Induced rotary motion and ocular torsion.
When a large patterned annulus rotates around a stationary sectored disc the latter appears to rotate in the opposite direction. Such induced rotary motion was examined with central discs subtending 5, 20 and 40 deg at the eye, with the surround filling the remainder of the visual field. The annular surround or the central disc could be oscillated sinusoidally around the fixation point through 20 deg at 0.2 Hz. In each case, subjects estimated the angles through which the moving and stationary parts of the display appeared to rotate on one half-cycle. Subjects also estimated the angle of rotation of an oscillating display that filled the visual field. Induced rotation of the centre was around 100% of the inducing amplitude for all disc sizes, but there was no induced motion of the surround when the centre rotated. Ocular torsion was measured under the same conditions, using the scleral search-coil technique. The amplitude of ocular torsion was a function of the size of the stationary or rotating field. Thus, variations in stimulus conditions affected induced rotary motion and ocular torsion in different ways. The implications of the results for theories of induced motion in terms of underregistered eye movements are discussed.
Wade
N J
NJ
Department of Psychology, University of Dundee, Scotland.
Swanston
M T
MT
Howard
I P
IP
Ono
H
H
Shen
X
X
D005133:Eye Movements / Q000502:physiology*; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D009760:Nystagmus, Physiologic / Q000502:physiology; D012399:Rotation