Stare at this for a while and you'll be able to transfer the effect off your screen.
What: This optical illusion (though im not entirely sure it falls into the illusion category) demonstrates an effect that occurs when you observe a moving pattern for a certain amount of time, and then begin looking at something else. This can occur naturally in nature, such as looking at a waterfall and then observing the cliffs beside it.
I have also coded up another version of this similar effect A similar effect on this site! Using straight lines rather than a spiral.
How To: In this example, you need to stare into the center of the spirals, which are turning into a single direction, with an outer spinning the other way. After around twenty to thirty seconds you can look away, ideally at some art on the wall, outside, or your hands and you will see an inverse motion happening.
Explain It: This is another one that comes down to how your neurons process data, something I don’t understand too well, but am happy to quote.
Neurons coding a particular movement reduce their responses with time of exposure to a constantly moving stimulus; this is neural adaptation
One theory is that perception of stationary objects—for example, rocks beside a waterfall—is coded as the balance among the baseline responses of neurons coding all possible directions of motion.
I've researched these illusions in my spare time but am clearly not any kind of expert and my explainations are pretty smooth brained, if you find something mis-cited, earlier examples, or general mistakes please new let me know via email@example.com, be kind!