function of prototype s in a musical category-another natural, but nonspeech category. Paral leling the Kuhl study, representative (P) and less representative (NP) sets of major triad stimuli were constructed, based on equal temperam ent. Musically experienced subjects rated the stimuli in each set for goodness as a major triad, with the highest rated stimulus serving as a prototype standard for a subsequent discrimination task. Results hom the discrimination task demonstrated better performance in the P cont ext than in the NP context. The current nonspeech results indicate tha t a prototype functions as an anchor rather than a magnet. In addition to providing a natural, nonspeech standard for comparison with speech findings, the results provide some important insights into the nature of musical categories.