How Your Brain Decides What You’re Seeing
Your brain makes most of its decisions without bothering to consult with you. Some are trivial: If you had to decide which foot to put down first each and every time you started walking somewhere, you’d be mentally exhausted. So your brain (and body) decide for you, and off you go.
Some of these decisions are not so trivial. You’re moving through some long grass in India when you suddenly freeze. Your brain gibbers the word “tiger,” and then starts the internal alarm: “Awoogah! Awoogah! Awoogah!” It does that after you freeze. Your brain decided it saw a tiger because it added up all the bits of evidence from your eyes and ears and decided: That’s a tiger. And it made you stop to do something about it.
Many decisions require you to weigh the evidence for different options before you can make a choice. Is that a tiger or isn’t it? Do I want the burger or the hot dog? Is that a canoe in your pocket or another item of fiberglass sporting equipment? Your brain seems to solve this beautifully and silently: Without you knowing it, your neurons add up evidence, work out the best option, and tell you how to act.
How do we know this? In the lab, we’re not allowed to lock you in with a live tiger and some long grass. (“Did you see the tiger?” “No, I’ve always had half my arm missing, genius.”) Instead, we show you some dots. Not…
