This is Hidden Brain, I'm Shankar Vedantam.

It's almost that time...

...for the Olympics.

The pageantry, the dreams, breathtaking victories...

...for fans, it's an event of extraordinary drama.

Athletes from across the globe competing at the very highest level...

...at the limits of human endurance.

Social scientists find the games equally compelling...

...for what they reveal about human behavior.

When a match ends, the winners and losers do something.

That's immediate, automatic, it's unconscious, they have no control of it, it just happens.

About a second later, then they come to their senses...

...and they realize that they're on stage.

And whatever rules they've learned to manage their expressions kick in then.

Coming up, what the Olympics can teach us about human behavior from a professor...

...who's also an Olympic judo coach.

Stay with us.

My guest today is David Matsumoto.

He's a professor of psychology at San Francisco State University.

He's used the Olympics as a laboratory for psychological observations.

But he's also been a part of the Olympics.

David's coach, the US Olympic judo team and his daughter...

...