Wagon Wheel Illusion
Revisited
Pooya Pakarian
Program in Neural computation, CNBC,CMU
Part of:
Pakarian P. (2006) Wagon Wheel illusion Revisited. Perception under review.
What this poster is NOT about: Wagon Wheel illusion in Sunlight
This poster is NOT about the more interesting phenomenon of Wagon
Wheel Illusion under continuous illumination such as sunlight, that is said
to probe the intermittency of human visual perception as discussed in:
Purves D., Paydarfar J.A., and Andrews T.J., 1996. The wagon wheel
illusion in movies and reality. Proc Natl Acad Sci U S A; 93(8):3693-7.
Pakarian P. and Yasamy M.T., 2003. Wagon-wheel illusion under steady
illumination: real or illusory? Perception; 32(11): 1307-10.
Holcombe AO, Clifford CW, Eagleman DM, Pakarian P. Illusory motion
reversal in tune with motion detectors. Trends Cogn Sci.; 9(12):559-60
Proximity Law & Classic WWI in Stroboscopic Light >25 Hz
But this description that is based on Nyquist theorem of signal
processing can not describe what really happens in this illusion.
Visual Persistence: Fusion of Successive Stroboscopic Snapshots
Classic WWI occurs several times under Nyquist limit
motionless
reversed motion
veridical direction
Bistability in the perceived number of spokes and the rotation direction
Two kinds of direction reversal occur:
1- apparent rotation speed declines to
zero and then it is reversed without
change in the number of illusory spokes
1- bistable percpetion between opposite
rotation directions both with maximum
velocity and different number of illusory
spokes.