Visual evoked potentials to stimuli in apparent motion

Following an extensive single subject pilot study 12 Ss viewed a continuously cycling (3 Hz), two stimulus, apparent motion (AM) display. The "AM breakdown effect" was utilised to gather visual evoked potentials (VEPs) from sites O1, O2, T5, T6, P3, and P4 during periods in which the display elicited either: the percept of motion; or the percept of two discrete alternating stimuli. VEPs displayed components of larger amplitude during motion periods in all right (but no left) hemisphere sites during periods 60-82 msec post left field stimulus onset (positive component) and 100-126 msec post right field stimulus onset (negative component). Results were interpreted as indicating initial extraction of motion information within the occipital lobe, with further motion processing taking place in temporal and parietal lobes.