Reverse Rotation of Car Wheels

Cecil's Columns/Staff Reports
1

First up: sorry no cites.

However, while ingenious, Cecil is open to correction on this point

There, I’ve said it.

Speaking personally, I see reverse rotation all the time, in real life. Yesterday just outside my place for example.

Most interestingly: Why? It is an optical effect, entirely to do with how the mind processes visual information. People do differ in how visual information is processed.

A while ago, I attended a week of seminars on structure/function connectivity in the brain. One experiment was to hold up a large diagram of concentric circles of variegated colour. To some people in the audience, myself included, some of the rings formed appeared to be spinning very fast. Cecil is probably one of the people who would not see it, about 60-70% of my group.

The ‘reverse rotation’ of car wheels is bests explained as the same effect.

On reflection, I may have been too unequivocal here. Nonetheless Cecil’s explanation entirely fails to explain my common experience: Broad daylight; no intervening screen; apparent reverse rotation.

2

I agree, I have noticed the spinning in reverse effect quite often. As I also noticed it on tv I thought everybody had the same experience in real life aswell.

I read somewhere that is because essentially the eye/brain works as a camera. We pick up moving things in frames, quite more than the 25 per second, but still, its not completely fluid. This is also why we have no problem being fooled by tv/movie frames, ect.

3

I also see this reverse roatation? Is this normal?

4

I’ve got a fan on my desk. If I quickly flip it off and on it seems momentarily to spin in reverse.

5

I often see it. In daylight. In person.

Wheels and aircraft propellers mostly.

6

both bicycles and motercycles, in sunlight and street lights

7

why is it always mentioned that the wheel must be slowing down? can’t the wheel be speeding up but only up to a rate that causes it to be seen (by camera shutter or the eye) after 359 degrees or less of rotation, thereby having the appearance of spinning backwards? as the speed increases and the speed gets closer and closer to reaching and passing 360 rotations per [whatever time period, say 24s to assume 24fps camera], wouldn’t the appearance of reverse spinning be in effect and merely get smoother yet appear to be spinning backwards slower and slower until the illusion was destroyed after passing 360 rotations per 24s? if your confused as to what i’m trying to say, imagine the second hand on a clock. look up at the clock every 59 seconds, Oh no! it’s travelling the wrong way…

(actually we don’t need to assume getting spinning 360 times per time-period since wheels look the same and would therefore only need to go 1/5 of a rotation, or whatever fraction, in order to look stationary)

8

Welcome to the forum, Mahou.

Who says the wheel must be slowing down? I don’t think I’ve seen that in any discussion of the phenomenon.

You are perfectly correct in the rest of your post. That’s exactly how the effect works.

9

not that it mentions specifically that it has to be slowing down, but that’s the only thing the original article mentioned. i guess i just assumed too much, sorry.
http://www.straightdope.com/classics/a3_199.html

10

I’ve noticed ‘reverse rotation’ from time to time, usually when there are sodium lights. I’ve also seen it on large trucks with chrome wheels, even in broad daylight. This morning I noticed it on a car (I think it was a Porsche I passed). I looked in the rearview mirror on my motorcycle, which I was riding around 5,000 rpm, and the wheels on the car seemed to stop/strobe although they didn’t actually appear to reverse. I put it down to a very quick look in the rearview mirror (like I got a ‘snapshot’) plus the vibration of the bike.