Which term describes reinforcement delivered after a fixed amount of time since the last reinforcement opportunity, regardless of responses?

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

Answer: (A)

This item tests understanding of a time-based reinforcement schedule where the reinforcement is delivered after a fixed amount of time has passed since the last reinforcement opportunity, independent of how many responses occur. In this schedule, the timer is set to a constant interval, and the first response after that interval yields reinforcement. Because the opportunity to obtain reinforcement is tied to time, not the number of responses, behavior tends to show a pattern where responding increases as the interval’s end approaches, followed by a brief pause right after reinforcement. For example, if reinforcement becomes available every two minutes, the subject will often respond more as the two-minute mark nears, and the next rewarded response occurs after that fixed two-minute interval regardless of how many responses have been made inside it. This distinguishes it from interval schedules that vary the time between opportunities or from ratio schedules that tie reinforcement to a set or varying number of responses rather than to elapsed time.