Choice between concurrent schedules.
Pigeons divide responses exactly like they divide pay-offs, giving the cleanest early proof of the matching law.
01Research in Context
What this study did
Macdonald et al. (1973) let six pigeons peck two keys at the same time.
Each key paid off on its own timer. Food came every 30 s on the left key or every 90 s on the right key.
The birds could switch keys any time. The team counted pecks over the study period.
What they found
The birds pecked the left key three times more than the right key.
The ratio of pecks matched the ratio of food almost perfectly.
This tight fit became the classic proof of the matching law.
How this fits with other research
Hall (2005) later showed the simple math fails when the two keys make food available at different speeds. You now need an extra "earning ÷ obtaining" term.
Ghaziuddin et al. (1996) saw cows give mild undermatching, not the strict one-to-one fit seen here. The gap is real but small and tied to species, not theory.
Thompson (1975) swapped birds for adult humans and still got matching, proving the rule travels across species.
Why it matters
Use the matching law as your first guess when clients split time between tasks. If the split drifts, check whether one task lets them earn faster or whether pausing is common. Update your equation with the 2005 earning/obtaining fix when needed.
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02At a glance
03Original abstract
Six pigeons pecked for food in a three-key experiment. A subject at any time could choose the left or right key and receive reinforcement according to one two-key concurrent variable-interval variable-interval schedule of reinforcement, or it could peck the center key. A peck on the center key arranged the complementary two-key concurrent variable-interval variable-interval schedule on the left and right keys. The two different two-key concurrent schedules arranged reinforcements concurrently and were signalled by two different colors of key lights. Choice behavior in the presence of a given color conformed to the usual relationship in two-key concurrent schedules: the relative frequency of responding on a key approximately equalled the relative frequency of reinforcement on that key. Preference for a two-key concurrent schedule, which was equivalent to preference for a color, was measured by the percentage of all responses on the left and right keys in the presence of that color: this percentage approximately equalled the percentage of all reinforcements that were delivered in the presence of that color. Thus, choice between concurrent schedules conforms approximately to the same relationship as does choice between alternatives in a single concurrent schedule.
Journal of the experimental analysis of behavior, 1973 · doi:10.1901/jeab.1973.19-331