Knutson put human participants in a brain scanner and conditioned them to expect the opportunity to win money when they saw a special symbol appear on a screen. To win the money, they’d have to press a button to get the reward. As soon as the symbol appeared, the brain’s dopamine-releasing reward center lit up, and the participants pressed the button to get their reward. When the participants actually won money, however, this area of the brain quieted down. The joy of winning was registered in different areas of the brain. Knutson had proven that dopamine is for action, not happiness.
