How are rewards delivered under variable schedules?

• A. After an unpredictable number of responses (ratio) or after unpredictable durations (interval).
• B. After a fixed number of responses.
• C. After every response.
• D. After a predictable duration.

Answer: (A)

Rewards under variable schedules are delivered after an unpredictable number of responses or after an unpredictable amount of time. In a variable ratio schedule, reinforcement comes after a random number of responses, so the dog keeps working because rewards are not predictably timed. In a variable interval schedule, reinforcement occurs after varying time intervals, so the dog maintains steady responding since a reward could come at any moment. This unpredictability helps the behavior persist and maintains higher response rates than fixed or continuous schedules. By contrast, fixed patterns—reward after a set number of responses, after every response, or after a predictable duration—do not capture the element of unpredictability that defines variable schedules.