A young woman walks into a laboratory. Over the past two years, she has transformed almost every aspect of her life. She has quit smoking, run a marathon, and been promoted at work. The patterns inside her brain, neurologists discover, have fundamentally changed. Marketers at Procter & Gamble study videos of people making their beds. They are desperately trying to figure out how to sell a new product called Febreze, on track to be one of the biggest...