van der Helm’s “Kaleidoscope Motion”
What to do & see
The red cogwheel rotates, but does it rotate smoothely? Physically, the rotation
is perfectly smooth as you can confirm by making parts of the arrangement transparent,
using the vertical sliders left and right. However it seemingly jolts ever so often.
Depending on conditions (contrast to the background, and between the stationary
and rotating part) other percepts arise.
You can select between 3 different presets or adjust colours, transparency, and
motion speed.
Comment
This effect shows that there are still new illusions out there to be discovered
and/or formally described. As Peter van der Helm discusses in his paper (2007),
the effects here are probably caused by colour assimilation and/or ambiguous figure-ground
segregation.
References
van der Helm PA (2007) Kaleidoscopic motion and velocity illusions. Vision Res 47:460–465
[PDF]
Peter
van der Helm’s own demonstration page
Created: 2007-02-25
Last update: 2013-10-04