A puzzling percept of stimulus stabilization.

A visual illusion is reported which comprises the following: when a monitor with a moving constant velocity grating is swayed in front of a subject, the grating may be perceived as freezing or decelerating on the screen. This percept appears to depend on the magnitude and direction of the retinal grating velocity, relative to that of the monitor. Various possible explanations are rejected. It is concluded that the illusion shows a resemblance to the phenomenon of "motion capture" but that it has certain new characteristics that require an explanation.