What is reward prediction error

Reward prediction error (RPE) is the difference between the reward you expected and the reward you actually received. 1

• Dopamine signals RPE: An unexpected positive reward can produce a larger dopamine response; if an expected reward fails to arrive or falls short, dopamine can drop below baseline. 1 2
• RPE supports learning and habits: Dopamine-related RPE helps shape learning; behaviors associated with a reward are more likely to happen again, while a missing expected reward can discourage the behavior. 3 4
• Expectations matter for motivation: Clear expectations help avoid disappointment. For example, a vague promise such as “maybe” can be heard as a definite reward, making its later absence more disappointing. 5