Visual and proprioceptive shifts in perceived egocentric direction induced by eye-position.

The relation of three main effects of eye-position on perceived direction was investigated using a method of hand pointing in the horizontal plane: (1) Retinal eccentricity is overestimated with respect to the fovea by a constant factor of 2.6 degrees; (2) an extraretinal signal induces a shift in perceived visual direction (slope 0.12) that is opposite to the direction of eccentric gaze; and (3) the perceived position of the median plane of the head shifts toward the direction of eccentric eye-position (slope 0.23) while perceived trunk position remains unchanged.