Which term describes a reinforcer follows a fixed number of responses?

• A. Fixed Ratio (FR) Reinforcement
• B. Variable Ratio (VR) Reinforcement
• C. Fixed Interval (FI) Reinforcement
• D. Variable Interval (VI) Reinforcement

Answer: (A)

The main idea here is reinforcement schedules that depend on how many times a behavior occurs. When reinforcement is delivered after a fixed number of responses, that’s a fixed ratio arrangement. The reinforcer comes exactly after you complete that set count, and then the count starts over. This tends to produce a high rate of responding because the next reward is always just a fixed number of responses away, though you’ll often see a brief pause right after each reinforcement before you start the next burst.

If you see reinforcement tied to an unpredictable number of responses, that’s a variable ratio schedule, which usually yields very steady, high responding with few or no pauses. If reinforcement depends on time rather than the number of responses, that’s a fixed interval schedule (reward after a fixed amount of time, regardless of how much you’ve responded), which typically creates a post-reinforcement pause followed by a response acceleration as the time window closes. If the time to reinforcement varies, that’s a variable interval schedule, which leads to a steadier, moderate rate of responding without clear pauses.