Wagon Wheel Illusion Revisited

Pooya PakarianProgram in Neural computation, CNBC,CMU

Part of:

Pakarian P. (2006) Wagon Wheel illusion Revisited. Perception under review.

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

What this poster is NOT about: Wagon Wheel illusion in Sunlight

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.