Drug states as discriminative stimuli in a flavor-aversion learning experiment.

Injection of poison into rats after they drank in the presence of stimulus compounds of a drug state and a flavor resulted in little stimulus control by the drug state. In Experiment 1, half of the rats were poisoned after drinking salt water while stimulated with amphetamine and after drinking sugar water while sedated with pentobarbital, but they were not poisoned after salt-pentobarbital or sugar-amphetamine combinations. The other half were subjected to counterbalanced procedures. In abstract language, poisoning occurred after AX and BY stimulus combinations but did not occur after AY and BX combinations. In Experiment 2A, rats were poisoned only after consuming a particular flavored solution (salt or vinegar) in a particular state (pentobarbital or undrugged); that is, if AX was poisoned, BX, BY, and AY were experienced without poisoning. There was complete counterbalancing of flavors and drug states. Experiment 2B was similar except that amphetamine was used instead of pentobarbital. In both experiments, there was some discrimination learning based on the drug state, gut it was extremely weak.