A variant of the anomalous motion illusion based upon contrast and visual latency.
We examined a variant of the anomalous motion illusion. In a series of experiments, we ascertained luminance contrast to be the critical factor. Low-contrast random dots showed longer latency than high-contrast ones, irrespective of whether they were dark or light (experiments 1 -3). We conjecture that this illusion may share the same mechanism with the Hess effect, which is characterised by visual delay of a low-contrast, dark stimulus in a moving situation. Since the Hess effect is known as the monocular version of the Pulfrich effect, we examined whether illusory motion in depth could be observed if a high-contrast pattern was projected to one eye and the same pattern of low-contrast was presented to the other eye, and they were binocularly fused and swayed horizontally. Observers then reported illusory motion in depth when the low-contrast pattern was dark, but they did not when it was bright (experiment 4). Possible explanations of this inconsistency are discussed.
Kitaoka
Akiyoshi
A
Department of Psychology, Ritsumeikan University, 56-1 Tojiin Kitamachi, Kita-ku, Kyoto 603-8577, Japan. akitaoka@lt.ritsumei.ac.jp
Ashida
Hiroshi
H
D015350:Contrast Sensitivity; D003623:Dark Adaptation; D003867:Depth Perception; D006801:Humans; D008027:Light; D009039:Motion Perception; D009903:Optical Illusions; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D011930:Reaction Time; D015348:Vision, Binocular