The Ouchi Illusion DEMOs

* If you do not see the figure, you need a Java plug-in.

The Ouchi illusion

If you loosely gaze at the central disk, it appears to float apart. Either your eye movement or the physical figure movement can cause the same effect. Therefore, to have a more constant effect, print this picture file on a paper and sway it slowly back and forth in a diagonal direction.

Adjust the length and the width to make more square checkers, to see how the difference of rectangle orientation is essential. Increasing the gap helps segmentation for squares.

Spatial tuning of the illusion

First, adjust "rect. lenghth" and "rect. width" so that you see maximum illusory motion in this figure. Then, change the disk size ("radius") to about a half size. Does the rectangle size remain optimal? Or do you need to make smaller rectangles to have a nice effect?

The effect of random shifting

First, adjust "bar width" to make thin black bars. I hope the illusion does not change a lot. Then, increase "rnd shift" to randomly shift each bar. Isn't the illusory motion weakend or abolished? You can also test that introducing a small gap does not have a serious effect.

This reduction of illusion is closely related to the decrease of the amplitude of the Fourier fundamental components.

Minimum References

Ashida (2002). Vision Research, 42, 1413-
Ashida, Kitaoka, & Sakurai (2002, ECVP).
Ashida, Kitaoka, & Sakurai, submitted to Perception.


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