Neural Basis of The Double Drift Illusion

In the "double-drift" illusion, local motion within a window moving in the periphery alters the windows perceived path. The illusion is strong even when the eyes track a target whose motion matches the window so that the stimulus remains stable on the retina. This implies that the illusion involves the integration of retinal signals with non-retinal eye-movement signals. To identify where in the brain this integration occurs, we measured BOLD fMRI responses in visual cortex while subjects experienced the double drift illusion. We identified a number of cortical areas that responded more strongly during the illusion, but only in area hMT+ was it possible to decode the illusory trajectory. Our results provide evidence for a perceptual representation in human visual cortex that is not linked to retinal position.