Extraretinal eye position signals determine perceived target location when they conflict with visual cues

To examine the role of extraretinal eye position information (EEPI) in visual perception of target location in normal room illumination, subjects participated in experiments in which EEPI was manipulated using the eye press maneuver with either monocular or binocular viewing. The viewing condition and eye press caused EEPI and retinal information about target location to conflict. Pointing responses in eye press trials were all in the direction of EEPI showing that EEPI is the dominant source of information in egocentric visual space perception. In binocular viewing, version and vergence occur in response to the eye press to maintain fusion and EEPI based on these movements also determine perceived location. An unanticipated finding was that the eye press was variable in its effectiveness in rotating the eye, which contributed to large variability in pointing errors and suggested the method would be a poor choice for future work.