The change from visible to invisible:

It is argued that the problem of the phenomenal persistence of objects in experience, often called “object permanence,” is actually a problem of the discriminating of persisting from nonpersisting things. A distinction is made between objects that go out of sight and objects that go out of existence, and it is shown that optical information exists to distinguish these two cases. Evidence is provided from a series of motion picture displays to suggest that Os do in fact distinguish them. The various optical transitions are shown to be reversing in the first case, but nonreversing in the second. In particular, the transition that specifies the occlusion of one surface by another is analyzed, together with the inverse of this transition. This study is a sequel to an earlier one of optical transformations.