Nicholas Epley’s stomach churned as he waited to meet the biological father of his adopted son and daughter from Ethiopia. He couldn’t imagine the man’s emotions as he prepared to release his children to Epley and his wife. When they met, the man cried—but out of sadness, joy, or what, Epley could not know. There were smiles and hugs, but with disparate languages and life experiences, the meaning of those gestures and expressions remained out of reach. “Our minds were so far apart and there was nothing I could do to bridge that,” Epley says. “It’s so easy to misinterpret what the tears meant, what the hug meant. I didn’t know.”

A Chicago Booth behavioral psychologist, Epley studies the human capacity to understand other people’s minds. We’re pretty good at it, displaying “social intelligence” that distinguishes our species. The problem is, we think we’re better at it than we really are.

Epley discusses his new book on the subject, Mindwise: How We Understand What Others Think, Believe, Feel, and Want (Alfred A. Knopf), in an interview with the Magazine, edited and adapted below.

Thought experiments Married couples are slightly better than chance at predicting each other’s thoughts in our experiments, but they think they’re markedly better than chance. Same thing with lie detection. We’re better than chance but not nearly as good as we think we are.

Of two minds Other people have thoughts, feelings, beliefs, or attitudes, but if we remain disengaged from them, we tend to think of others as relatively mindless. So bosses in firms, for instance, tend to think that their employees care less about intrinsic sources of motivation—like pride, or self-respect, or doing something worthwhile—than they do themselves. They haven’t thought about what their employees want in a way that humanizes them fully.

Group think Stereotypes, contrary to popular opinion, are actually a very good source of accuracy. They’re one of the things that get our accuracy levels above chance. But the problem with defining groups by their differences is that you tend to overlook their similarities. When you ask Republicans, they tend to think Democrats have more extreme views than they actually do, and vice versa. We get the direction of differences right, but the magnitude may be way off.

The limits of body language I rode on the train this morning. There was a huge range of emotions on that train. Everybody looked the same. Body language conveys emotion only to the extent that you’re willing to express it, and we just don’t express nearly as much as we think we do.

Quieter than words We tend to assume simple correspondence between people’s actions and their thoughts. I think the most compelling example, at least from recent years, is people’s understanding of Hurricane Katrina. You’ve got a category 5 hurricane bearing down on New Orleans, and some people chose to stay. That’s what it seems like. The language was some people “chose” to stay. But if you look at their situation, it was radically different from those who left. The people who stayed were much poorer, much less likely to have a car. They had much narrower social circles because they were poor, so they didn’t know people who lived out of town that they could stay with. You don’t have a choice there.

A mile in their shoes In [research into] negotiations, we have you put yourself in the shoes of the opposition. We don’t find that people gain insight, that they’re better able to predict what the other side wants, how they’re going to act, what their intentions are. It’s still an open empirical question, but we’ve tried over and over again and we just don’t find evidence that this bit of mental gymnastics, trying to put myself in your shoes, increases accuracy.

Say you, say me If you can’t actually be in somebody’s shoes, you have to get their perspective directly, and you do that through language. A person’s mind comes through their mouth. That’s it. That doesn’t mean it’s simple. When my kids lie, I want to know what the truth is, and they might be afraid to tell me. Getting perspective requires asking questions and putting people in a position where they can tell you the truth.