Reinforcement magnitude and the inhibiting effect of reinforcement.
On concurrent schedules, boosting reinforcement on one alternative suppresses responding on the other by shrinking the relative value of its reinforcement-correlated stimulus change.
01Research in Context
What this study did
Wetherington (1979) worked with pigeons on two side-by-side keys. Each key paid off on its own variable-interval schedule.
The team kept one key the same. They raised the amount of food per payoff on the other key. Then they watched what happened to the first key.
What they found
When the rich key got richer, the steady key lost value. Peck rate on that key dropped.
The stimulus tied to the steady key now signaled less, so the birds worked there less.
How this fits with other research
Azrin et al. (1969) saw the same drop ten years earlier. They used longer, not bigger, payoffs. Both studies show that juicing one side of a concurrent pair hurts the other side.
SHETTLEWORTCHARNEY et al. (1965) looks like the opposite. Bigger reinforcers raised response rate in their multiple schedule. The key difference is schedule type. In multiple schedules only one component runs at a time. In concurrent schedules both run together, so relative value matters.
Harrison et al. (1975) muddies the water. They added signals to reinforcers and saw response rate rise on the other key. Signalling can override the simple value drop L found.
Why it matters
When you run two teaching programs at once, pumping extra reward into one can quietly drain motivation from the other. Watch for this if you mix high-preference edibles with lower-preference tasks. Balance the value or the lean side may stall.
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02At a glance
03Original abstract
In a two-key concurrent variable-interval schedule (using pigeons), if the reinforcement frequency for one response is held constant while that for the other is increased, the rate of response on the constant key decreases. The immediate reinforcement for key pecking can usually be conceptualized as the change from a condition in which the key light is on and the food hopper light is off to one in which the key light is off and the hopper light is on. The prechange condition is associated with a delay to food of one-half the average interreinforcement interval in effect during this condition. The postchange condition is associated with a delay to food of about .5 seconds. The programming of additional reinforcement results in a decrease in the delay to food associated with the prechange stimulus condition, and thus a decrease in the value of the improvement that results from the change. This would appear to be analogous to a decrease in the amount of reinforcement, and thus sufficient explanation for the decrease in the rate of the response.
Journal of the experimental analysis of behavior, 1979 · doi:10.1901/jeab.1979.32-265