People devote 30 to 40 percent of their total speaking time to describing their own opinions or experiences, according to much research. A new study suggests that self-expression is intrinsically rewarding, in the same way that sex or eating is. In fact, we find talking about ourselves so pleasurable that we will give up money to do so, as reported in the May 22 Proceedings of the National Academy of Sciences USA.

Diana Tamir and Jason Mitchell of Harvard University used functional MRI to study 195 volunteers between the ages of 18 and 27. They found that when the subjects talked about their opinions or their own personality, the pathways of the brain that register reward—known as the mesolimbic dopamine system—were far more active than when they judged the opinions or personalities of others.

In another experiment, participants were asked to choose several questions to answer from three categories: an inquiry about their own likes and dislikes, an invitation to guess about President Barack Obama's likes and dislikes, or a factual trivia question. The subjects earned between a penny and four cents a question, depending on the category. Although the subjects could have consistently chosen questions to maximize their profit, they preferred to answer the personal queries, forfeiting 54 to 63 cents per trial to talk about themselves.

The findings do not mean we are self-absorbed egotists, the researchers say. Telling others about ourselves helps to bring us together. “One of the ultimate functions of this behavior is social cohesion,” Tamir says.