Stop-and-go illusions: The effects of attention and motion signals on motion perception
Date Issued
2009
Date
2009
Author(s)
Chiu, Chien-Hui
Abstract
In the footsteps illusion (Anstis, 2001), motion speeds up at high contrasts and slows down at low contrasts, coming to a complete halt at equiluminance. Such speed change has been attributed to low-level contrast-dependent mechanisms, with motion signals completely absent at equiluminance. However, a seemingly similar illusion that also shows the “stopping” illusion, the fan illusion, has been shown to be affected by attention (Yeh, Chiu, & Hsiao, 2007). To link the footsteps illusions with the fan illusion, we demonstrated that in the presence and absence of motion signals, both the footsteps and fan illusions are similarly affected by contrast (Experiment 1and 2), but in ways that are inconsistent with previous explanations (Howe, Thompson, Anstis, Sagreiya, & Livingstone, 2006). In Experiment 3, we further showed that manipulation of attentive tracking influenced illusion strength. We conclude that both contrast-dependent motion perception and attentive tracking determine perceived speed in the two illusions.
Subjects
contrast
motion
tracking
footsteps illusion
fan illusion
attention
occlusion
perceived speed
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