Change blindness occurs when the presentation of successively presented pictures goes along with a simultaneous presentation of distractors (e.g., mudsplashes). An ERP component (N2pc) was used to track shifts of attention to lateralized changes under different attentional conditions. Observing central changes and not knowing about lateral changes elicited no N2pc. If lateral changes were task relevant, however, an N2pc was observed for both detected and undetected changes. Repeating the first task, lateral changes also evoked an N2pc, although they were again not task relevant. These results indicate that the transient of the change, although never occluded by mudsplashes, did not attract attention (bottom up) automatically but additional knowledge about its occurrence is necessary (top down). An attentional shift, however, does not necessarily lead to an aware representation of the change.