Remember those "spot the difference" games you probably played as a kid?
The ones where there'd be two images that looked nearly identical, but had a few details that were different? In fact, I wonder why those little details were so hard to detect?
The reason it's so hard is because the human brain didn't evolve to notice every little detail when we see something. That's especially true when we try to see minute differences in pictures where most of the details are the same. Psychologists call this "change blindness."
Detail-Oriented People Lived Longer
It sounds counterintuitive. Our prehistoric ancestors out on the African savannah probably needed to be really detail-oriented to survive. It's easy to assume that our brains would evolve specifically to notice little details.
But consider our prehistoric ancestors' lives. They had to be on the hunt, doing and finding whatever it takes to eat enough to survive. And they also had to be alert to potential predators.
Most Important Things
That's a lot! It means that our ancestors had to be able to focus only on the most important things. So, the way our brains work is still in line with how theirs worked.
In order to focus our attention, our brains sort of ignore details it registers as unimportant.
So, when we look at those "spot the difference" pictures, we're just not wired to immediately note every single thing. Which is why the little differences are usually in the background and are harder for us to spot.
Thank you to Dan Simons of University of Illinois for reviewing this episode's script.