Photo: AP

Even if you’ve never seen the 1984 film Places in the Heart, in which actress Sally Field portrayed a 1930s southern widow trying to keep her farm out of foreclosure, you no doubt are familiar with Field’s acceptance speech for the Academy Award the role won her. “You like me,” she declared. “You really like me.” With the strong emphasis on the word really, it’s a classic example of the adulation that actors crave.

There are two errors in the previous paragraph, one more important than the other. The minor error: Sally Field did not actually say this line in her acceptance speech. The real line in her speech was, “I can’t deny the fact that you like me, right now, you like me.” We probably misremember the quote because of the other, more important error. It isn’t just actors who are primarily motivated by being liked; we all are. The misquote is so sticky because it exemplifies a central human need.

We all have a need to belong. Signs that others like, admire and love us are central to our well-being. But until very recently, we had no idea how the brain responds to these signs. Recent neuroimaging has changed that.

Perhaps the most dramatic positive sign that we can get from another person — short of a marriage proposal — is to read something that person has written to express their deep affection for us. In a recent study, researchers asked participants’ friends, family members and significant others to compose two letters: one that contained unemotional statements of fact (“You have brown hair”) and one that expressed their positive emotional feelings for the participant (“You are the only person who has ever cared for me more than for yourself”).

Subjects would then lie in an MRI scanner while reading these letters written about them by several of the people they cared about the most. Our intuitive theories suggest there is something radically different about the kind of pleasure that comes from people saying nice things about us and the pleasure that comes from eating a scoop of our favorite ice cream. The former is intangible, both literally and figuratively, while the latter floods our senses. Although there are surely differences between physical and verbal sweets, this study suggested that the brain’s reward system seems to treat these experiences more similarly than we might expect. Being the object of such touching statements activates the ventral striatum in the same way that the other basic rewards in life — like ice cream — do.

In a follow up study, Elizabeth Castle and I looked at how rewarding these touching statements really were. We asked a group of individuals to bid money to try to win these statements. In the end, a large proportion of the participants were willing to give back their entire payment for the study, just to get to see those special words. We may give lip service to the power of money, but the power of knowing we are loved can be just as potent.

It is easy to imagine our reactions to getting this rarely shared positive feedback from the opeople who matter most to us, but would social feedback from complete strangers have the same effect? Surprisingly, yes. Imagine Penelope, a 12-year-old, lying in a scanner watching as a series of faces of other kids appears on a screen. Penelope has never met any of the people she is seeing, but she is informed after seeing each face whether that person wanted to have an online chat with her. Participants like Penelope showed increased activity in the brain’s reward system when finding out that those strangers wanted to have an online chat with them.

These findings were remarkable for two reasons. First, the feedback was ostensibly from complete strangers who had seen the participant’s picture and knew very little else about him or her. Second, the positive feedback led to reward activity even when the participants had no interest in having a chat with the other person. So even strangers we don’t want to interact with activate the brain’s reward system when they tell us they like us.

Other studies have suggested that our brains crave the positive evaluation of others almost to an embarrassing degree. Keise Izuma conducted a study in Japan in which participants in the scanner saw that strangers had characterized them as sincere or dependable. Having someone we have never met and have no expectation of meeting provide us with tepid praise doesn’t seem like it would be all that rewarding. And yet it reliably activated the reward systems in the subjects’ brains. In other words, Sally Field really was speaking for us all when she expressed her delight at being liked by others—even people she’ll never meet.

Reprinted from SOCIAL: Why Our Brains Are Wired to Connect. Copyright © 2014 by Matthew D. Lieberman. Published by Broadway Books, an imprint of Random House LLC.