Attention, Perception, & Psychophysics

, Volume 74, Issue 6, pp 1343-1354

First online:

Sensitivity of event-related brain potentials to task rules

  • S. NasrAffiliated withSchool of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM)Research Center for Brain and Cognitive Sciences, School of Medicine, Shaheed Beheshti UniversityAthinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Email author 


Previous studies have suggested that brain potentials evoked around 300 ms after stimulus onset index the processes underlying perceptual decision-making. However, the sensitivity of these evoked potentials to the task rules, which link sensory perception to the proper action, has not been studied previously. In this study, event-related potentials (ERPs) of the human brain were examined when subjects randomly performed delayed-matching-to-identity (DMI) and delayed-matching-to-category (DMC) tasks. The results showed that the amplitudes of the brain potentials evoked 228–328 ms after test-stimulus onset varied according to the task rules and indexed the processes responsible for decision-making. In contrast to these potentials, the preceding evoked activity (< 228 ms) did not show any sensitivity to the changes in the subjects’ responses and indexed the processes responsible for stimulus perception. These findings support the idea that the potentials evoked after 228 ms from stimulus onset are influenced by the task rules and do not index simple sensory perception.


Decision-making Object Recognition Perceptual categorization and identification Sensory perception Visual matching