On some determinants of choice in pigeons.
Pigeons split their responses to match payoff rates, but the fit is loose and history tweaks it.
01Research in Context
What this study did
Researchers let pigeons peck two keys at the same time. Each key paid off on its own schedule.
They counted how the birds split their pecks. They also counted how the food was split.
The goal was to see if the peck ratio matched the food ratio.
What they found
The birds' pecks lined up with the payoff rates. If the left key paid 70 % of the food, about 70 % of the pecks hit that key.
This tight link became known as the matching law.
How this fits with other research
Hopkins et al. (1977) later re-checked the numbers. They found the fit is not perfect: pigeons slightly undermatch. They peck the lean side a bit more than strict math says.
Garcia et al. (1973) added a twist. They looked at time on each key, not just pecks. Pecks still matched, but time did not. Response count is the cleaner measure.
Landon et al. (2002) showed history matters. When payoff odds shift, birds adjust both right away and over the long haul.
Why it matters
When you run concurrent schedules with kids, expect the same rough match, not laser precision. Plan for slight undermatching and watch response counts more than time. If you thin one schedule, know the client may keep some responses on that side longer than the math says.
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02At a glance
03Original abstract
A pigeon's pecking at each of two or three simultaneously available red keys was reinforced at different frequencies with a conditioned reinforcer, an orange key, on which 25 pecks resulted in a presentation of grain. Pecking was occasionally punished with a period of no reinforcement during which each key was dark. Both with two and with three keys, the relative frequency of pecking on a key was equal to the relative frequency of reinforcement obtained by pecks on that key. Also, the absolute frequency of pecking on each key was a linear function with zero intercept of the absolute frequency of reinforcement associated with that key. The slope of this function varied with the number of available keys; it was steeper with two than with three. The relative frequency of switching from any key (two successive pecks on different keys) approximated a linear function with zero intercept and slope slightly greater than 1.0 of the total relative frequency of reinforcement associated with the keys to which the bird could switch. However, the relative frequency of switching to a particular key often showed systematic irregularities. The invariance in these data is the equality between the relative frequency of pecks on one of two or three keys and the relative frequency of reinforcement associated with that key.
Journal of the experimental analysis of behavior, 1963 · doi:10.1901/jeab.1963.6-53