THE LOCUS OF THE LEXICAL SHIFT IN PHONEME IDENTIFICATION

The lexical identification shift is used as a measure of speech proces sing in the phoneme identification task (W. F. Ganong, 1980). Interact ive (bottom-up and tap-down) models of word recognition account for th e shift by claiming that lexical knowledge feeds back to a prelexical level and aids speech processing. Autonomous models (bottom-up only) m aintain that the shift arises by other means and at later stages of pr ocessing. The locus of the lexical shift was investigated by using det ection theory analysis procedures to measure perceptual changes in pho neme processing. Lexical status (word-nonword) of the utterance was va ried in Experiments 1 and 3 and was found to influence phoneme process ing. In Experiment 2 the effects of a postperceptual manipulation, mon etary payoff, did not show up in the detection theory analysis. Implic ations of the results for both classes of models are discussed.