When you watch a car commercial, have you ever noticed that sometimes the wheels seem to turn backwards?

Or sometimes you see a video of a helicopter and it seems like the blades are barely turning.

But you never see that in real life, so what's going on there? And what does this have to do with yellow street lamps?

Or whether all four legs of a horse come off the ground when it runs?

Or the very surprising thing that happens if you stare and stare at your ceiling fan while it turns.

Welcome to Inner Cosmos with me, David Eagleman.

I'm a neuroscientist and author at Stanford.

And in these episodes, we sail deeply into our three-pound universe to understand why and how

our lives look the way they do. And in this case, why the world

looks the way it does. Today's episode is about visual perception and a series of really

strange surprises about whether our visual systems analyze the

world continuously or instead whether we see in frames like a movie camera. So, have you ever

noticed what happens when you film a car going by on your cell phone camera and then you watch the video?

When you look at the hubcaps on the car, say with some spokes on it or some pattern, when you look at the hubcaps, it looks like they're spinning the wrong way.

Or maybe they occasionally look like they're not spinning at all even though the car is moving.

So the first question is, why do we so rarely notice this? Like why doesn't it blow our minds and we

say, oh my God, that's not consistent with what I just saw with my own eyes and what I filmed?

Why is it that we're so nonchalant about that?

I'll be addressing that in some future episodes.

But today, the main question I want to ask is,

why does it happen?

Why does the wheel look on your video

...