Effects of categorization and discrimination training on auditory perceptual space

Psychophysical phenomena such as categorical perception and the perceptual magnet effect indicate that our auditory perceptual spaces are warped for s ome stimuli. This paper investigates the effects of two different kinds of training on auditory perceptual space. It is first shown that categorizatio n training using nonspeech stimuli, in which subjects learn to identify sti muli within a particular frequency range as members of the same category, c an lead to a decrease in sensitivity to stimuli in that category. This phen omenon is an example of acquired similarity and apparently has not been pre viously demonstrated for a category-relevant dimension. Discrimination trai ning with the same set of stimuli was shown to have the opposite effect: su bjects became more sensitive to differences in the stimuli presented during training. Further experiments investigated some of the conditions that are necessary to generate the acquired similarity found in the first experimen t. The results of these experiments are used to evaluate two neural network models of the perceptual magnet effect. These models, in combination with our experimental results, are used to generate an experimentally testable p rediction concerning changes in the brain's auditory maps under different t raining conditions. (C) 1999 Acoustical Society of America. [S0001-4966(99) 00411-7].