Abstract
An event-related brain potential component called visual mismatch negativity (MMN) reflects the automatic processing of rule-violating events embedded in a visual stimulus sequence. To investigate whether or not the processing of rule-violating events in a task-irrelevant stimulus sequence can be affected by top-down control, we examined the effects of the participant's voluntary action on visual MMN with a dual-task design. As a primary task, the participants were required to detect a sudden size-change of a central fixation point. As a secondary task, they were required to press one button frequently (about 90%) and another button infrequently (10%) in random order, which produced a task-irrelevant stimulus sequence at surrounding locations. Frequently-performed button presses triggered rule-conforming stimuli (81%), but occasionally rule-violating stimuli (9%, externally-generated rule violation). In contrast, infrequently-performed button presses triggered rule-violating stimuli (9%, self-generated rule violation), but occasionally rule-conforming stimuli (1%). Visual MMN was elicited by externally-generated rule violation, but not by self-generated rule violation. This result indicates that the processing of rule-violating events in a task-irrelevant stimulus sequence can be modulated by top-down control.
