Electrophysiological correlates of stimulus processing in change blindness.

Change blindness--the inability to detect salient changes when a distractor event occurs simultaneously--has been repeatedly used to investigate the neural correlates of awareness. The fact that the N2pc, which is basically assigned to attention processing, has been observed only for detected changes in such tasks lead to the assumption that this component may also reflect awareness. In contrast to previous electrophysiological studies, we used mudsplashes (experiment 1) or a very short blank (experiment 2) to induce change blindness so that the change was not occluded. A change, regardless of its detection, elicited a reliable N2pc. Successful change detection, however, was reflected in an enhanced amplitude of the N2pc component. Thus, the N2pc cannot be taken as a direct correlate of awareness but rather as a marker for a process that is necessary but not sufficient for awareness. Taking into account the generation of the N2pc in extrastriate visual areas, this finding fits nicely with the recent discussion about reentrant processing as a basis for visual awareness.