Colored grating patterns were presented to 8 participants in
a passive oddball condition (standard, 87.5% and deviant, 12.5%,
differing in their color). In the corresponding multicolor
condition, grating patterns of eight different colors were
presented, their probabilities set equal both to each other
and to that of the deviant in the oddball task. Compared with
the ERP response elicited by the standard stimulus, the deviant
response was negatively displaced over posterior areas, the
difference wave peaking at 136 ms. A similar negative wave was
obtained when the ERP response to the deviant was compared with
the ERP elicited by the same stimulus in the multicolor condition.
This result rules out stimulus- (color-) specific refractoriness
as a major factor in the generation of the deviance-related
posterior negativity. The observed posterior negativity can
therefore be regarded as a visual analog of the mismatch negativity
(vMMN).