Talk:Wagon-wheel effect
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I think this page should be merged with that for "Reverse_rotation_effect"
I have seen this effect on wheels that are under continuous illumination: Often, when driving slowly past a moving car with shiny alloy wheels, in the adjacent lane on the freeway for example, the spokes appear to be rotating backwards. If you look closely, it looks as thought this illusion is caused by the changing angle of sun rays reflecting from the shiny (often round) spokes. So, what you are actually seeing is the suns reflection slowly counter-rotating, not the spokes themselves. However, because the spokes are in quick motion and under continuous illumintaion, they are blurred and all you can see is the counter-rotating reflection of the sun. Ofcourse, they can be seen rotating either backwards or forwards at a variety of speeds, depending on the speed of the wheel and how fast you drive past it etc. Has anyone else observed this effect? - Sir_Spike
I have noticed this, yes, and can see where you're coming from here. However, I wonder if the fact that you are in a car - that by dint of its engine frequency coupled with the motion of your car over the rod maybe causing your eyeballs to vibrate in their sockets at a high frequency but low amplitude - means that you are subconsciously viewing the other car's wheels auto-stroboscopically.
As a kid I used to race my toy cars, watching the wheels as they went round, under continuous illumination. I've often wondered since why I occasionally experienced the wagon wheel effect when doing so. I now think it was possibly due to my making 'engine' noises which were akin to the humming effect as desribed in the article. Martyn Smith 16:20, 5 July 2006 (UTC)
Yeah, when I hum loudly in front of my CRT monitor, the whole screen appears to wobble and writhe. So I guess that is beleivable. Sir Spike 05:38, 14 June 2007 (UTC)
Actually, perhaps it is just the vibration of the eyeballs alone which is responsible for this effect? Sir Spike 06:59, 19 June 2007 (UTC)
[edit] The lug nut trick
I've seen more than once a reverse-rotation illusion in the lug nuts of large trucks. The effect is easily produced while installing wheels by careful adjustment of the angles of the lug nuts. Since the phenomenon is somewhat common, this technique must be well known to garage mechanics (though I've never encountered it in any literature.) --Wjbeaty 19:02, 14 August 2006 (UTC)
That may be true, but I stress that whenever there are curved reflective surfaces occuring at intervals around the wheels (such as shiny spokes or the curved top of the lug nuts), when there is relative motion between the observer and the spinning wheel, a wagon wheel effect may be witnessed. I imagine that this effect would be more commonly witnessed than your 'carefully oriented' lug nut scenario, and would therefore probably explain the majority of most sightings. Sir Spike 05:46, 14 June 2007 (UTC)
[edit] Health warnings anyone?
There really should be a bigassed caution at the top of this page. It'd be a pity if someone discovered they had epilepsy after trying out some staring experiments they read about on Wikipedia. Jesus H Christ I can't believe I'm the one saying won't someone please think of the children!? 83.70.166.156 03:55, 6 October 2006 (UTC)
Can anybody point to any research suggesting that flickering stimuli on a computer screen are a risk for seizure in people who don't already know that they are vulnerable (i.e. people who know they're epileptic)? I once looked for some research on this but couldn't find any. In any case I don't think any warning should be at the top of this wikipedia page, but rather next to any external link to a flickering stimulus. But again I'm not sure this is much of a concern, for example I believe some research concluded the Japanese cartoon scare was basically hysteria, but I'm not sure.. --Alex Holcombe 11:35, 14 May 2007 (UTC)
[edit] Suggested link
I'd like to suggest a link for this page. I'd add it myself, but the link points to a page and applet on my own website, so it would be better if somebody else looked at it and agreed that it's worth adding (or maybe not agree :-) ) It might be more appropriate for Temporal aliasing though... http://ws.cs.ubc.ca/~sanchom/wiki/index.php/Temporal_Aliasing Sancho 06:57, 14 May 2007 (UTC)
