to see if this woman, would stand up at the sound of this tone, simply because everyone else is.

You might be thinking you'd never go along with this, or would you?

After just three beeps, and without knowing why she's doing it,

this woman is now conforming perfectly to the group.

But what happens if we take the group away?

Elaine, please.

Okay. Now she's alone. The crowd is gone and nobody is watching her

except our hidden cameras.

What do you think she'll do?

She's now conforming to the rules of the group without them even being there.

Now, watch what happens when we introduce another outsider who doesn't know the rules.

Have a seat and they'll be out in just a couple of minutes. Thanks so much.

Why are you standing up?

Everybody was doing it, so I thought I was supposed to.

Think she'll teach the new guy what to do?

We kept the cameras rolling as more unsuspecting patients arrived.

And slowly but surely, what began as a random rule for this woman

has now become the social norm for everyone in this waiting room.

Here to explain what's going on in their brains is Jonah Berger of the University of Pennsylvania.

This sort of internalized form of her behavior is part of what we call social learning.

Starting at a very early age, when we see members of our group perform a task,

our brains literally reward us for following their footsteps.

When I saw everybody stand up, I felt like I needed to join them,

otherwise I'm like excluded.

Once I decided to go with it, then I felt much more comfortable.

Conformity is how we become socialized, but it can also cause us to develop bad habits or repeat past wrongs.

And it's why even this rebel, who wasn't standing for any of this nonsense, eventually joined the ranks.

And the only thing more shocking than seeing how easily conformity affects the way you act,

is that similar forces are subconsciously shaping the way you think right now.