Visual Target Localization, the Effect of Allocentric Audiovisual Reference Frame

Visual allocentric references frames (contextual cues) affect visual space perception (Diedrichsen et al., 2004; Walter et al., 2006). On the other hand, experiments have shown a change of visual perception induced by binaural stimuli (Chandler, 1961; Carlile et al., 2001). In the present study we investigate the effect of visual and audiovisual allocentred reference frame on visual localization and straight ahead pointing. Participant faced a black part-spherical screen (92cm radius). The head was maintained aligned with the body. Participant wore headphone and a glove with motion capture markers. A red laser point was displayed straight ahead as fixation point. The visual target was a 100ms green laser point. After a short delay, the green laser reappeared and participant had to localize target with a trackball. Straight ahead blind pointing was required before and after series of 48 trials. Visual part of the bimodal allocentred reference frame was provided by a vertical red laser line (15° left or 15° right), auditory part was provided by 3D sound. Five conditions were tested, no-reference, visual reference (left/right), audiovisual reference (left/right). Results show that the significant effect of bimodal audiovisual reference is not different from the visual reference one