If animals are repeatedly administered alcohol in the presence of distinctive cues in one location and saline in a different location with different cues, one can then test the animal in an environment where both locations are available. If the animal elects to spend the majority of the time in the drug-paired environment, one infers that it found the subjective experience of the drug pleasant, even though it is not under the influence of the drug during the test. One study compared P and NP rats in a place conditioning paradigm that resulted in a conditioned place aversion (CPA). Aversion of the alcohol-paired location was less pronounced in P rats, suggesting that they were less sensitive to the aversive stimulus effects of alcohol than NP rats (Stewart et al. 1996). On the other hand, in another study, msP rats showed a pronounced conditioned place preference (CPP) (Ciccocioppo et al. 1999). It should be noted that the msP line has no direct comparator line, selected for low drinking—nonetheless, the direction of the effect was opposite to that seen in the P
