Reversed visual motion and self-sustaining eye oscillations.
A random-dot field undergoing counterphase flicker paradoxically appears to move in the same direction as head and eye movements, i.e. opposite to the optic-flow field. The effect is robust and occurs over a wide range of flicker rates and pixel sizes. The phenomenon can be explained by reversed phi motion caused by apparent pixel movement between successive retinal images. The reversed motion provides a positive feedback control of the display, whereas under normal conditions retinal signals provide a negative feedback. This altered polarity invokes self-sustaining eye movements akin to involuntary optokinetic nystagmus.
Spillmann
L
L
Institute of Biophysics, University of Freiburg, Germany. spillman@ruf.uni-freiburg.de
Anstis
S
S
Kurtenbach
A
A
Howard
I
I
D005133:Eye Movements; D005246:Feedback; D005366:Figural Aftereffect; D006801:Humans; D009903:Optical Illusions