Theory of Mind

Theory of Mind is about as close to mind-reading as people can get. Most formal definitions go along the lines of the ability to discern the intentions, and motivations of yourself or another person. To develop a Theory of their Mind, hence the term. I think it has two components to it, especially if you're talking about one person trying to understand another's behavioral space. 

First, it's the ability to penetrate inside someone else's psychological interiors and understand the rewards and punishment systems inside that interior.Second, it's the ability to understand at all times that the rewards and punishment systems inside your head are not necessarily the same ones inside your neighbor's head. But he or she is not going to react like you do because he or she doesn't have the same rewards and punishment systems you do.

I joke in the book about calling the following saying John Medina's Second Law of marriage. Here's the saying: what is obvious to you is obvious to you.

I believe Theory of Mind skills are very important in the establishment and maintenance of social relationships. Necessary for success, though I would argue not sufficient. People often confuse it with empathy, but there are important distinctions. You can have terrific Theory of Mind skills and be a Mother Teresa. You read people insightfully and care about what you see. You can also be an SOB with it, too. You can read people insightfully and manipulate them in order to achieve some goal of yours. A dictator may be born with terrific Theory of Mind skills, but they use their talents to squash anybody that gets in their way.