In bar pressing tests with either food or water as the motivator, tegmental operatees were deficient by comparison with normals (p <.002 for tests using a continuous-reinforcement schedule and p <.002 for tests using increasing ratios of reinforcement). However, in a straight alley, with food as the motivator, tegmental operatees ran faster than normals (p <.02); and, in situations in which food and water were freely available, significant differences were not found between tegmental operatees and normals. These data suggest that the amount of work involved in securing food may be a crucial variable. Operated controls with fornix-hippocampal commissure lesions performed as well as normals on some tasks and significantly better than normals and tegmental operatees on other tasks. (PsycINFO Database Record (c) 2006 APA, all rights reserved)