Better or worse than expected?
One of dopamine’s best-established jobs is to signal whether something turned out better or worse than you expected. Move the sliders to see how that difference drives learning.
This is a teaching model of the idea, not a measurement. The numbers are your ratings, not amounts of dopamine — no online tool can measure dopamine.
What the model shows
- Better than expected ↑ — dopamine neurons fire more. The brain learns: “that was worth it, do it again.”
- As expected → — little change. Nothing new to learn.
- Worse than expected ↓ — activity dips below its usual level. The brain learns: “less of that.”
Over time, expectations move towards what actually happens. That is why the fifth identical treat is less exciting than the first, and why an unpredictable reward — a message that may or may not be there — keeps pulling you back: it never becomes fully expected.
So what?
Expectation is powerful. In one brain-imaging study, people who only believed they might have had caffeine showed a dopamine change similar to the real thing. What you expect shapes what you learn.
Show me the science
- What does dopamine actually do? — prediction error and effort (grade A)
- Does coffee give you a dopamine hit? — the expectation study (grade B)
- Why can’t I stop scrolling? — uncertain rewards