Abstract: Phoneme perception in Abstract fluent speech is constrained andfacilitated by higher-level processing. The experiments used the paradigmof phoneme categorization to investigate the role of the lexicon and thesyllable in speech perception. In particular, they examined whether thelexical effect on phoneme perception found previous?y by Ganong (1980)could also be found in polysyllabic words, and whether such an effectwas influenced by the presence of shorter words embedded within thepolysyllabic words. The experiments also investigated how the lexicaleffect in polysyllabic words was influenced by stimulus repetition andsubjects' expectations. The results of experiments 1 and 2 showed a significant effect ofthe lexical status of the whole stimulus on phoneme categorization,but revealed no influence of the subjects' expectation on the higher-levelconstraints. The results of experiment 2 demonstrated the decay of thelexical effects with stimulus repetition. The implications of these results are discussed for speechand phoneme perception theories.

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