Illusory rebound motion and the motion continuity heuristic.

A new motion illusion, "illusory rebound motion" (IRM), is described. IRM is qualitatively similar to illusory line motion (ILM). ILM occurs when a bar is presented shortly after an initial stimulus such that the bar appears to move continuously away from the initial stimulus. IRM occurs when a second bar of a different color is presented at the same location as the first bar within a certain delay after ILM, making this second bar appear to move in the opposite direction relative to the preceding direction of ILM. Three plausible accounts of IRM are considered: a shifting attentional gradient model, a motion aftereffect (MAE) model, and a heuristic model. Results imply that IRM arises because of a heuristic about how objects move in the environment: In the absence of countervailing evidence, motion trajectories are assumed to continue away from the location where an object was last seen to move.