Which schedule reinforces a behavior after a duration that changes unpredictably?

• A. Fixed Duration
• B. Variable Duration
• C. Fixed Interval
• D. Variable Ratio

Answer: (B)

The concept here is reinforcement based on how long the behavior is performed, with the duration not being predictable.

In a variable duration schedule, the required length of time the dog must perform the target behavior changes from trial to trial in an unpredictable way. Reinforcement is delivered only after the behavior has been sustained for that varying duration. Because the duration isn’t known in advance, the animal learns to maintain the behavior until reinforcement occurs, producing persistent, sustained responding.

If the duration were fixed, the dog would simply learn to hold for that known amount of time. If the schedule were based on a fixed or variable interval, reinforcement would depend on elapsed time and a response, not on maintaining the behavior for a duration. If it were based on a fixed or variable ratio, reinforcement would depend on a certain number of responses, not on duration.