Reward prediction error: dopamine fires on anticipation and surprise, not delivery

Wolfram Schultz's monkey experiments showed dopamine does not fire on the reward itself but on the anticipation and on the error between prediction and reality: once a light reliably preceded juice, the dopamine moved to the light. For marketers this means the gap between anticipation (built by advertising) and delivered reality (the product) is where the emotional payoff - or the letdown - happens.