| Fixed | Variable | |
|---|---|---|
| Ratio | Every so many: reinforcement after every nth behavior, such as buy 10 coffees, get 1 free, or pay workers per product unit produced | After an unpredictable number: reinforcement after a random number of behaviors, as when playing slot machines or fly fishing |
| Interval | Every so often: reinforcement for behavior after a fixed time, such as Tuesday discount prices | Unpredictably often: reinforcement for behavior after a random amount of time, as when checking our phone for a message |