Matching, contrast, and equalizing in the concurrent lever-press responding of rats.
Rat lever pressing follows the matching law under twin VI schedules, but later work shows the same pattern can be sub-optimal when VI meets VR.
01Research in Context
What this study did
Spealman et al. (1978) put rats in a box with two levers. Each lever paid off on its own variable-interval schedule. The team changed the payoff rates across conditions.
They recorded every press and the time spent at each lever. The goal was to see if the matching law held for simple lever pressing.
What they found
The rats' response ratios and time ratios almost perfectly tracked the programmed reinforcement ratios. When the left lever delivered 80 percent of the food, the rats made about 80 percent of their presses on it.
A contrast effect showed up: the rate on the unchanging lever drifted up or down depending on what was happening on the other lever.
How this fits with other research
Santi (1978) ran the same setup but used timeout from shock instead of food. The rats still matched time to reinforcement, proving the law works for negative reinforcement too.
Herrnstein et al. (1979) and Davison et al. (1984) throw cold water on the idea. Using concurrent VI-VR schedules, they show matching earns pigeons about 60 fewer reinforcers per hour than a maximizing strategy. They argue the tidy ratios in D et al. may be an artifact of the VI-VI feedback loop, not a deep psychological law.
Green et al. (1999) extend the story with finer data. Visit-level analysis in rats shows brief check-ins on the lean schedule can still serve global optimization, updating the simple matching picture.
Why it matters
The matching law is still your first-line tool for predicting how clients will spread their behavior across available schedules. Just remember it is a description, not a mandate. If you mix VR and VI schedules in treatment, expect clients to leave potential reinforcers on the table. Build in brief changeover delays and track visit length, not just overall responses, to see whether true matching or brief optimization is happening.
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Join Free →Plot the client's response ratio against the reinforcer ratio for two concurrently available tasks; if the points hug the diagonal, matching is at work.
02At a glance
03Original abstract
Five rats pressed levers for food reinforces delivered by several concurrent variable-interval variable-interval schedules. The rate of reinforcement available for responding on one component schedule was held constant at 60 reinforcers per hour. The rate of reinforcement available for responding on the other schedule varied from 30 to 240 reinforcers per hour. The behavior of the rats resembled the behavior of pigeons pecking keys for food reinforcers. The ratio of the overall rates of responding emitted under, and the ratio of the time spent responding under, the two components of each concurrent schedule were approximately equal to the ratio of the overall rates of reinforcement obtained from the components. The overall rate of responding emitted under, and the time spent responding under, the variable component schedule varied directly with the overall rate of reinforcement from that schedule. The overall rate of responding emitted under, and the time spent responding under, the constant component schedule varied inversely with the overall rate of reinforcement obtained from the variable component. The local rates of responding emitted under, and the local rates of reinforcement obtained from, the two components did not differ consistently across subjects. But they were not exactly equal either.
Journal of the experimental analysis of behavior, 1978 · doi:10.1901/jeab.1978.29-453