Wave Spiral Illusion

by Jonah Kagan

made with processing.js

Press the spacebar to change whether or not the circles appear to rotate in the same direction or in alternating directions.

What's Going On

This illusion was an attempt to turn the cafe wave illusion into a spiral illusion, since 3-element tilt illusions generally have corresponding spiral illusions. However, in order to create a spiral, each gray circle line has to be tilted in the same direction. The illusory tilt in the cafe wave illusion appeared between two rows of arcs that pointed in the opposite direction. Thus, there was no effective way to create a series of tilted circles that all tilted in the same direction. When the arcs all point in the same direction, the tilt disappears.

Since there is still an incredibly strong motion illusion, I thought the attempt was still worth posting. Note how the motion is in the opposite direction as the arcs, further proving either the strength of the motion effect, or the weakness of the bias stemming from the arc orientation.