The horizontal bar appears and disappears all at once, yet most observers
see it growing out from the lefthand side - the small notch visible in the
first frame is sufficient to impose this organisation on the display.
In simple apparent motion displays, the shape of the moving object remains constant from frame to frame in the animation sequence. In transformational apparent motion displays, the shape changes during its motion, and this shape change presents the visual system with a problem - how does it match up the differing shapes from frame to frame? The movement that is perceived reflects the solution. Tse et al. (1998) demonstrate that geometrical properties such as contiguity, contour smoothness, and occlusion constrain the solution in very systematic ways.
The display above contains only these two animation frames: The horizontal bar appears and disappears all at once, yet most observers
see it growing out from the lefthand side - the small notch visible in the
first frame is sufficient to impose this organisation on the display.