Boundaries of Visual Motion

A representation of visual motion convenient for recognition should make prominent the qualitative differences among simple motions. We argue that the first stage in such a motion representation is to make explicit boundaries that we define as starts, stops, and force discontinuities. When one of these boundaries occurs in motion, human observers have the subjective impression that some fleeting, significant event has occurred. We go farther and hypothesize that one of the subjective motion boundaries is seen if and only if one of our defined boundaries occurs. We enumerate all possible motion boundaries and provide evidence that they are psychologically real.