Dissociation of corollary discharge from gaze direction does not induce a straight-ahead shift

Pressure on the outer can thus of the eye can change the oculomotor innervation, and thus the corollary discharge, while a subject maintains monocular fixation on a visual target. We tested the possibility that sensory and motor effects of pressing an eye were due to a shift in the subjective straight-ahead direction. Subjects set an auditory source to straight ahead with and without a structured visual field and with and without eyepress. We also measured matching of auditory and visual targets under the same four conditions. Eyepress biased audio-visual matching with and without a structured field, but did not induce a straight-ahead shift. The deviation of the occluded eye was correlated with the amount of perceptual shift in audio-visual matching (r= .83). We conclude that perceptual offsets during eyepress are caused by a bias in extraretinal signals, and not by a cognitive straight-ahead shift.