Boston University Center for Adaptive Systems and Department of Cognitive and Neural Systems
Abstract
The McGurk effect has generally been studied within a limited range of phonetic contexts. With the goal of characterizing the McGurk effect through a wider range of contexts, a parametric investigation across three different vowel contexts, /i/, /α/, and /u/, and two different syllable types, consonant-vowel (CV) and vowel-consonant (VC), was conducted.
This paper discusses context-dependent changes found specifically in the McGurk fusion phenomenon (Part II addresses changes found in combination percepts). After normalizing for differences in the magnitude of the McGurk effect in different contexts, a large qualitative change in the effect across vowel contexts became apparent. In particular, the frequency of illusory /g/ percepts increased relative to the frequency of illusory /d/ percepts as vowel context was shifted from /i/ to /α/ to /u/. This trend was seen in both syllable sets, and held regardless of whether the visual stimulus used was a /g/ or /d/ articulation.
This qualitative change in the McGurk fusion effect across vowel environments corresponded systematically with changes in the typical second formant frequency patterns of the syllables presented. The findings are therefore consistent with sensory-based theories of speech perception which emphasize the importance of second formant patterns as cues in multimodal speech perception.National Institue on Deafness and other Communication Disorders (R29 02852); Alfred P. Sloan Foundation and National Institute on Deafness and other Communication Disorders (R29 02852
