Used in a special projector to test the optokinetic response. The optokinetic reponse allows the eyes to stabilize the image on the retina when the entire visual field is moving continuously (as opposed to a single object), e.g., when looking out the window of a car. The eyes follow the moving field, then snap back (saccade) and start tracking smoothly again.

The device does not actually produce frame-based animation; the film advances smoothly with no shutter, thus projecting an image that is actually moving across the subject's field of view.