Wagon wheel effect

While my son was playing with his Legos, he came up with an interesting question. I had thought about this when I was a kid, but never was inquisitive enough to look for an answer. My husband felt the same. We all get occupied with the demands of our education system that we forget to look into the life around us.

The question was" when I rotate this wheel fast, it appears to rotate backwards.Why does it feel so? "

https://www.youtube.com/watch?v=fUoLpcjwgJc

 The answer is quite interesting, It's a beautiful optical illusion. When the wheel rotates at a high speed, there is a mismatch between the image sent and the image processed from our brain. Because of this mismatch, the optical illusion of wheel rotating backward takes place. This phenomenon is called 'Wagon wheel effect'.

Thanks to my son for letting us explore and learn new things. Thanks to Bala anna and Deepak Seshadri for giving additional ideas to explore. 

We observed the optical illusion is minimal or at times there is no illusion at all when there are no grooves on the wheel. We can observe this illusion in our car wheels too.

https://commons.wikimedia.org/wiki/File:The_wagon-wheel_effect.ogv

The wagon-wheel effect (alternatively, stagecoach-wheel effect, stroboscopic effect) is an optical illusion in which a spoked wheel appears to rotate differently from its true rotation. The wheel can appear to rotate more slowly than the true rotation, it can appear stationary, or it can appear to rotate in the opposite direction from the true rotation. This last form of the effect is sometimes called the reverse rotation effect. 

https://en.wikipedia.org/wiki/Wagon-wheel_effect#/media/File:WagonWheelEffect.gif