[A study of information processing of cognitive conflict using event-related potentials]

This study examined whether cognitive conflict, reported by Eriksen and Eriksen (1974), could be explained by a model of reciprocal inhibition between correct and incorrect response preparation. Subjects responded selectively to a central target letter with flanking compatible (e.g., HHHHH) or incompatible (e.g., SSHSS) noise letters. In the mixed condition all four stimuli were mixed randomly in a block, and in the blocked condition only two stimuli with identical noises were used. The results showed that the reaction times to incompatible stimuli were delayed in the mixed condition compared with that to compatible stimuli, while the delay was significantly reduced in the blocked condition. This blocking effect was also shown on P3 latencies, an event-related potential measure of stimulus evaluation, but not on lateralized readiness potentials (LRPs), a measure of response preparation. Furthermore, irrespective of blocked/mixed conditions, LRPs indicating incorrect preparation were observed. These findings suggest that cognitive conflict could not be explained by the reciprocal inhibition model based on response preparation, but by a model based on stimulus evaluation.