Choice between response units: The rate constancy model.
Pigeons split their time between tasks in the same ratio as the reinforcers, even when that choice gives fewer total rewards.
01Research in Context
What this study did
Pierce et al. (1983) let pigeons peck on two keys. One key gave grain on a random-interval schedule. The other key gave grain on a DRL schedule.
The birds could switch any time. The team watched how the birds split their time between the two keys.
What they found
The birds matched their time to the relative rate of grain, not to the absolute rate.
They did not pick the key that gave the most grain overall. They simply kept the same time ratio as the grain ratio.
How this fits with other research
Aragona et al. (1975) saw pigeons maximize grain on concurrent ratio schedules. D et al. used RI-DRL schedules and saw no maximizing. The schedule type decides which rule wins.
Davison et al. (1989) later showed that even on concurrent VI schedules, adding extra grain to both sides does not push birds toward the richer side. Both papers punch holes in simple maximizing ideas.
Malone (1976) already showed that response rates can stay stable on each key. D et al. built on that idea and turned it into a full time-allocation model.
Why it matters
When you set up two tasks for a client, watch time, not just response count. If the reinforcer rates differ, the client will likely match time to the ratio you provide, not chase the richer side. You can predict this without extra probes.
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Join Free →Track minutes on each task, divide by total minutes, then compare that fraction to the fraction of reinforcers delivered on each task; if they match, your setup is following the relative-rate rule.
02At a glance
03Original abstract
In a conjoint schedule, reinforcement is available simultaneously on two or more schedules for the same response. The present experiments provided food for key pecking on both a random-interval and a differential-reinforcement-of-low-rate (DRL) schedule. Experiment 1 involved ordinary DRL schedules; Experiment 2 added an external stimulus to indicate when the required interresponse time had elapsed. In both experiments, the potential reinforcer frequency from each component was varied by means of a second-order fixed-ratio schedule, and the DRL time parameter was changed as well. Response rates were described by a model stating that time allocation to each component matches the relative frequency of reinforcement for that component. When spending time in a given component, the subject is assumed to respond at the rate characteristic of baseline performance. This model appeared preferable to the absolute-rate version of the matching law. The model was shown to be applicable to multiple-response concurrent schedules as well as to conjoint schedules, and it described some of the necessary conditions for response matching, undermatching, and bias. In addition, the pigeons did not optimize reinforcer frequency.
Journal of the experimental analysis of behavior, 1983 · doi:10.1901/jeab.1983.39-275