Perception of Auditory, Visual, and Egocentric Spatial Alignment Adapts Differently to Changes in Eye Position

1 Departments of Neurobiology and Anatomy and 2 Biomedical Engineering, 3 Center for Navigation and Communication Sciences, and 4 Center for Visual Science, University of Rochester Medical Center, Rochester, New York Submitted 9 June 2009; accepted in final form 13 October 2009 ABSTRACT Vision and audition represent the outside world in spatial synergy that is crucial for guiding natural activities. Input conveying eye-in-head position is needed to maintain spatial congruence because the eyes move in the head while the ears remain head-fixed. Recently, we reported that the human perception of auditory space shifts with changes in eye position. In this study, we examined whether this phenomenon is 1 ) dependent on a visual fixation reference, 2 ) selective for frequency bands (high-pass and low-pass noise) related to specific auditory spatial channels, 3 ) matched by a shift in the perceived straight-ahead (PSA), and 4 ) accompanied by a spatial shift for visual and/or bimodal (visual and auditory) targets. Subjects were tested in a dark echo-attenuated chamber with their heads fixed facing a cylindrical screen, behind which a mobile speaker/LED presented targets across the frontal field. Subjects fixated alternating reference spots (0, ±20°) horizontally or vertically while either localizing targets or indicating PSA using a laser pointer. Results showed that the spatial shift induced by ocular eccentricity is 1 ) preserved for auditory targets without a visual fixation reference, 2 ) generalized for all frequency bands, and thus all auditory spatial channels, 3 ) paralleled by a shift in PSA, and 4 ) restricted to auditory space. Findings are consistent with a set-point control strategy by which eye position governs multimodal spatial alignment. The phenomenon is robust for auditory space and egocentric perception, and highlights the importance of controlling for eye position in the examination of spatial perception and behavior. Address for reprint requests and other correspondence: G. D. Paige, Department of Neurobiology and Anatomy, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave., Box 603, Rochester, NY 14642-8603 (E-mail: gary_paige{at}urmc.rochester.edu ).