Eli5 how when you look at something that has a brighter background for a long time, and you suddenly close your eyes. How does that image get “burned” in your brain for about a minute?

Question

Was looking at my phone near my window and it was quite sunny outside, I suddenly turn around and shut my eyes for a second and the image of my phone and the light from the window was burned into my mind for 30 seconds or so. I’ve seen optical illusions work like that before where you stare at a dot on your computer screen then look around your room. So, how does it work?

In: Biology

Answer 1

Your vision is formed by the excitation of specialized nerve cells on the back on your eyes. When light falls on them, they send a signal to your brain, and your brain assembles the data into an image.

When overly bright light is shone on the cells for an extended period, the cells can get over stimulated, and produce too much of the signal, and keep doing so even after the light has gone. Your brain perceives this as the after image.