Speech Perception, Word Recognition and the Structure of the Lexicon.

This paper reports the results of three projects concerned with auditory word recognition and the structure of the lexicon. The first project was designed to experimentally test several specific predictions derived from MACS, a simulation model of the Cohort Theory of word recognition. Using a priming paradigm, evidence was obtained for acoustic-phonetic activation in word recognition in three experiments. The second project describes the results of analyses of the structure and distribution of words in the lexicon using a large lexical database. Statistics about similarity spaces for high and low frequency words were applied to previously published data on the intelligibility of words presented in noise. Differences in identification were shown to be related to structural factors about the specific words and the distribution of similar words in their neighborhoods. Finally, the third project describes efforts at developing a new theory of word recognition known as Phonetic Refinement Theory. The theory is based on findings from human listeners and was designed to incorporate some of the detailed acoustic-phonetic and phonotactic knowledge that human listeners have about the internal structure of words and the organization of words in the lexicon, and how, they use this knowledge in word recognition. Taken together, the results of these projects demonstrate a number of new and important findings about the relation between speech perception and auditory word recognition, two areas of research that have traditionally been approached from quite different perspectives in the past.