The roles of stimulus control and reinforcement frequency in modulating the behavioral effects of d-amphetamine in the rat.
A bright light cue protected rat lever-pressing from d-amphetamine disruption even when food rate stayed the same.
01Research in Context
What this study did
Billings et al. (1985) gave rats d-amphetamine while they worked on a spaced-responding task. The rats had to wait a set time between lever presses to earn food.
The team added a bright light cue during some sessions. Reinforcement stayed the same with or without the light. They wanted to know if the cue could protect performance from the drug.
What they found
When the light cue was on, the rats finished their response runs even under the drug. Without the cue, the same dose broke the run pattern.
The benefit held even when the number of food pellets per session stayed identical. Stimulus control, not extra food, saved the day.
How this fits with other research
Lucki et al. (1983) showed that amphetamine hurts or helps depending on the baseline response rate, not on how often food is delivered. Billings et al. (1985) move the spotlight from rate to stimulus control: a simple cue can override rate effects.
LeBlanc et al. (2003) later found that richer food schedules make both response rate and discrimination sturdier against disruption. Billings et al. (1985) already hinted at this by showing that a cue can give the same protection without touching the food schedule.
Gulley et al. (1997) extended the idea to humans with ID. They showed that raising reinforcer frequency can bias which picture gains control in a matching game. Billings et al. (1985) complement this: once a cue has control, its power does not depend on reinforcer frequency.
Why it matters
You can shield operant behavior from disruption by locking it under strong stimulus control. Before increasing reinforcement rate, try adding or sharpening a discriminative stimulus. A distinct cue color, timer beep, or card flip might keep a client on track even when motivation dips or medication changes.
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02At a glance
03Original abstract
The behavioral effects of d-amphetamine have been shown to be modulated by stimulus control, with less impairment of performance occurring when control is great. When the fixed-consecutive-number schedule is used (on which at least a specified consecutive number of responses must be made on one operandum before a single response on another will produce a reinforcer), response rate tends to be invariant but reinforcement frequency is not. This study asks whether the differences in reinforcement frequency that usually accompany changes in stimulus control could themselves be responsible for the performance differences. Two versions of the fixed-consecutive-number schedule of reinforcement were combined into a multiple schedule within which stimulus control was varied but differences in reinforcement frequency were minimized by omitting some reinforcer deliveries during the component that usually had the higher reinforcement frequency. In one component, a compound discriminative stimulus was added with the eighth consecutive response on the first lever; a single response on the second lever was then reinforced. In the other component, no such stimulus was presented. With no added stimulus, large decreases occurred in the number of runs satisfying the minimum requirement for reinforcement at doses of drug that produced only minimal changes when an added stimulus controlled behavior. Thus, increased stimulus control diminishes the behavioral changes produced by d-amphetamine even when the possible contribution by baseline reinforcement rate is minimized.
Journal of the experimental analysis of behavior, 1985 · doi:10.1901/jeab.1985.43-243