Masking unveils pre-amodal completion representation in visual search

Abstract

When one object is partly occluded by another, its occluded parts are perceptually 'filled in', that is, the occluded object appears to continue behind its occluder. This process is known as amodal completion. The completion of a partially occluded object takes about 200 ms, and pre-completion information (that is, information from before amodal completion has occurred) exists in the visual system for that duration. It has been suggested, however, that observers cannot make use of this information, even when it is beneficial to do so: visual search for a target that appears to be partly occluded, for example, is slower than for a target that does not undergo occlusion, despite both targets being physically identical. Here we show that visual search does have access to pre-completion representations, but only for a limited time that depends on the size of the occluded region.