Motion parallax is computed in the updating of human spatial memory

Abstract

As we move through space, stationary objects around us show motion parallax: their directions relative to us change at different rates, depending on their distance. Does the brain incorporate parallax when it updates its stored representations of space. We had subjects fixate a distant target and then we flashed lights, at different distances, onto the retinal periphery. Subjects translated sideways while keeping their gaze on the distant target, and then they looked to the remembered location of the flash. Their responses corrected almost perfectly for parallax: they turned their eyes farther for nearer targets, in the predicted nonlinear patterns. Computer simulations suggest a neural mechanism in which feedback about self-motion updates remembered locations of objects within an internal map of three-dimensional visual space.