The Perception of History: Seeing Causal History in Static Shapes Induces Illusory Motion Perception.

The perception of shape, it has been argued, also often entails the perception of time. A cookie missing a bite, for example, is seen as a whole cookie that was subsequently bitten. It has never been clear, however, whether such observations truly reflect visual processing. To explore this possibility, we tested whether the perception of history in static shapes could actually induce illusory motion perception. Observers watched a square change to a truncated form, with a "piece" of it missing, and they reported whether this change was sudden or gradual. When the contours of the missing piece suggested a type of historical "intrusion" (as when one pokes a finger into a lump of clay), observers actually saw that intrusion occur: The change appeared to be gradual even when it was actually sudden, in a type of transformational apparent motion. This provides striking phenomenological evidence that vision involves reconstructing causal history from static shapes.