Effects of d-amphetamine on responding under second-order schedules of reinforcement with paired and nonpaired brief stimuli.
In pigeons, d-amphetamine flattens response patterns but does not turn brief stimuli into stronger conditioned reinforcers.
01Research in Context
What this study did
Cohen (1991) gave pigeons a second-order schedule. Birds pecked a key to earn brief flashes of light.
Some flashes came with food. Some did not. Then the birds got d-amphetamine to see if the drug made the flashes more powerful.
What they found
The drug did not boost the flashes. Birds pecked the same whether the light had been paired with food or not.
Instead, amphetamine just flattened the usual scalloped pattern you see on fixed-interval schedules.
How this fits with other research
Bordi et al. (1990) also gave pigeons d-amphetamine on fixed-interval schedules. They saw almost no change in pecking or movement. The two studies line up: the drug leaves pigeon operant behavior cold.
Dove (1976) found tiny, mixed effects when pigeons pressed a treadle to avoid shock. Again, d-amphetamine did little, matching the null result here.
Together, three pigeon labs show the same story: d-amphetamine does not strengthen operant responding the way it does in rats or humans.
Why it matters
If you use drug models to predict reinforcement effects, remember the species. A stimulus that pumps up responding in rats may do nothing in pigeons after amphetamine. When you design second-order schedules for other animals, do not count on the drug to magnify conditioned reinforcers. Test first, then trust.
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Join Free →If you use brief stimuli as reinforcers with pigeons, do not expect amphetamine to make them more powerful—measure baseline first.
02At a glance
03Original abstract
Three pigeons were studied under a multiple schedule in which pecks in each component were reinforced according to a variable-interval 120-s second-order schedule with fixed-interval 60-s units. In the first component of the multiple schedule, the completion of a fixed interval produced either food or a 4-s change in key color plus houselight illumination. In the second component an identical schedule was in effect, but the stimulus was a 0.3-s change in key color. Both long and short brief stimuli were not paired with food presentations in Conditions 1 and 3 and were paired with food in Condition 2. There were no consistent differences in response patterns under paired and nonpaired brief-stimulus conditions when the stimulus was a 4-s change in key color accompanied by houselight illumination. However, pairing the 0.3-s key-color change with food presentations resulted in higher indices of curvature and lower response rates in the early segments of the fixed interval than when the stimulus was not paired with food presentations. Low doses of d-amphetamine (0.3 and 1 mg/kg) produced small and inconsistent increases in overall response rates, and higher doses (3 and 10 mg/kg) decreased overall response rates. d-Amphetamine altered response patterns within fixed intervals by decreasing the indices of curvature and increasing response rates in the early segments of the fixed interval. Response rates and patterns under paired and nonpaired brief-stimulus conditions were not differentially affected by d-amphetamine. Thus, evidence for the enhancement of the conditioned reinforcement effects of psychomotor stimulant drugs was not found with the second-order schedules used in the present study.
Journal of the experimental analysis of behavior, 1991 · doi:10.1901/jeab.1991.56-289