Two procedures establishing preference for oral cocaine and lidocaine solutions which do not use an associative history with a reinforcer.

Groups of rats were exposed to daily, 3-h, fixed-time 1-min food-pellet delivery sessions, a procedure that produces overdrinking (schedule-induced polydipsia, SIP). Previous research demonstrated that rats drinking a drug or non-drug solution come to prefer that solution to water if the solution had (a) a past association with either a highly acceptable vehicle (e.g. glucose/saccharin), or (b) allowed rats to eschew drinking an unacceptable solution under SIP conditions. The present experiments show that under the solution-avoidance procedure, preference for a concurrent, alternative solution (0.19 mg/ml lidocaine or 0.24 mg/ml cocaine) occurred when a concentrated quinine solution alternative was either abruptly removed or faded. A concentrated cocaine solution, however, was minimally effective in producing a preference for 0.19 mg/ml lidocaine to water when cocaine concentration was faded. Flavor/nutrient-conditioning (conditioned reinforcement) and solution-eschewing (avoidance) procedures may throw light on the kinds of historical situations that determine the genesis of stable preferences for drugs and other substances.