Concurrent performances: rate constancies without changeover delays.
Concurrent schedules can keep each alternative running at its own steady pace, no change-over delay needed.
01Research in Context
What this study did
The team put two keys in a pigeon box. Each key paid food on its own VI schedule. There was no change-over delay. Birds could hop back and forth any time.
The plan was simple: watch if the rate on one key stays steady even when the other key’s schedule changes.
What they found
Each key kept its own stable rate. When the left key moved to extinction, only left-key pecks dropped. Right-key pecks did not budge.
The birds acted like the two keys were separate jobs, not one big choice.
How this fits with other research
Macdonald et al. (1973) saw pigeons match overall time to payoff, a classic matching-law result. Malone (1976) shows the same birds can also keep two steady, independent rates. The papers sit side-by-side: one highlights choice proportions, the other highlights separate response units.
McGonigle et al. (1982) later proved the units still talk to each other. When they forced rich-key pecks down, lean-key pecks rose. That extends Malone (1976): independence is real, but not absolute.
Catania et al. (1974) swapped food for cocaine in monkeys and still got orderly allocation. The schedule layout stayed the same; the reinforcer changed. This conceptual replication tells us the pigeon findings aren’t tied to grain.
Why it matters
If you run two teaching programs at once, think of each as its own key. Rates can stay steady without extra ‘switch’ penalties. You can probe one skill (extinction, new criteria) while the other hums along. Watch for crossover, though—later work shows big drops in one stream can inflate the other.
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02At a glance
03Original abstract
Pigeons' pecks on two keys were maintained, without changeover delays, by independent variable-interval schedules of food reinforcement. Four regularly cycling 2-min components scheduled reinforcement respectively for both keys, left key only, both keys, and right key only. Initially, reinforcement scheduled for one key alone produced more responding on that key than reinforcement scheduled concurrently for both keys. Continued sessions reduced this difference; response rate on a given key approached constancy, or invariance with respect to the performance on and schedule for the other key. When extinction replaced the reinforcement schedule on either key, responding on that key decreased more during components that scheduled reinforcement for the other key than during those that did not. This demonstration that responses on one key were not supported by reinforcers on the other key suggested that the alternation of concurrent responding and either-key-alone responding prevented concurrent superstitions from developing.
Journal of the experimental analysis of behavior, 1976 · doi:10.1901/jeab.1976.25-377