ASA 127th Meeting M.I.T. 1994 June 6-10

4aMU8. Within-category discrimination of musical chords: Perceptual magnet or anchor?

Barbara E. Acker

Richard E. Pastore

Michael D. Hall

Dept. of Psychol., SUNY at Binghamton, Binghamton, NY 13901

Recent speech research has demonstrated that the presence of prototypes may be reflected in the internal structure of speech categories. Some speech results have found lower discrimination in a vowel P context compared to a NP context, suggesting that a prototype may function as a perceptual magnet, effectively decreasing perceptual distance, and thus, discriminability, between stimuli. The current study examines the function of prototypes in a musical category; another natural, but nonspeech, category. Prototype (P) and nonprototype (NP) sets of major triad stimuli were constructed, with stimuli in the P set being more representative of the category than the NP stimuli. 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 from the discrimination task demonstrated better performance in the prototype context. The current nonspeech results appear to follow predictions based on classification and perceptual models (to be discussed), and provide a natural, nonspeech contrast to speech findings. The results will also be addressed in terms of music perception, including aspects such as different temperment systems and the differential importance of chord components.