The effects of chlordiazepoxide and d-amphetamine during a three-component multiple schedule.
Reinforcement context inside a multiple schedule can turn the same drug dose up or down.
01Research in Context
What this study did
Romanowich et al. (2013) gave two drugs to lab animals working on a three-part schedule.
Each part had its own colored light and its own reinforcement rule.
The team watched how the drugs changed response speed in each part.
What they found
The anti-anxiety drug chlordiazepoxide acted differently in part one and part three.
The difference only showed up when the middle part used a special reinforcement rule.
The stimulant d-amphetamine did not show this pattern; it moved rates up or down the same way no matter what the middle part did.
How this fits with other research
Neuringer (1973) already showed that response-dependent parts create faster responding than response-independent parts.
Paul’s team adds that the same kind of rule change can also steer how a drug alters behavior.
Hineline et al. (1969) found behavioral contrast in chained schedules: when early links paid less, the final link sped up.
Paul’s result is like contrast inside a multiple schedule, but caused by a drug instead of by shifting reinforcement.
Bacon-Prue et al. (1980) used a DRO schedule on top of fixed-interval baselines and saw response patterns flatten.
Paul’s drug acted like a superimposed contingency, again proving that extra context can reshape baseline performance.
Why it matters
If you run multiple schedules or mixed reinforcement programs, remember that medication effects can look stronger or weaker depending on the local contingency.
Before you attribute a change to the drug alone, check what reinforcement rule is active in the prior or middle component.
You might see a dip or boost that is really a schedule-drug interaction, not a medication failure.
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Chart response rate in each component separately after any med change to spot schedule-specific effects.
02At a glance
03Original abstract
Multiple schedules have been used in behavioral pharmacology research to show that a drug's effect on behavior can be a function of the schedule of reinforcement that supports that behavior. However, less research has examined whether the context of the schedule of reinforcement in a multiple schedule can change the drug's effect on behavior. We examined the effects of acute chlordiazepoxide and d-amphetamine injections on the behavior of two groups of pigeons trained on a three-component multiple schedule with identical schedules of reinforcement in the first and last components. For one group of pigeons reinforcement was unavailable during the middle component (decreased-middle-component). For the second group reinforcement rate was higher during the middle component than during the first or third components (increased-middle-component). In the decreased-middle-component group, chlordiazepoxide (3.2-32 mg/kg) decreased third-component response rates less than it decreased responding in the first component. Conversely, in the increased-middle-component group, chlordiazepoxide (3.2-10 mg/kg) decreased third-component response rates more than in the first component. In both groups, d-amphetamine did not differentially affect response rates across components. These results are consistent with previous research showing that drugs can differentially affect responding to two different schedules of reinforcement during the same session, and suggest that pharmacological preparations may be helpful in elucidating the mechanisms that control multiple schedule interactions.
Journal of the experimental analysis of behavior, 2013 · doi:10.1002/jeab.28