| List I Types of Reinforcement schedule | List II Definition | ||
| A. | Fixed-ratio | I. | Reinforcement occurs after a set time period |
| B. | Variable-interval | II. | Reinforcement occurs after a set number of responses |
| C. | Fixed-interval | III. | Reinforcement occurs after a varying time period |
| D. | Variable-ratio | IV. | Reinforcement occurs after a varying number of responses |


