Rate differential reinforcement in monkey manipulation.
Reinforcement works best when the rewarded response is already the easier one.
01Research in Context
What this study did
One monkey sat in a cage with two objects. Each object made a different response happen.
The team set a rule: press object A, then object B earns food. They swapped which response was first.
They counted how often the monkey touched each object when the rule changed.
What they found
The monkey worked hardest when the second object was the one he already liked to touch.
If the second object was rarely touched on its own, the rule barely worked.
Reinforcement power came from the difference in starting habits, not from the objects themselves.
How this fits with other research
Reynolds et al. (1968) turned this idea into a math formula for pigeons. Response-rate ratios matched reinforcement-rate ratios once the 1963 monkey clue was formalized.
McDowell et al. (2021) added reinforcer size to the same math. Their 2021 equation keeps the 1963 heart: behavior change is always relative.
Cividini-Motta et al. (2024) swept sixty years of DR studies into one guide. They tell you to give the better reinforcer only for the new skill, echoing the 1963 warning to watch baseline odds.
Why it matters
Before you pick a reinforcer, clock the baseline. If the child already talks non-stop, do not make talking the second step. Choose a quiet response that competes less. You will get faster gains and thinner schedules.
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02At a glance
03Original abstract
A set of four manipulanda were presented to four Cebus monkeys, individually, and later in pairs. Step 1 provided an estimate of each S's probability of operating each item, while Step 2 determined whether pairing the items would disturb the ordinal relations among individual response probabilities. Both procedures provided information necessary for testing the assumption that a reinforcer is simply a contingent response whose independent probability of occurrence is greater than that of the associated instrumental response. Step 3 tested this assumption by again presenting pairs of items, but with one locked and its operation made contingent upon operation of the free item of the pair. The four Ss differed markedly in the extent to which the items produced different independent response probabilities, and correspondingly, in the extent to which the contingent pairs subsequently produced reinforcement. Confirmation of the present assumptions came primarily from one S, which differed substantially on the individual items, and showed five cases of reinforcement, all in the predicted direction. Further, reinforcement was shown by an increase in both contingency and extinction sessions. Finally, the response of intermediate probability reinforced the response of least, but not the one of greatest, probability, indicating that a reinforcer cannot be identified absolutely, but only relative to the base response.
Journal of the experimental analysis of behavior, 1963 · doi:10.1901/jeab.1963.6-81