Describe the four schedules of reinforcement and give one example for each

What will be an ideal response?

ANS: Students' answers will vary.
Skinner pointed out that in everyday life outside the psychology laboratory, our behavior is rarely reinforced every time it occurs. In a Skinner box, after observing that the rats continued to press the bar at a fairly constant rate even when they were not being reinforced for each response, Skinner decided to investigate different reinforcement schedules to determine their effectiveness in controlling behavior. Among the rates of reinforcement he tested are the following.

• Fixed interval


• Fixed ratio


• Variable interval


• Variable ratio

Fixed interval: A fixed-interval schedule of reinforcement means that the reinforcer is presented following the first response that occurs after a fixed time interval has elapsed. That interval might be 1 minute, 3 minutes, or any other fixed period of time. The timing of the reinforcement has nothing to do with the number of responses. A job in which your salary is paid once a week or once a month operates on the fixed-interval schedule.

Fixed ratio: In the fixed-ratio schedule of reinforcement, reinforcers are given only after a specified number of responses have been made. For example, the experimenter could reinforce after every 10th or 20th response. In this schedule, unlike the fixed-interval schedule, the presentation of reinforcers depends on how often the subject responds. The higher response rate for the fixed-ratio reinforcement schedule also applies to humans. In a job in which your pay is determined on a piece-rate basis, how much you earn depends on how much you produce.

Variable interval: In the variable-interval schedule of reinforcement, the reinforcer might appear after 2 hours the first time, after 1 hour 30 minutes the next time, and after 2 hours and 15 minutes the third time. A person who spends the day fishing might be rewarded, if at all, on a variable-interval basis.

Variable ratio: A variable-ratio schedule of reinforcement is based on an average number of responses between reinforcers, but there is great variability around that average. Skinner found that the variable-ratio schedule is effective in bringing about high and stable response rates, as the people who operate gambling casinos can happily attest. Slot machines, roulette wheels, horse races, and state lottery games pay on a variable-ratio reinforcement schedule, an extremely effective means of controlling behavior.