In a previous article, "Yes - I have a name" said:
I'm sure I've seen wheels on cars that appear to be moving backwards. Are
my
eyes defective?

That's due to something else strobing the light, such as the reflection
off other wheels or off the lugnuts. It's also reported that a steady
vibration of your eyes can cause the effect, such as when humming (or
probably while sitting in a noisy airplane).

http://findarticles.com/p/articles/m...17/ai_18471030

The discrete vision theory has been discredited.

Kline K, Holcombe A, Eagleman D (2004). "Illusory motion reversal is
caused by rivalry, not by perceptual snapshots of the visual field.".
Vision Res 44 (23): 2653-8. PMID 15358060.

Kline K, Holcombe A, Eagleman D (2006). "Illusory motion reversal does not
imply discrete processing: Reply to Rojas et al.". Vision Res 46 (6-7):
1158-9. PMID 16199075

--
Paul Tomblin http://blog.xcski.com/
C is *supposed* to be dangerous, damnit!
-- Anonymous, on "Safer C"