When you close your eyes, and push on the side of either eyelid, you see a dark spot appear in your vision on the opposite side of the area that you’re applying pressure to. Why is that?
In: Biology
Essentially, the primary or “true” stimulus for the receptor cells in the back of your eyes is light, but they can still perceive other things as well, such as the pressure from your finger pushing on the front/side of the eye. This causes them to report a biochemical signal that is similar to how they report light to the brain, and it’s interpreted as such. This kind of “wrong” signalling can happen via other senses as well.
Edit: also, the reason the dark spot occurs opposite from where you press with your finger is because those receptor cells are in the *back* of the eye. If you push on the right side of your eye, you “see” the spot on the left side, because you are stimulating the cells on the back-right side of the eye that would normally catch light entering the eye *from the left*. The brain then translates it exactly like that.
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