Two interesting illusions based on anomalous perception or interpretation of motion. Notice the two wave forms in the image above. When you click on the image you will be taken to a page where the two sinusoidal waves are in motion to the left. But notice, that the eye/brain seems to perceive the translational motion without trouble for the right-hand wave of large amplitude, yet in the left-hand case the object is (for most of us) perceived as a flexible rod which is translationally at rest but is wiggling up and down as if made of jello. The page contains an explanation of why the perceptions of the wave motion are so different in left-hand versus right-hand cases, low-amplitude versus high-amplitude waves. I find that if I follow the left-hand wave with my eyes, the illusion vanishes and a travelling wave is perceived, but if I fix my attention on the center of the pattern, the illusion of a stationary object wobbling is strong.

Equally fascinating is what I call the "highway" illusion, shown above. Clicking on the image will take you to a page where the grid-like patterns are in motion. Fix your attention on the tiny black square in the upper-right half of the rectangle and try to decide how the tiny grey squares inside the white grid are moving. You will be surprised! Now do the same with the tiny black square in the lower-left corner, and again try to decide how the tiny grey squares are moving within the white grid. The interpretation is totally different, yet the entire image is just being translated along the diagonal uniformly! An explanation will be found on the page, as well as links to some other remarkable illusions. I see vertical motion in the upper-right "highway vehicles," and horizontal motion in the lower-left "vehicles." What about you?