The Dopamine Loop: Chemistry of Yearning

Dopamine is often called the pleasure chemical, but research by Kent Berridge and others suggests it has more to do with wanting than liking: it drives us to seek a reward rather than simply making us enjoy it.

Wolfram Schultz found that dopamine neurons respond most strongly to rewards that are better than expected. Feeds, like slot machines, deliver good things unpredictably, which keeps us checking.