Effects of amphetamine-CNS depressant combinations and of other CNS stimulants in four-choice drug discriminations.
Four-choice drug discrimination shows pigeons can sort complex internal states with lab-grade precision.
01Research in Context
What this study did
Researchers taught pigeons to tell four drug states apart.
Birds pecked one of four keys after getting amphetamine, a depressant, both, or saline.
Correct picks earned grain; wrong picks turned the lights off.
What they found
The birds scored above 90 % correct on every drug cue.
Mixing stimulant and depressant created a new, readable cue.
The four-choice method caught tiny differences between novel compounds.
How this fits with other research
Rojahn et al. (1994) ran the same logic with people. Humans also sorted methamphetamine from pain medicine, showing the idea works across species.
Danitz et al. (2014) switched the task to Japanese quail and used Pavlovian cues instead of peck keys. Cocaine and nicotine still felt like meth to the birds, proving the method bends but does not break.
Bottjer et al. (1979) set the table decades earlier. Their pigeons learned faster when food predicted reward trials. Mi et al. swapped food cues for drug cues and kept the four-choice format, turning an old trick into a fine drug probe.
Why it matters
If pigeons can sort four internal states, your learners can sort four external ones. Try adding a fourth choice when you probe stimulus control. The study reminds us that sharp discrimination tools can reveal hidden blends, whether those blends are drug mixes or mixed prompts in a classroom.
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02At a glance
03Original abstract
Three pigeons were trained to discriminate among 5 mg/kg pentobarbital, 2 mg/kg amphetamine, a combination of these two drugs at these doses, and saline using a four-choice procedure (amphetamine-pentobarbital group). Three other pigeons were trained to discriminate among 5 mg/kg morphine, 2 mg/kg methamphetamine, a combination of these two drugs at these doses, and saline (methamphetamine-morphine group). After 10 to 13 months of training, the pigeons averaged more than 90% of their responses on the appropriate key during training sessions. In subsequent testing, dose-response curves were determined for the individual drugs, for a wide range of dose combinations of the training drugs, and for two drugs to which the pigeons had not been exposed previously (pseudoephedrine and nicotine). After low test doses of the training drugs, pigeons responded on the saline key. As the dose increased, responding on the key associated with that drug during training sessions increased. When training drugs were combined at doses that were not discriminable when given alone, responding occurred on the saline key. When a discriminable dose of one training drug was combined with a nondiscriminable dose of the other training drug, responding occurred on the key associated with the discriminable dose. When both drugs were given at discriminable doses, responding almost always occurred on the drug-combination key. The response-rate decreasing effects of pentobarbital and amphetamine were mutually antagonized when the drugs were combined, but the rate-decreasing effects of morphine and methamphetamine were not. After low doses of pseudoephedrine and nicotine, pigeons in both groups responded on the saline key. After higher doses of pseudoephedrine and nicotine, responding in the amphetamine-pentobarbital group occurred primarily on the amphetamine key. In the methamphetamine-morphine group, higher doses of pseudoephedrine and especially nicotine engendered more responding on the combination key than had occurred in the other group. The four-choice procedure can reveal subtle effects in the discrimination of individual drugs and drug combinations that are not apparent with procedures offering fewer response alternatives.
Journal of the experimental analysis of behavior, 2005 · doi:10.1901/jeab.2005.09-04