The TRACE Model of Speech Perception

We describe a model called the TRACE model of speech perception. The model is based on the principles of interactive activation. Information processing takes place through the excitatory and inhibitory interactions of a large number of simple processing units, each working continuously to update its own activation on the basis of the activations of other units to which it is connected. The model is called the TRACE model because the network of units forms a dynamic processing structure called “the Trace,” which serves at once as the perceptual processing mechanism and as the system’s working memory. The model is instantiated in two simulation programs. TRACE 1. described in detail elsewhere. deals with short segments of real speech, and suggests a mechanism for coping with the fact that the cues to the identity of phonemes vary as a function of context. TRACE II, the focus of this article, simulates a large number of empirical findings on the perception of phonemes and words and on the interactions of phoneme and word perception. At the phoneme level, TRACE II simulates the influence of lexical information on the identification of phonemes and accounts for the fact that lexical effects are found under certain conditions but not others. The model also shows how knowledge of phonological constraints can be embodied in particular lexical items but can still be used to influence processing of novel, nonword utterances. The model also exhibits categorical perception and