Rats' performance on variable-interval schedules with a linear feedback loop between response rate and reinforcement rate.
Rats act blind to slow feedback between how fast they respond and how often reinforcement comes.
01Research in Context
What this study did
The team built a special variable-interval schedule. Faster lever presses made food arrive sooner. They called it VI+ because it added a clear feedback loop.
Rats lived in operant chambers day and night. Every session gave them chances to earn grain. The loop tied overall response rate to overall reinforcement rate.
Three experiments compared VI+ with plain VI and VR. Each rat served as its own control. The question: do rats notice and use the loop?
What they found
Response rates stayed the same no matter what. Rats pressed about as fast on VI+ as on yoked VI. The feedback loop did not guide their speed.
Reinforced inter-response times also failed to shift. No pattern showed the animals had detected the molar contingency. The result was a flat null.
How this fits with other research
Davison et al. (1989) saw the same nothing with pigeons. Birds ignored overall reinforcer-rate feedback on concurrent VI. The two nulls stack into a strong case: animals do not sense molar loops.
McGonigle et al. (1982) looks opposite at first glance. They showed that slowing one lever made the other lever speed up. But their change came from moment-to-moment competition, not from sensing a feedback rule. Method matters.
Katz et al. (2003) ran a contemporary pigeon study. Reinforcer ratios changed every few seconds and the birds tracked them fine. Quick, local shifts control behavior; slow, molar loops do not.
Why it matters
If you build interventions that rely on clients noticing long-term rate links, think again. Children, like rats, react to what just happened, not to hidden feedback curves. Design your schedules for immediate, local consequences. Watch moment-to-moment changes instead of waiting for molar drift.
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02At a glance
03Original abstract
Three experiments investigated whether rats are sensitive to the molar properties of a variable-interval (VI) schedule with a positive relation between response rate and reinforcement rate (i.e., a VI+ schedule). In Experiment 1, rats responded faster on a variable ratio (VR) schedule than on a VI+ schedule with an equivalent feedback function. Reinforced interresponse times (IRTs) were shorter on the VR as compared to the VI+ schedule. In Experiments 2 and 3, there was no systematic difference in response rates maintained by a VI+ schedule and a VI schedule yoked in terms of reinforcement rate. This was found both when the yoking procedure was between-subject (Experiment 2) and within-subject (Experiment 3). Mean reinforced IRTs were similar on both the VI+ and yoked VI schedules, but these values were more variable on the VI+ schedule. These results provided no evidence that rats are sensitive to the feedback function relating response rate to reinforcement rate on a VI+ schedule.
Journal of the experimental analysis of behavior, 2003 · doi:10.1901/jeab.2003.79-157