Visual Illusions of Movement

PAGE1.It i s shown that these illusions are related to involuntary eye movements, occurring either spontaneously as i n the autokinetic illusion, or i n response to the special stimuli associated with the other two illusions.2. During fixation the visual sensation o f movement seems to be produced by, or related to, the pattern o f efferent activity aimed at the group of extraocular muscles which w i l l act as antagonists to the involuntary eye movement referred to.3. Under certain circumstances, when the stimulus change i s rapid, an eye movement may be detected before the fixation reflex has time to operate. 4.Since the sensation can be caused by the pattern o f antagonist efferent activity, i t can arise during fixation with no demonstrable responsible eye movement. .The displacements of a visual after-image,as a result o f the involuntary eye movements, are predominantly i n the direction of agonist activity.ii