CentralReach (CR) Institute Practice Exam

Fixed-interval schedules create a scalloped pattern because reinforcement is available only after a set amount of time has passed. Right after a reinforcement, responding drops for a short post-reinforcement pause. As the interval progresses, the tendency to obtain reinforcement increases, so the learner responds more rapidly toward the end of the interval. This cycle of a pause followed by a rising rate of responding, then another pause, produces the characteristic scalloped curve. If you compare with other schedules, continuous reinforcement would show a steady, high rate with no pauses; a variable-ratio schedule yields high, consistent responding with few pauses due to reinforcement being delivered after an unpredictable number of responses; a fixed-ratio schedule produces bursts of responding after completing a set number of responses, but the pattern isn’t the same scalloped rise-and-pause sequence.