Abstract
Lexical knowledge influences how human listeners make decisions about speech sounds. Positive lexical effects (faster responses to target sounds in words than in nonwords) are robust across several laboratory tasks, while negative effects (slower responses to targets in nonwords that are more like words than in nonwords that are less like nonwords) have been found in phonetic decision tasks but not phoneme monitoring tasks. Are negative lexical effects therefore a task-specific consequence of the forced choice required in phonetic decision? The present experiments refuted this hypothesis. We compared phoneme monitoring and phonetic decision performance using exactly the same Dutch materials. In both tasks there were positive lexical effects, but no negative lexical effects. In studies showing negative lexical effects, the materials were made by cross-splicing, and therefore contained evidence supporting the lexically-consistent phonemes. The present materials were not made by cross-splicing. We therefore argue that lexical knowledge only influences phonemic decision-making when there is evidence for the lexically-consistent phoneme in the speech signal.
