Horizontal lines appear to tilt.pic.twitter.com/W1YsesHFfY
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The "indirect" effect shows the reversal of the Zöllner illusion. In this image, the vertical line appears to tilt clockwise. Kitaoka, A. and Ishihara, M. (2000). Three elemental illusions determine the Zöllner illusion. Perception & Psychophysics, 62, 569-575.pic.twitter.com/eaU0GAhNac
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