Motion components of VEPs to the waggon wheel effect

Visual evoked potentials (VEPs) from eight subjects are presented from scalp sites O1, O2, T5, T6, P3 and P4. A spoked wheel was illuminated by a constantly flashing strobe. By adjusting the real angular speed of the wheel the subjective impression was given of; a stationary wheel, a wheel spinning slowly or spinning rapidly clockwise. Two visually identified components, a negativity and a positivity, were found to be of larger amplitude in response to motion. The results were interpreted as consistent with a model of AM proposing motion information to be processed within the visual system.