If the brain can “fill” the gap when we move our eyes, like the “longer second” phenomenon, can it be the source of weird stuff we think we see sometimes for a split second?

Question

Like when you feel you saw something pass by for a fraction of a second, or an unfamiliar person looking like someone you know for a split second.
Thanks!

In: 138

Answer 1

the most important thing to remember about this is that you’re not actually seeing with your eyes at all. You “see” with your brain, the eyes are just there to catch light.

In biology terms, the brain is a very very expensive thing to run. It takes a lot of energy to run all the the things your brain is doing. This is why brains evolved to also be very efficient, lazy organs. Every corner that can be cut without too much risk will be cut.

One main method the brain uses to cut corners is to relay on past experience. A funny story is how I see cats everywhere. I grew up in a house with many cats, in a neighborhood with many cats so my brain’s past experience says that a neutral color lump on a surface is likely a cat. For a very long time after moving out, I kept seeing “cats” for a split second all over my cat-free apartment. My brain would perceive a shadow, a towel, a bag and go “don’t bother processing, that’s a cat.”
People very often see what they knowingly or *un*knowingly expect to see, even in situations more serious and less funny than phantom cats.

Another aspect of this is that the brain is also a very careful system – it’s meant to keep you alive. This is why movement catches our attention, to the point where other processes literally slow down when something moves in your field of view. Perceiving a tiny movement or flicker of light as something passing is a much better ‘stay alive’ gamble than thinking whatever’s in the bush wanting to bite you isn’t there, and your brain absolutely does not have the budget to pay full attention every time anything moves.

These shortcuts happen all the time, and they happen with all senses. Often, you won’t even notice them. It’s only when those shortcuts clash with reality too badly that you notice that stranger isn’t your friend or you misheard someone. It shows how amazing our brains are at handling a really complex world, but it also means that when you care about something, you have to force your brain to make the effort and really look.