STOPPED CLOCK ILLUSION

Hey, Vsauce. Michael here.

And today I've got a brand new episode of Vsauce Leanback. You can click this annotation or the link at the top of the description to start it, and then you can just lean back and the autoplay playlist will bring the knowledge right to your brain. As you already know, it doesn't really work on mobile phones yet, so wait until you are in a better position to lean back.

In the meantime, let's get saccadic. No, not psychotic; saccadic, referring to what is known as a saccade—the quick movements that our eyeballs make when we move from one object to the other. As you may remember from a previous Leanback, some animals, like most birds, cannot move their eyeballs.

And so, to look from one thing to another, they have to move their head really, really fast. To keep the world from being blurry when their bodies move, they have to keep their heads completely stationary. But here's the neat thing about saccades. When our eyes move, there's a quick blur between one destination and the other.

And that blur is completely incomprehensible to our brain. So what our visual system does is erase it from our memory and instead replace that little fraction of a second that our eye moved during with the very next thing we see. This leads to a really amazing illusion called 'The Stopped Clock Illusion.'

You may have noticed this before if you've ever been in a room with a clock with a second hand, like in a classroom, darting your eyes back and forth, waiting for class to be out. Now here is what happens. Right when you dart your eyes to the clock, that very first second—that very first movement of the second hand that happens when your eyes reach it—seems longer than every other second afterwards.

Look away from the clock and then look. And that first second will seem to linger, as if time itself has stopped. The reason for that is that your brain replaces the time it took for your eye to go from here to the clock with an image of the first thing you saw, which was the second hand.

And so, that little fraction of a second of time is added to the length of time it takes the second hand to move. What's really mind-blowing about this entire effect is that it happens all the time. All day, as you look around the world from one point to another, that little fraction of a second that your eyeball was moving is lost, and your brain just replaces it with the very next thing that you see.

Now, it might just be a tiny, tiny amount of time, but over the course of an entire day, those little fractions of a second add up to almost 40 minutes. 40 minutes of every day that you're awake are lost because our eyeballs move.

And as always, thanks for watching. So what are you waiting for? Click here to start the Leanback or click the link at the top of this video's description. You know what? I totally never say this... Yeah, I'm totally heterosexual, but... You are really attractive!