Abstract
Two experiments are described showing that a pentobarbital versus saline discrimination can be differentially conditioned to different external contexts. In experiment 1, rats differentiated two T-shaped mazes (one water maze and one electrified maze). In experiment 2, the external stimuli were the presence and absence of light during training in the electrified T-maze. These experiments constitute the first examples where a single drug versus nondrug discrimination has been conditioned to different external contexts requiring an opposite response pattern by the same animal. The data are in accordance with a stimulus interpretation of drug discrimination learning.