The magnitude-of-reinforcement function in closed and open economies.
Response rate is not a straight read of reinforcement strength; open versus closed economy context decides whether bigger rewards push responding up.
01Research in Context
What this study did
Raslear et al. (1992) worked with rats in two kinds of chambers.
In a closed economy the rats earned every food pellet by pressing a lever.
In an open economy the rats could also get free pellets after the session.
The team changed pellet size and how many presses each pellet cost.
They watched how fast the rats pressed under each setup.
What they found
In the closed economy smaller, costly pellets made the rats press faster.
In the open economy pellet size and cost hardly mattered.
Response rate was not a pure measure of how good the food was.
The wider context, open or closed, decided what magnitude meant.
How this fits with other research
STEBBINS et al. (1959) had earlier shown that bigger rewards give faster pressing.
The new study does not erase that fact; it shows the fact only holds in closed economies.
Iwata et al. (1990) ran a near-copy of the open-closed setup with a different schedule and saw the same pattern, giving a direct replication.
Iwata (1993) went further and showed that simply cutting free food also boosts pressing, extending the economic story to response-independent reinforcers.
Why it matters
If your client can gain reinforcers outside the session, reward size inside the session may not drive behavior.
Check the wider environment before you increase token value or treat size.
Try running a short closed-economy probe: withhold outside access and watch if smaller, costlier rewards now speed up responding.
This quick test tells you whether magnitude or context is the real lever.
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02At a glance
03Original abstract
It has been hypothesized that the magnitude-of-reinforcement effect may differ in closed and open experimental economies. We determined the relationship between magnitude of reinforcement and response rate in three feeding conditions: a closed economy in which total intake was unrestricted, a closed economy in which total intake was restricted so as to maintain body weight at 85% of free-feeding weight, and a traditional open economy in which subjects received food outside the experimental session. In the closed economies, regardless of body weight, the rats responded faster for smaller pellets and when the fixed ratio for pellets was higher. In the open economy, there was no reliable effect of pellet size or pellet cost on response rate. It is concluded that although there are circumstances in which response rate is an immediate function of the parameters of reinforcement, rate is not necessarily a measure of response strength. Response rate may instead, or additionally, contribute to a strategy of reducing the costs associated with resource utilization.
Journal of the experimental analysis of behavior, 1992 · doi:10.1901/jeab.1992.57-81