A local model of concurrent performance.
Concurrent choice can be predicted from local stay/switch reinforcement odds alone.
01Research in Context
What this study did
Malone (1999) watched rats work on two levers at once.
Each lever paid off on its own clock.
The team logged how long the rat stayed on one lever before switching.
They asked: do the animals need to compare both rates, or is each stay ruled only by the last few payoffs on that lever?
What they found
Run length and visit time followed a simple power rule.
Only the stay-versus-switch payoff ratio on the current lever mattered.
The rats acted as if the other lever did not exist.
This supports a local, not global, account of concurrent choice.
How this fits with other research
Cohen (1975) claimed time allocation, not local pattern, drives choice. Malone (1999) counters by deriving choice from local stay/switch odds alone.
White (1979) showed pigeons switch memory-free. Malone (1999) gives the same idea a math form and shows it works for rats too.
Avellaneda et al. (2025) later updated the matching law so sensitivity can slide with overall rate. They keep J’s local spirit but add a molar dial for better fit.
Why it matters
You can now treat each alternative as its own mini schedule. Track how often reinforcement follows a stay versus a switch on that task. Plug those two numbers into a power function and you will predict how long the client will stick before moving on. No need to tally the whole session. This speeds assessment in vocational and leisure choice programs where clients move between stations or apps.
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Join Free →Count the last three reinforcers on the current task; note how many followed staying versus switching and use that ratio to guess when the client will move on.
02At a glance
03Original abstract
Concurrent procedures may be conceptualized as consisting of two pairs of schedules with only one pair operating at a time. One schedule of each pair arranges reinforcers for staying in the current alternative, and the other schedule arranges reinforcers for switching to the other alternative. These pairs alternate operation as the animal switches between choices. This analysis of the contingencies suggests that variables operating within an alternative produce behavior that conforms to the generalized matching law. Rats were exposed to one pair of stay and switch schedules in each condition, and the probabilities of reinforcement varied across conditions. Both run length and visit duration were power functions of the ratio of the probabilities of reinforcement for staying and switching. The local model, a model of performance on concurrent procedures, was derived from this power function. Performance on concurrent schedules was synthesized from the performances on the separate pairs. Both the generalized matching law and the local model fitted the synthesized concurrent performances. These results are consistent with the view that the contingencies in the alternative, the probability of stay and switch reinforcement, are responsible for performance consistent with the generalized matching law. These results are compatible with momentary maximizing and molar maximizing accounts of concurrent performance. Models of concurrent performance that posit comparisons among the alternatives are not easily applied to these results.
Journal of the experimental analysis of behavior, 1999 · doi:10.1901/jeab.1999.71-57