Which schedule describes reinforcement delivered after a variable number of responses?

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

Answer: (C)

This question tests how reinforcement is scheduled based on responses and whether that criterion is fixed or variable. The pattern described—reinforcement delivered after an unpredictable number of responses—maps to a variable-ratio schedule. Because the number of responses needed is not known in advance, the learner keeps responding quickly and consistently, since reinforcement could come at any moment. A familiar example is gambling games where rewards come after a changing number of pulls, which sustains high response rates.

By contrast, fixed-interval reinforcement happens after a set amount of time regardless of how many responses are made, leading to a noticeable post-reinforcement pause and a scalloped pattern; variable-interval reinforcement occurs after varying time periods, producing steady but moderate responding; fixed-ratio reinforcement occurs after a fixed number of responses, often with bursts of activity followed by short pauses.