Measuring the perceptual magnet effect in the perception of vertical bar ivertical bar by German listeners

In a study of the internal category structure of the vowel /i/, Kuhl found a "perceptual magnet effect": Discrimination sensitivity was poorer for cat egory instances that were acoustically similar to the category prototype th an it was for category instances that were not. The typicality of category exemplars was determined by goodness judgments and was found to correlate w ith the acoustics of average production. Analysis and interpretation of dis crimination performance relied on two important assumptions: that listeners perceived all stimuli presented as exemplars of the same vowel category an d that, apart from the influence of phonetic coding, discrimination sensiti vity was the same across the investigated part of the vowel space. In the p resent study, it is shown that production and perception estimates of the c ategory prototype may diverge, possibly because listeners seem to prefer hy perarticulated variants of vowel categories. An approach towards measuremen t of intra-category discrimination minima is put forward and tested that pr otects against intercategory confounds and avoids the isosensitivity assump tion.