Which statement describes a variable ratio schedule?

• A. Rewards are delivered after a fixed number of correct responses.
• B. Rewards are given on a random basis so that the reward cannot be predicted.
• C. Rewards are delivered after a fixed time interval.
• D. Rewards are delivered after every response.

Answer: (B)

Rewards after an unpredictable number of responses are the hallmark of a variable ratio schedule. The reinforcement isn’t tied to a fixed count; instead, the number of correct responses required for the next reward varies around a mean, so the next reward cannot be predicted. This keeps the subject responding at a high and steady rate because any response could be the one that earns reinforcement. In dog training, this is useful to maintain motivation and prevent the dog from guessing a pattern. By comparison, a fixed ratio delivers rewards after a set number of responses, a fixed interval after a set amount of time, and continuous reinforcement delivers a reward after every response.