Selective attention modulates electrical responses to reversals of optic-flow direction

Attended stimuli typically evoke larger event-related potentials (ERPs) than unattended stimuli. We previously reported an exception when an optic-flow pattern is interleaved with stationary dots. Reversals of motion direction evoked a larger N200 peak when attention was directed to the stationary dots. We replicated and further characterized this result: the N200 enhancement was eliminated when the dots moved randomly rather than in optic flow. The effect was also attenuated with isoluminant stimuli. Electrical source analysis suggested the attentional modulation of a configuration of dorsal extrastriate generators. The ERP evoked by reversals of optic flow may reflect the operation of independently configurable attentional filters within visual cortex.