Transitional probability, not lexical knowledge, influences compensation

Abstract

The perceptual system compensates for fricative–stop coarticulation. Ambiguous stops between /t/ and /k/ tend to be heard as /k/ after /s/-final words and as /t/ after /S/-final words, even when the word–final fricatives are replaced with an ambiguous phoneme [J. L. Elman and J. L. McClelland, J. Mem. Lang. 27, 143–165 (1988)]. Biases in the transitional probabilities (TPs) of /s/ and /S/ in the words in that study mean that the effect following ambiguous fricatives could be due either to lexical involvement in prelexical compensation for coarticulation or to a sensitivity to TP at the prelexical level. In three experiments, listeners categorized nonword–final fricatives with TP biases, word–final fricatives where TPs were controlled, and word–initial stops following both fricative contexts. Categorization of ambiguous fricatives and stops was influenced by the TPs of the fricatives in the nonwords. But although there was a lexical bias in the categorization of the word–final ambiguous fricatives, there was no lexical influence on the categorization of the stops. These results suggest that the lexicon does not influence prelexical processing, and that the prelexical level is sensitive to TP. [Work supported by NIDCD, the Human Frontiers Science Project, and the Max Planck Society.]