Interactive use of lexical information in speech perception.

Two experiments are reported that demonstrate contextual effects on identification of speech voicing continua. Experiment 1 demonstrated the influence of lexical knowledge on identification of ambiguous tokens from word-nonword and nonword-word continua. Reaction times for word and non-word responses showed a word advantage only for ambiguous stimulus tokens (at the category boundary); no word advantage was found for clear stimuli (at the continua endpoints). Experiment 2 demonstrated an effect of a postperceptual variable, monetary payoff, on nonword-nonword continua. Identification responses were influenced by monetary payoff, but reaction times for bias-consistent and bias-inconsistent responses did not differ at the category boundary. An advantage for bias-consistent responses was evident at the continua endpoints. The contrasting patterns of reaction-time data in the two experiments indicate different underlying mechanisms. We argue that the lexical status effect is attributable to a mechanism in which lexical knowledge directly influences perceptual processes.