STATISTICS OF GAZE FIXATION DISTRIBUTIONS WITHIN DYNAMIC FACES DURING AUDIOVISUAL SPEECH PERCEPTION

MARTIN PARE, DEPTS OF PHYSIOLOGY AND PSYCHOLOGY

Abstract
The human face is a multifaceted stimulus of particular significance for social communication, including audiovisual speech. To understand better the process of gathering facial information, we examined the spatial distribution of gaze fixations displayed by subjects performing audiovisual speech perception tasks while viewing dynamic talking faces. In a series of experiments, we found that gaze fixations are asymmetrically distributed, influenced by the nature of the task and the perceptual difficulty, but not necessarily correlated with perceptual accuracy. Although gaze tend to be directed more toward the lips of a talker during speech, high spatial frequency information afforded by direct oral foveation is not necessary for the successful processing of visual speech information. When speech intelligibility is decreased with acoustic noise, subjects minimize their gaze fixation distributions around the center of the talker’s face, which constitutes an ideal vantage point to process a face as a whole. These findings show that the process of gathering facial information is structured mostly because of the observer’s strategy rather than the stimulus itself and that it is not restricted to foveal image processing. This work emphasizes the importance of studying face processing with dynamic stimuli to simulate naturalistic communication conditions.

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