Illusory displacement due to object substitution near the consciousness threshold.

A briefly presented target shape can be made invisible by the subsequent presentation of a mask that replaces the target. While varying the target-mask interval in order to investigate perception near the consciousness threshold, we discovered a novel visual illusion. At some intervals, the target is clearly visible, but its location is misperceived. By manipulating the mask's size and target's position, we demonstrate that the perceived target location is always displaced to the boundary of a virtual surface defined by the mask contours. Thus, mutual exclusion of surfaces appears as a cause of masking.