“I” is one of the most common words in the English language, something experts have often thought was the result of the human desire for trust and intimacy. But a new study says the main reason we talk about ourselves so much is simply because our brains like it.

Harvard University researchers used brain scans during a series of recent experiments to learn how much people liked talking about themselves and why.

No matter the test, the results were the same: self-disclosure has a biological payoff. The researchers found that sharing personal information led to activity in the same reward areas of the brain that respond to sex and food, while talking about other people didn’t have the same effect.

And when the participants knew they had an audience for their self-directed conversation, their brains’ reward centers lit up even more — which could explain much of the appeal of social media sites like Facebook and Twitter.

[Time]