Even the faintest whiff of lemon sells cleaning products. Negative messages from politicians win votes. Product placement in films rarely works. Buyology reveals for the first time what actually goes on inside our heads when we see an advertisement, hear a marketing slogan or watch a programme sponsored by a major company. The conclusions are both startling and groundbreaking, showing the extent to which we deceive ourselves when we think we are making considered decisions, and revealing factors as varied as childhood memories and religious belief that come together to influence our decisions and shape our tastes.