Effects of d-amphetamine, diazepam, and pentobarbital on the schedule-controlled pecking and locomotor activity of pigeons.
Diazepam and pentobarbital raise key pecks but lower movement in pigeons, while d-amphetamine does almost nothing.
01Research in Context
What this study did
Scientists gave pigeons three drugs: d-amphetamine, diazepam, and pentobarbital.
The birds pecked a key on a fixed-interval schedule while the team also counted how much they moved around.
Each drug session was compared with baseline days to see how the chemicals changed both work and walking.
What they found
Diazepam and pentobarbital made the pigeons peck more, but they walked less.
D-amphetamine barely touched either pecking or activity.
The results show that calming drugs can boost operant output while cutting general movement.
How this fits with other research
Dove (1976) saw the same drugs in pigeons, but the birds pressed a treadle to avoid shock.
In that older study pentobarbital cut responding, not raised it.
The difference is the task: shock avoidance makes pentobarbital slow the birds down, while simple key pecking lets the drug release more responses.
Cohen (1991) also gave d-amphetamine to pigeons and found flat effects, matching the null result here.
Together the papers say amphetamine does little in pigeon operant work, while barbiturate effects flip with the situation.
Why it matters
If you run pharmacology sessions with animal models, expect the same drug to act differently when the contingency changes.
Use simple schedules when you want to see rate increases, and avoid aversive setups if you need steady baseline counts.
Always track both the target response and general activity; a calm bird may peck more but move less, and you will miss the trade-off if you watch only one measure.
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Join Free →Plot both response rate and side activity next time you test any intervention; a rise in one can mask a drop in the other.
02At a glance
03Original abstract
Pigeons were trained on a variant of the autoshaping procedure devised by Matthews and Lerer (1987) in which a keylight stimulus ramp of increasing brightness signaled the passing of a 30-s interfood interval. This procedure generates two distinct behavioral components: key pecking and locomotor activity. The effects of three psychoactive drugs on these behavior classes were measured. d-Amphetamine had negligible effects on both types of behavior, whereas diazepam and pentobartital increased key pecking and decreased activity in a dose-dependent fashion. In Experiment 2, the possibility that drug effects were suppressed by excessively strong stimulus control exerted in Experiment 1 was tested by decreasing the discriminability of the stimulus ramp. The direction of the effects of diazepam and pentobarbital was the same as in Experiment 1 but the magnitude of the effects tended to be larger. The effects of d-amphetamine, however, remained quite small, suggesting that, under these conditions, locomotor activity and key pecking are less sensitive to d-amphetamine. In Experiments 3 and 4, key pecking was eliminated by removing the keylight. Reinforcers were presented at fixed intervals in Experiment 3 and at variable intervals in Experiment 4. The drug effects on activity observed in Experiments 1 and 2 disappeared in both Experiments 3 and 4. The results suggest that diazepam and pentobarbital affect activity indirectly by increasing key-pecking behavior, which, in turn, competitively decreases activity.
Journal of the experimental analysis of behavior, 1990 · doi:10.1901/jeab.1990.53-87