Mind & EverydayFact
Why pigeons, slot machines and your feed use the same trick.
B. F. Skinner found that if you reward a pigeon not for every peck but unpredictably, it pecks far more often and barely stops. This variable reinforcement produces the most persistent behaviour known. Slot machines use it, and so does a feed where sometimes a great post appears and sometimes a boring one.
Useful: Unpredictable reward is the core of every addictive design. Once you spot it, it loses power.
Source: en.wikipedia.org