Three groups of rats (A, B, C) were trained in a T-maze discriminate between drug-and control solution-induced internal discriminative stimuli. The drugs used to induce discriminative stimuli were: delta 9-THC, 5.0 mg/kg (Group A); ethanol, 1.2 g/kg (Group B), and amphetamine, 1.0 mg/kg(Group C). After discrimination acquisition several drugs were tested for generalization in each group. Group...