Conditioned reinforcement in chain schedules when time to reinforcement is held constant.
A stimulus that reliably predicts reinforcement can boost responding across an entire chain even when the overall wait for the primary reinforcer stays the same.
01Research in Context
What this study did
Peters et al. (2013) worked with pigeons on two-link chained schedules. The birds pecked a key in link one, then moved to link two, then got food.
The team kept total time to food the same. They only changed how often the middle light came on before food. That light acted as a conditioned reinforcer.
What they found
When the middle light was more likely to signal food, pigeons pecked faster in both links. The birds worked harder even though the food stayed the same distance away.
The result shows the value of a conditioned reinforcer can beat out pure delay.
How this fits with other research
Lendenmann et al. (1982) also used two-link chains with pigeons but made the food itself longer, not the signal. Both studies saw faster early-link responding, showing either a richer signal or a longer meal can pump up effort.
Neef et al. (1978) let rats pick between two levers with equal food rates. The rats chose the lever whose light had been paired with water. Peters et al. (2013) echo this: the paired stimulus, not the payoff count, steers the animal.
Lancioni et al. (2011) moved the idea to children. After kids briefly saw which picture meant more tokens, they later picked that task more often. The bird finding that signal value trumps distance now holds for human compliance too.
Why it matters
You can juice up a task chain without adding more candy or break time. Slip in a quick visual or sound that has reliably predicted the big reinforcer, even if it shows up early in the chain. The learner will work harder through every step even though the final prize is no closer. Try it when you thin reinforcement or stretch work periods.
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Join Free →Pick one chain you already run. Add a brief 2-s colored card that has previously been paired with the big reinforcer at the start of the second link; keep total time to reinforcement unchanged and track response rate.
02At a glance
03Original abstract
Two alternative approaches describe determinants of responding to a stimulus temporally distant from primary reinforcement. One emphasizes the temporal relation of each stimulus to the primary reinforcer, with relative proximity of the stimulus determining response rate. A contrasting view emphasizes immediate consequences of responding to the stimulus, the key factor being the conditioned reinforcement value of those immediate consequences. To contrast these approaches, 4 pigeons were exposed to a two-component multiple schedule with three-link chain schedules in each component. Only middle-link stimuli differed between chains. Baseline reinforcement probabilities were 0.50 for both chains; during discrimination phases it was 1.0 for one chain and 0.0 for the other. During discrimination phases pigeons responded more to the reinforcement-correlated middle link than to the extinction-correlated middle link, demonstrating that responding was affected by the probability change. Terminal link responding was also higher in the reinforced chain, even though the terminal link stimulus was identical in both chains. Of greatest interest is initial link responding, which was temporally most distant from reinforcement. Initial link responding, necessarily equal in the two chains, was significantly higher during the 1.0/0.0 discrimination phases, even though overall reinforcement probability remained constant. For 3 of 4 birds, in fact, initial-link response rates were higher than terminal-link response rates, an outcome that can be ascribed only to the potent conditioned reinforcement properties of the middle-link stimulus during the discrimination phases. Results are incompatible with any account of chain behavior based solely on relative time to reinforcement.
Journal of the experimental analysis of behavior, 2013 · doi:10.1002/jeab.10