Mechanisms of priming by masked stimuli: Inferences from event-related brain potentials

A metacontrast procedure was combined with the recording of event-related p otentials (ERPs) to examine the mechanisms underlying the priming effect ex -el-ted by masked visual stimuli (primes) on target processing,. Participan ts performed spatially arranged choice responses to stimulus locations. The relationship between prime and target locations (congruity) and the mappin g between target and response locations (compatibility) were factorially ma nipulated. Although participants were unaware of prime locations, choice re sponses were faster for congruent than incongruent conditions irrespective of the mapping. visual ERP components and the onset of the lateralized read iness potential (LRP), an index of specific motor activation, revealed that neither perceptual nor preselection processes contributed to the congruity effect. However; the LRP waveform indicated that primes activated response s that fit the stimulus-response mapping. These results support the view th at sensorimotor processing of masked stimuli is functionally distinct Si om their conscious perception.