Researchers trying to attack pain are stymied by a fundamental lack of understanding of pain mechanisms. Pain management is trial-and-error. Sean Mackey, who runs what he calls the "house of pain" at Stanford, is trying to understand pain by seeing how it can be derailed. In one recent study, he found that Stanford students who were madly in love were less susceptible to pain while looking at a picture of their beloved. Distraction is also about as effective as love at reducing pain. But Mackey is especially interested in the love-pain connection: Does the analgesic effect predict which couples will stay together?