Every year, millions of people are unfaithful in their romantic relationships — risking the integrity of their families, finances, and reputations. In surveys, approximately half of unfaithful individuals report that they were happy with their primary relationships when their affairs began. Why would so many people engage in behavior that’s so obviously self-defeating?

Couple therapists and self-help books tell us that infidelity results from familiar factors – like stress, poor communication, childhood issues, and substance use. Such factors do play a role, but they are, at most, half the story. What these explanations leave out is the human brain – along with the last few decades of psychological science, which have done nothing less than revolutionize scientists’ understanding of the origins, or sources, of a person’s behavior.

For most of the 20th century, the notion that unconscious processes play a significant role in human decisions and behaviors was taboo in the scientific community. However, due to many critical discoveries, this changed radically during the 1980s and 1990s. By the start of our present century, scientists had concluded that unconscious processes drive most of our thoughts and actions.

Unfaithful Minds chronicles the discovery of key hidden brain processes, explains their functions, and reveals the specific ways that they influence — and sometimes hijack— unfaithful individuals’ decisions. Because this is the first book to address the role of hidden brain processes in infidelity, it provides a fundamentally new understanding of unfaithful behavior— and even explains why so many happily married people cheat.