Measuring the perceptual magnet effect in the perception of /i/ by German listeners

Abstract

In a study of the internal category structure of the vowel /i/, Kuhl found a "perceptual magnet effect": Discrimination sensitivity was poorer for category instances that were acoustically similar to the category prototype than it was for category instances that were not. The typicality of category exemplars was determined by goodness judgments and was found to correlate with the acoustics of average production. Analysis and interpretation of discrimination performance relied on two important assumptions: that listeners perceived all stimuli presented as exemplars of the same vowel category and that, apart from the influence of phonetic coding, discrimination sensitivity was the same across the investigated part of the vowel space. In the present study, it is shown that production and perception estimates of the category prototype may diverge, possibly because listeners seem to prefer hyperarticulated variants of vowel categories. An approach towards measurement of intra-category discrimination minima is put forward and tested that protects against intercategory confounds and avoids the isosensitivity assumption.

Directional asymmetries reveal a universal bias in adult vowel perception

“…Listeners consistently perceived the stimuli in a particular part of vowel space as better exemplars of /i/, indicating that the category has a graded, internal structure. Interestingly, the stimuli perceived as prototypic category members also matched the average acoustic production values of /i/ (Peterson & Barney, 1952), suggesting that there may be a close correspondence between the mean stimulus values experienced in the input signal and the stored prototype (although, this outcome conflicts with other studies, which show that prototypicality judgments are often more peripheral compared the the average production values reported in a corpus distribution [see, e.g., Johnson, Wright, & Flemming, 1993;Lively & Pisoni, 1997;Diesch, Iverson, Kettermann, & Siebert, 1999;Whalen, Magen, Pouplier, Kang & Iskarous, 2004]). …”

“…Recall that Kuhl (1991) found a close correspondence between the typicality of /i/ exemplars and the acoustics of average production (based on /i/ production estimates reported in Peterson and Barney [1952]; cf. Lively & Pisoni, 1997;Diesch et al, 1999).…”

The influence of categories on perception: Explaining the perceptual magnet effect as optimal statistical inference.

“…This supported previous analyses, suggesting that perceptual space was shrunk near category centers and expanded near category edges. The effect has since been replicated in the English /i/ category (Sussman & Lauckner-Morano, 1995), and evidence for poor discrimination near category prototypes has been found for the German /i/ category (Diesch, Iverson, Kettermann, & Siebert, 1999). In addition, the effect has been found in the /r/ and /l/ categories in English but not Japanese speakers (Iverson & Kuhl, 1996; Iverson et al, 2003), lending support to the idea of language-specific phonetic category prototypes.…”

A unified account of categorical effects in phonetic perception

“…There were documented replications of the perceptual magnet effect in the /i/ category in German (Diesch et al, 1999) and Swedish (Kuhl et al, 1992;Aaltonen et al, 1997), but also failed replication attempts for American English (Lively & Pisoni, 1997;Sussman & Gekas, 1997) and Australian English (Thyer et al, 2000). Additionally, there was a failure to find evidence of the perceptual magnet effect for certain other vowel categories in English (Thyer et al, 2000).…”