Fixed-interval schedules: the scalloped pattern
A student studies very little after each monthly exam but studies more and more as the next exam date approaches. Which reinforcement schedule produces this pattern?
Answer D: explanation for every choice
A
Variable-interval schedules produce steady, moderate responding because the timing is unpredictable.
B
Fixed-ratio schedules tie reward to a number of responses and produce high rates with brief post-reward pauses.
C
Variable-ratio schedules produce high, steady rates with no pause.
D
Correct. When reinforcement becomes available after a predictable time, responding drops after each reward and accelerates near the end of the interval, the “scallop.”
TakeawayFixed-interval: responding speeds up as the expected time approaches.
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Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID ps98.