Operant Extinction after Fixed-interval Reinforcement with Young Children.

Four preschoolers first earned candy on fixed-interval schedules: 20 s, 30 s, or 60 s.

After each child showed steady FI responding, reinforcement stopped. The team simply watched what the kids did next.

When candy ended, each child kept pressing but in a special FI pattern: long pause, then quick burst near the old payoff time.

These "extinction scallops" matched the timing they had learned, showing the schedule left a clear footprint even without reward.

Jaffe et al. (2002) later asked if we can speed up extinction in autistic preschoolers. They slipped a minute of continuous candy right before the stop. Kids quit faster, building on the 1958 baseline pattern.

Fisher et al. (2019) worked with older children who had problem behavior. They saw resurgence when extinction began after rich FCT reinforcement. Higher past rates meant bigger relapse, echoing how the 1958 FI history kept control.

Craig et al. (2018) showed that reinforcement history in other settings can lower extinction resistance. Their off-baseline trick adds a layer to the simple stop-used-here, giving you one more dial to turn.

You now know that FI schedules stamp a timing signature that survives even when reinforcement ends. If you run DRA or FCT on a lean FI, expect pauses and bursts when you move to extinction. Try slipping a brief stretch of rich reinforcement just before the stop, or thin alternate behaviors off-baseline, to soften that resistance.