Recent studies showed that eye position influences audio-visual fusion (Hartnagel et al., 2007) as well as auditory localization (Razavi et al., 2007). This behavioral data are based on electrophysiological results showing idiosyncratic neuronal representations in SC (Jay and Sparks 1984) as in cortical areas (Snyder, 2006). In the present experiment we investigate the effect of gaze position on visual and auditory target localization. These stimuli are displayed alone or in synchrony with a variable spatial disparity between them.
The subject is sat at the center of a hemi-cylindrical screen, the head, aligned with the body, is kept fixed using a bite-bar, and the gaze is monitored by an eye tracker. Three conditions are tested (intermixed); auditory alone trials, visual alone trials and bimodal AV trials. For each of the 3 conditions the fixation cross is displayed either straight ahead or 15° laterally shifted to the right (randomly intermixed) for a mean duration of 500 ms. Subject has to localize the visual and the auditory part of the stimuli using a trackball to move a white cross.
Results do not permit to show significant effect of eye position on auditory or visual localization.