Motivational role of social reinforcement in dog-man relations.

Lesions of dorsomedial amygdala (DMA) or lateral hypothalamus (LH) produced prominent impairment of the alimentary behavior in dogs. Besides, various behavioral responses, including social, were depressed. To evaluate whether these changes were either specific for alimentary disturbances or dependent on changes in the general reward system, another type of reward, i.e. social contact with experimenter as a reinforcement for several motor responses was introduced. Damage of amygdalo-hypothalamic system, which produced a syndrome of depression, also impaired socially reinforced responses. This impairment lasted much longer then decrease of food intake. Therefore it was assumed that DMA and LH damage produced impairment not limited to alimentary mechanisms, but involving various aspects of positive motivational system and in particular including the social behavior during man-dog relations. Taking into account various theories of reinforcement in instrumental learning the authors are inclined towards a hedonistic theory of reward.