Sian Jarvis, the supermarket’s head of corporate affairs, had undermined her claims to care about the health of her customers and let slip one of the secrets of a multi-billion-pound industry ... she revealed that one in three Asda checkouts “are what we call guilt-free checkouts”. Jarvis insisted “guilt-free” was merely “a term that’s commonly used in retail”. But it was too late, and her “guilt” gaffe quickly invited scorn in the industry and among public health professionals. Whatever the damage, she had already opened a door to the arcane science of supermarket psychology. To the designers of the modern store, shoppers are lab rats with trolleys, guided through a maze of aisles by the promise of rewards they never knew they sought The Secrets Of Our Supermarkets