How Lexical Stress Affects Speech Segmentation and Interactivity: Evidence from the Migration Paradigm

Current models of word recognition differ on the potential influence of lexical knowledge on sublexical processes. The present study addresses this issue through a paradigm based on the perceptual ‘‘migration’’ of linguistic units between two stimuli presented simultaneously, resulting in an illusory percept. For example, ‘‘kinrtrorverrsy’’ and ‘‘bosrglorrarfe’’ were played at the same time, with subjects judging, in one condition, if ‘‘controversy’’ was presented and, in another condition, if ‘‘bisrglorrarfe’’ was presented. The results showed that, in dichotic listening, the migration of the vowel, leading to erroneous detection of the prespecified target, occurred less often with real word targets than with nonsense word targets. However, when the two items of the pairs were played in both ears at different amplitudes so that they were perceived to be closer to each other than in the dichotic situation, the lexical effect only remained when the mispronounced phoneme was in an unstressed syllable. This observation suggests that the mispronunciation of stressed syllables of words impairs lexical access in such a way that no lexical influence on early processing stages is possible. In contrast, the mispronunciation of unstressed syllables does not affect lexical access, thus allowing the lexical influence to take place. These results are problematic for temporally sequential (left-to-right) models of lexical access. Rather, they support models that include the stress patterns of words as an important aspect of both lexical access and the interaction between sublexical and lexical knowledge.