I stop looking…but my eyes keep on going!

pinwheelWhat keeps our eyes going after we stop looking is something called an after image.

After images work because of the way human light receptors work. Our eyeballs are full of them. If we “bathe” them in light, they take a few seconds to calm down.

As they chill out, they continue to send weak signals to the brain. If we concentrate a little, we can sometimes see the weak signals in our mind’s eye, as after images.