In which schedule is reinforcement delivered after a varying number of responses, making rewards unpredictable and often highly resistant to extinction?

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

Answer: (B)

This question is about how different reinforcement schedules shape how eagerly and how long a dog keeps performing a behavior. In a variable ratio schedule, reinforcement is given after a changing, unpredictable number of responses. Because the next reward could come at any attempt, the dog keeps responding at a high, steady rate and is very resistant to extinction—the behavior tends to persist even if rewards become infrequent or stop briefly.

Think of it this way: the unpredictability of the reward keeps the dog guessing, so it doesn’t slow down. That contrasts with a fixed ratio schedule, where rewards come after a set number of responses, producing a quick burst of effort followed by a pause. A fixed interval rewards after a fixed time regardless of responses and leads to a pattern of accelerating responses as the time for the next reward approaches, then a pause. A variable interval rewards after unpredictable time lapses, yielding steady but moderate responding since timing is uncertain but not tied to the number of responses. The scenario described fits the variable ratio pattern best.