This is Hidden Brain, I'm Shankar Vidantantham.

Depending on when you were born, you might have a special reaction to some of these socks.

We met I knew I needed you so.

We are the champions of my friends.

This is what it sounds like when your nose cries.

I wanna, I wanna, I wanna, I wanna really, really, really wanna say,

because it's time.

If you wanna be...

Chances are, at least one of those songs evoked a feeling in you, a sort of fuzzy feeling,

maybe a sense of longing.

Maybe a memory popped up in your mind.

Most likely, what you're experiencing is nostalgia.

We take it for granted that nostalgia is an ordinary, harmless emotion.

Nobody thinks you should go to a therapist for posting a photo from your childhood with

the hashtag ThrowbackThursday, or if you have a weak spot for fruit loops or lucky charms.

But that's a relatively new way of thinking.

It started out very much as being considered a disease, and people even today,

a lot of people say, well, I'm not nostalgic because I think about the future.

Today on Hidden Brain, what exactly is nostalgia?

And can nostalgia help us move forward in life, or does it simply leave us stuck in the past?

Clay Rutledge is a psychology professor at Not Dakota State University.

He's the author of Nostalgia, a psychological resource.

...