Visual mismatch negativity: the detection of stimulus change.

Mismatch negativity is an event related potential generated by a mechanism which detects stimulus change. Such a mechanism is important to enable attention to be switched to important changes in the environment. The effect has been extensively studied in the auditory modality. The present investigation was designed to establish whether the enhanced negativity in the visual event related potential evoked by deviant stimuli presented infrequently among a sequence of repeated standard stimuli is really associated with the detection of stimulus change. The experiment set out to distinguish effects associated with stimulus change from those related to the physical attributes of the stimuli or to differences in the refractory state of receptors or neurons. The findings support the hypothesis that deviance-related negativity reflects the operation of a change detection mechanism and not the refractory state of elements of the visual system.