A quantitative analysis of the behavior maintained by delayed reinforcers.
Delayed reinforcers weaken earlier responses in proportion to the wait, so deliver rewards fast or signal the delay.
01Research in Context
What this study did
Pigeons pecked two keys in order. The first peck started a timer. The food came only after a delay.
The team made the delay longer or shorter. They counted first-key pecks to see if the bird slowed down.
What they found
First-key pecks dropped as the delay grew. Time, not extra pecks, caused the drop.
Long waits weakened the very first response, even though it was far from the food.
How this fits with other research
Davis et al. (1972) saw the same drop with signaled delays. Their birds paused longer after food. Charles et al. add the twist: the weakening travels back in time.
van Timmeren et al. (2016) moved the idea to kids with autism. Brief DTI delays slowed learning. The lab result now guides classroom timing.
Richards (1981) showed signals blunt delay damage. Charles used no signals, so the time effect stands bare. The papers fit like puzzle pieces.
Why it matters
Your client’s correct response can be accidentally weakened if you fumble the reinforcer. Keep the gap under two seconds. If you must delay, give a signal so the learner knows the reward is still coming.
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02At a glance
03Original abstract
Random-interval reinforcement was arranged for a sequence of pigeon first-key pecks followed by second-key pecks. First-key pecks, separated from reinforcers by delays that included number of second-key pecks and time, decreased in rate as delays increased. Delay functions, or gradients, were obtained in one experiment with reinforced sequences consisting of M first-key pecks followed by N second-key pecks (M + N = 16), in a second where required first-key pecks were held constant (M = 8), and in a third where minimum delay between most recent first-key pecks and reinforcers varied. In each, gradients were equally well fitted by exponential, hyperbolic and logarithmic functions. Performances were insensitive to reinforcer duration and functions were consistent across varied random-interval values. In one more experiment, time and number delays were independently varied using differential reinforcement of rate of second-key pecks. Delay gradients depended primarily on time rather than on number of second-key pecks. Thus, reinforcers have effects based on earlier responses, not just the ones that produced them, with the contribution of each response weighted by the time separating it from the reinforcer rather than by intervening behavior. Situations where unwanted responses (e.g., errors) often precede reinforced corrects can maintain them unless designed to avoid such effects of delay.
Journal of the experimental analysis of behavior, 2015 · doi:10.1002/jeab.138