Food-paired stimuli as conditioned reinforcers: effects of d-amphetamine.
Amphetamine turns food-linked cues into super-reinforcers, so behavior sticks around longer when the real reward stops.
01Research in Context
What this study did
Fields et al. (1991) gave lab animals a light that had been paired with food.
Then they removed the food and watched how many times the animals pressed a lever for the light alone.
Half the sessions were run after a dose of d-amphetamine; half after saline.
What they found
The drug made the food-paired light a stronger reward.
Animals worked harder for the stimulus during extinction when amphetamine was on board.
A separate cue that signaled "no food coming" boosted this effect even more.
How this fits with other research
Kelleher (1966) first showed that a brief light can keep an animal pressing if it once accompanied food. Fields et al. (1991) add the twist: the same light becomes more powerful under amphetamine.
KELLEHER (1961) warned that conditioned reinforcers can slow extinction. The new data prove the drug widens this slow-down, so behavior persists longer without food.
Au-Yeung et al. (2015) later asked whether tokens or food make behavior tougher to stop. They saw mixed results with humans. Fields et al. (1991) clarify the drug side: amphetamine always tips the scale toward the conditioned reinforcer.
Why it matters
If you run extinction or token boards, remember that internal or external stimulants can magnify the value of your conditioned reinforcers. Check what medications your client takes. Watch for unexpected persistence of behavior when primary rewards are removed. You may need longer extinction phases or tighter stimulus control when amphetamine or similar drugs are in effect.
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02At a glance
03Original abstract
Seven pigeons were studied in two experiments in which key pecks were reinforced under a second-order schedule wherein satisfaction of variable-interval schedule requirements produced food or a brief stimulus. In the second part of each session, responses produced only the brief stimulus according to a variable-interval schedule (food extinction). For the 4 pigeons in Experiment 1, the response key was red throughout the session. In separate phases, the brief stimulus was either paired with food, not paired with food, or not presented during extinction. d-Amphetamine (0.3 to 10.0 mg/kg) dose-dependently reduced food-maintained responding during the first part of the session and, at intermediate dosages, increased responding during the extinction portion of the session. The magnitude of these increases, however, did not consistently depend on whether the brief stimulus was paired, not paired, or not presented. It was also true that under nondrug conditions, response rates during extinction did not differ reliably depending on pairing operations for the brief stimulus. In Experiment 2, 3 different pigeons responded under a procedure wherein the key was red in the component with food presentations and blue in the extinction component (i.e., multiple schedule). Again, d-amphetamine produced dose-related decreases in responding during the first part of a session and increases in responding in the second part of the session. These increases, however, were related to the pairing operations; larger increases were observed when the brief stimulus was paired with food than when it was not or when it was not presented at all. Under nondrug conditions, the paired brief stimulus controlled higher response rates during extinction than did a nonpaired stimulus or no stimulus. These findings suggest that d-amphetamine can enhance the efficacy of conditioned reinforcers, and that this effect may be more robust if conditioned reinforcers occur in the context of a signaled period of extinction.
Journal of the experimental analysis of behavior, 1991 · doi:10.1901/jeab.1991.56-277