Detection of Rst and Second Order Motion

A model of motion detection is presented. The model contains three stages. The rst stage is unoriented and is selective for contrast polarities. The next two stages work in parallel. A phase insensitive stage pools across diierent contrast polarities through a spatiotemporal lter and thus can detect rst and second order motion. A phase sensitive stage keeps contrast polarities separate, each of which is ltered through a spatiotemporal lter, and thus only rst order motion can be detected. Diierential phase sensitivity can therefore account for the detection of rst and second order motion. Phase insensitive detectors correspond to cortical complex cells, and phase sensitive detectors to simple cells.