Communicators and marketers aim to change public attitudes every day. But bringing about that change can be frustrating and challenging. As people, we can be stubborn when it comes to our opinions and are reluctant to change our views, let alone how we act and behave. Yet, the situation is not all bleak for those tasked with persuasion, as the big, and rapid, public shifts on social issues such as marriage equality have shown. What do we need to know about how attitudes are formed, and how they might evolve?