As a physiological technique, electrical stimulation of the brain dates from the classic studies of Fritsch and Hitzig (24) on the motor cortex of the dog. The use of this technique in behavioral research, however, is a more recent development. Since the pioneer studies of Loucks (62, 63, 64), psychologists have evinced sporadic interest in electrical stimulation of the brain as an important research tool in elucidating the neural mechanisms underlying behavior. Recent findings in neurophysiology, and advances in electrophysiological methodology, have led to a resurgence of this interest. Hess's studies of the diencephalon (41,42,43,44,45,46), 1 The following abbreviations have been