Perceptual-magnet effect as categorical perception

Abstract

The perceptual-magnet effect has received a great deal of attention in recent years as a possible foundation for phonetic category acquisition. This effect is based upon studies showing that category goodness affects intracategory discriminability. Unfortunately, there is a possible confound in many of these demonstrations. Whereas category identity and goodness ratings are collected for stimuli presented in isolation, discrimination scores are obtained for stimulus pairs. In the present study, vowel identification and goodness ratings were obtained from the same stimulus pairs that would later be presented in an AX discrimination task. Stimuli were identical to the vowel vector used by Iverson and Kuhl [J. Acoust. Soc. Am. 97, 553–561 (1995)]. Identification functions varied substantially as a function of the pairings in a manner that may be described as contrastive. Vowels labeled as /e/ when presented with a good /i/ exemplar were labeled as /i/ when presented with a good /e/. These identification functions were used to predict discrimination scores based solely on perceived phonemic identity. Predictions accounted for all of the difference in discriminability between prototypical and nonprototypical exemplars. Perceptual-magnet effects appear to be little more than classic categorical perception. [Work supported by NSF.]