Today I saw something I’ve never seen before: a man breaking out into dance in the supermarket. One aisle over, I caught another shopper smiling and humming along. I don’t normally notice the music being played in shops, but I also felt more energised than I had moments earlier. Whether it be how long you spend in a shop, the amount you spend, even whether you buy French or German wine, music has power over our behaviour. And shops are using it to their advantage.