Changes in illumination color induce powerful illusory rotations

We present a novel, to the best of our knowledge, interactive mechanism for inducing illusory rotations. Printed versions of Kitaoka's rotating snakes illusion change effective color contrast depending on LED illumination color. This drives changes in the illusory rotations. In a psychophysical experiment, participants indicated by button press whether they perceived a given pattern to rotate as the color of illumination changed and in which direction this rotation occurred. Results could be predicted by an effective luminance contrast model, and we found high agreement between observers. This constitutes a novel manner of showing perceptual mechanisms, allowing for new applications and adding perceptual dynamics to static imagery.