When we have conversations about sexual and gender diversity we can quickly become emotional and defensive. We are often baffled how other people can think so differently than we do about these topics. Why is this? In this series of five short episodes, I explore some of the psychological dynamics that can get in the way when we try to stay at the table and have constructive dialogue. In this third episode, I talk about how our minds ensure that we preserve the categories we have learned, and help us defend our beliefs.