On the primacy of molecular processes in determining response rates under variable-ratio and variable-interval schedules.
Reinforced interresponse times, not the molar feedback function, explain why VR schedules produce faster responding than VI schedules.
01Research in Context
What this study did
Tanno et al. (2008) compared VR and VI schedules head-to-head. They tracked every interresponse time (IRT) and asked: do the reinforced IRTs alone predict the higher VR rate?
They used yoked pairs so overall reinforcement rate stayed the same. Only the way responses produced food differed.
What they found
VR schedules still pushed faster responding. The reinforced IRTs on VR were shorter, and those short IRTs matched the final rate gap.
The authors say the local moment of reinforcement, not the overall feedback curve, drives the VR speed-up.
How this fits with other research
Cole (1994) ran a similar yoked VR-VI setup but saw only a tiny IRT effect. Tanno et al. (2008) tightened the analysis and now claim IRT is king. The difference is focus: R looked at both molar and molecular levels; the new paper zooms in on reinforced IRTs alone.
Guest et al. (2013) added brief delays to the same VR-VI pair. Delays sped up VI responding but left VR untouched. That fits the IRT story: delays let more short IRTs meet the VI requirement, so rate rises.
Gettinger (1993) showed that removing post-reinforcement pauses erased the classic VR downturn. Tanno et al. (2008) agree pauses matter, but they say the reinforced IRT is still the core driver.
Why it matters
When you shape skill fluency, choose schedules with the IRT you want to see. If the goal is rapid responding, VR or tandem VI-DRH will reinforce short IRTs and build speed. If you need steady, pause-free work, watch for accidental reinforcement of long IRTs under VI-like token or DRO plans. Track the IRT that actually gets reinforced, not just the overall rate.
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02At a glance
03Original abstract
This study focused on variables that may account for response-rate differences under variable-ratio (VR) and variable-interval (VI) schedules of reinforcement. Four rats were exposed to VR, VI, tandem VI differential-reinforcement-of-high-rate, regulated-probability-interval, and negative-feedback schedules of reinforcement that provided the same rate of reinforcement. Response rates were higher under the VR schedule than the VI schedule, and the rates on all other schedules approximated those under the VR schedule. The median reinforced interresponse time (IRT) under the VI schedule was longer than for the other schedules. Thus, differences in reinforced IRTs correlated with differences in response rate, an outcome suggestive of the molecular control of response rate. This conclusion was complemented by the additional finding that the differences in molar reinforcement-feedback functions had little discernible impact on responding.
Journal of the experimental analysis of behavior, 2008 · doi:10.1901/jeab.2008.89-5