DEPOLARIZING THE PERCEPTUAL MAGNET EFFECT

In recent years there has been a great deal of interest in demonstrati ons of the so-called ''Perceptual-Magnet Effect'' (PME). In these stud ies, AX-discrimination tasks purportedly reveal that discriminability of speech sounds from a single category varies with judged phonetic '' goodness'' Of the sounds. However, one possible confound is that categ ory membership is determined by identification of sounds in isolation, whereas, discrimination tasks include pairs of stimuli. In the first experiment of the current study, identifications and goodness judgment s were obtained for vowels (/i/-/e/) presented in pairs. A substantial shift in phonetic identity was evidenced with changes in the context vowel. In a second experiment, listeners participated in an AX-discrim ination task with the vowel pairs from the first experiment. Using the contextual identification functions from the first experiment, predic tions of discriminability were calculated using the classic tenets of Categorical Perception. Obtained discriminability functions were well accounted for by predictions from identification. There was no additio nal unexplained variance that required the proposal of ''perceptual ma gnets.'' These results suggest that PME may be nothing more than furth er demonstration that general discriminability is greater for cross-ca tegory stimulus pairs than for within-category pairs. (C) 1998 Acousti cal Society of America.