How robust are lexical effects on phonetic categorization?

Abstract

Previous work has shown that lexical knowledge (whether a stimulus token makes a word or nonword) influences phonetic categorization (e.g., Fox, 1984). Recent work in our lab examined the effect of lexical influences on speech perception using two tasks (phoneme identification and AXB discrimination) and uncovered some unexpected findings. Listeners who performed identification first showed a robust effect of lexical status on phonetic categorization. However, listeners who performed the discrimination task first showed no effect of lexical status. Since prior research has shown that the lexical effect is fairly robust (see Pitt and Samuel,1993), the finding that the influence of lexical status can be eliminated by first placing listeners in an AXB discrimination task is the focus of the current research. The AXB task may focus attention on the prelexical, phonetic representation and differences within each phonetic category. This, in turn, eliminates the influence of higher level processes on phonetic perception in the identification task. The present study seeks to replicate this finding and investigate whether other lexical influences on perception (the influence of lexical neighborhood) are also altered by experience with AXB discrimination. Results are discussed in terms of the flow of information during phonetic perception and word recognition.