The long-term, general objective of the work is to study the role of the brain in learning. The major approach is to compare the learning of different species in an attempt to correlate functional differences with dfferences in brain structure. Another is to compare the learning of animals with surgically altered brains. The more specific, immediate objectives are to continue the study of learning in fish, turtles, pigeons and rats in simple instrumental situations with a focus on parameters of reinforcement and an emphasis on the various roles played by reinforcement and nonreinforcement in the learning and control of intrumental behavior, and, to begin some work on the effects of brain lesions in turtles in an attempt to provide further information about the ancestral origins of mammalian behavior.