Detection of audiovisual speech correspondences without visual awareness

Abstract

Mounting physiological and behavioral evidence has shown that the detectability of a visual stimulus can be enhanced by a simultaneously presented sound. The mechanisms underlying these cross-sensory effects, however, remain largely unknown. Using continuous flash suppression (CFS), we rendered a complex, dynamic visual stimulus (i.e., a talking face) consciously invisible to participants. We presented the visual stimulus together with a suprathreshold auditory stimulus (i.e., a voice speaking a sentence) that either matched or mismatched the lip movements of the talking face. We compared how long it took for the talking face to overcome interocular suppression and become visible to participants in the matched and mismatched conditions. Our results showed that the detection of the face was facilitated by the presentation of a matching auditory sentence, in comparison with the presentation of a mismatching sentence. This finding indicates that the registration of audiovisual correspondences occurs at an early stage of processing, even when the visual information is blocked from conscious awareness.