Which schedule of reinforcement uses the number of responses as the criterion for reinforcement?

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

Answer: (B)

Reinforcement schedules can be categorized by whether reinforcement depends on the number of responses or on the passage of time. The criterion here is the number of responses, which makes this a ratio schedule. In ratio schedules, reinforcement is delivered after a specific number of responses, regardless of how much time passes. For example, a fixed ratio might reinforce after every fifth response, while a variable ratio reinforces after an unpredictable number of responses on average. The other options involve time-based criteria: an interval schedule provides reinforcement after a certain amount of time has elapsed, with the first response after that interval eligible for reinforcement; a fixed interval is a specific type of interval with a set time; continuous reinforcement means every response is reinforced. So using the number of responses as the criterion identifies the ratio schedule.