Lexical effects on phonetic categorisation have been taken as evidence that the listener's word knowledge influences phonetic processing during normal speech perception. The present study examined word-nonword effects in the categorisation of word-initial and word-final stop consonants. Natural speech was edited to produce bilabial, alveolar and velar voicing continue. The data revealed a significant word-nonword effect, such that subjects were more likely to categorise an ambiguous consonant as voiced if the voiced endpoint of the continuum was a word, but as unvoiced if the unvoiced endpoint of the continuum was a word. But it was found that within some blocks there was no evidence of this lexical shift. Subsequent experimental manipulations provided additional evidence that this shift is highly variable. The fact that the effect is nonmandatory provides support for the view that phonetic processing can occur independently of lexical processing.
Bibliographic reference. McQueen, James M. (1989): "The use of lexical knowledge in phonetic categorisation", In EUROSPEECH-1989, 2581-2584.