Influence of categories on perception 1 Running head: INFLUENCE OF CATEGORIES ON PERCEPTION The influence of categories on perception: Explaining the perceptual magnet effect as optimal statistical inference

A variety of studies have demonstrated that organizing stimuli into categories can affect the way the stimuli are perceived. One such effect is the perceptual magnet effect, in which discriminability between vowels is reduced near prototypical vowel sounds. We present a Bayesian model to explain why this reduced discriminability might occur: it arises as a consequence of optimally solving the statistical problem of perceiving speech sounds in the presence of noise. In the optimal solution to this problem, listeners’ perception of speech sounds is biased toward the means of phonetic categories because they use knowledge of these categories to guide their inferences about speakers’ target productions. Simulations show that model predictions closely correspond to previously published human data, and novel experimental results provide evidence for the predicted link between perceptual warping and speech signal noise. Several parallels are noted between this model and previous analyses of the perceptual magnet effect, and its implications for other effects of categories on perception are discussed.