Why do we say one thing but do something else? We announce we're on a diet and gobble down a burger. Brian Knutson does brain scans as people make decisions, and he's beginning to sort out where and when decisions are made and what can affect them. He's observed brain activity that correlates with anticipatory emotions or what people feel just before they choose. And he believes that some psychiatric disorders, such as phobias and schizophrenia, could result from imbalances in decision-making circuits.