A new motion illusion.
Two instances of a new illusion of motion were discovered. In the first, when observers tracked a spot of light moving vertically in a field of stationary vertical lines, the lines appeared to move in the same direction as the spot. If observers did not track the spot, the lines appeared stationary. The second instance was designed to see if the same illusion would occur when the spot appeared to move as a result of induced motion. In this display a vertically moving grid of horizontal lines surrounded a stationary vertical line. A stationary spot of light could be projected on the line. If the subject fixated the spot, both spot and line appeared to move against the grid. If the spot was absent, the line appeared to move along with the grid. The implications of this illusion for theories of induced motion are discussed.
D005403:Fixation, Ocular; D005556:Form Perception; D006801:Humans; D007088:Illusions; D009039:Motion Perception; D009903:Optical Illusions; D009949:Orientation