Event-related potentials during preattentional processing of color stimuli.

To investigate whether visual mismatch negativity (VMMN) could be evoked in the preattentional condition, we designed an oddball task with different red color stimuli in visual modality. Electroencephalograms were recorded and VMMN and N2-P3 complex waveforms were analyzed. The results indicated that VMMN generated at occipital region with 110-180 ms peak latency, and N2b and P3a were just following VMMN with 170-300 and 400-450 ms latencies, respectively. VMMN, N2b, and P3a components were all affected by the amount of deviations between the standard stimuli and deviant stimuli. This study further proved that VMMN existed under hard detection condition in color-related visual modality, and this design distinguished early sensory processing and late sensory processing successfully as well.