THE PERCEPTUAL MAGNET EFFECT AS AN EMERGENT PROPERTY OF NEURAL MAP FORMATION

The perceptual magnet effect is one of the earliest known language-spe cific phenomena arising in infant speech development. The effect is ch aracterized by a warping of perceptual space near phonemic category ce nters. Previous explanations have been formulated within the theoretic al framework of cognitive psychology. The model proposed in this paper builds on research from both psychology and neuroscience in working t oward a more complete account of the effect. The model embodies two pr incipal hypotheses supported by considerable experimental and theoreti cal research from the neuroscience literature: (1) sensory experience guides language-specific development of an auditory neural map, and (2 ) a population vector can predict psychological phenomena based on map cell activities. These hypotheses are realized in a self-organizing n eural network model. The magnet effect arises in the model from langua ge-specific nonuniformities in the distribution of map cell firing pre ferences. Numerical simulations verify that the model captures the kno wn general characteristics of the magnet effect and provides accurate fits to specific psychophysical data. (C) 1996 Acoustical Society of A merica.