Some effects of interreinforcement time upon choice.
Chaining schedules can depress choice; momentary reinforcement likelihoods matter more than overall rates.
01Research in Context
What this study did
Researchers watched pigeons choose between two keys. Each key led to a different chain of colored lights before food arrived.
They changed how the chains were built. Sometimes both parts of the chain ran at the same time. Sometimes they ran one after the other.
The team wanted to know if the way the chain was wired changed which key the birds pecked.
What they found
When the last part of the chain ran at the same time as the first part, birds over-matched. They picked the key with the shorter wait more than the math said they should.
Chaining itself made the birds less willing to work. The birds cared about the wait right now, not the average wait across the whole session.
How this fits with other research
Wacker et al. (1985) and Reed et al. (1988) ran almost the same test. They also saw birds avoid chained schedules. The longer the chain or the more pieces it had, the stronger the dislike.
Henton (1972) looks like a contradiction. That lab found no difference between chained and tandem schedules. The key difference is procedure: W kept the initial links running side-by-side all the time, while E et al. switched between three set-ups. Small design tweaks can hide or show the chaining penalty.
Duncan et al. (1972), published the same year, adds another vote against chains. Even when total delay to food stayed the same, adding extra links hurt preference.
Why it matters
If you break a reinforcement schedule into too many steps, clients may lose interest. Keep teaching chains short and deliver the big reinforcer quickly. When you must use several steps, let the learner see the final payoff as early as possible. Watch moment-to-moment wait times, not just the overall rate of reinforcement.
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02At a glance
03Original abstract
Pigeons' responses were reinforced on two identical and concurrently available chain variable-interval-schedules. Unlike the typical concurrent chains procedure, both links were operative throughout, thus producing three types of concurrency: (1) concurrent initial links; (2) concurrent initial and terminal links; (3) concurrent terminal links. Choice proportions in each of these three states suggested that the pigeons were sensitive to momentary likelihoods of reinforcement: choice proportions for a schedule were higher when the schedule had been operative for some time, resulting in a higher probability of reinforcement. The study also showed that the relative rates of responding did not match the relative rates of reinforcement in any of the three states of concurrency. Instead, the choice proportions in both the concurrent initial and in the concurrent terminal links were intermediate between the scheduled and the obtained relative rates of reinforcement, while the choice proportions for a terminal link concurrent with an initial link consistently overmatched the relative interreinforcement times (and were typically 1.00). These data indicate that an accurate characterization of choice may not be obtained by considering only the relative interreinforcement interval where one interreinforcement interval is segmented into a chain. Instead, the organism's choice for a schedule will be substantially lowered by the chaining operation.
Journal of the experimental analysis of behavior, 1972 · doi:10.1901/jeab.1972.17-3