DEMAND FOR SOCIAL CONTACT IN RATS: TOWARD A QUANTITATIVE ANALYSIS OF SOCIAL REINFORCEMENT VALUE

Rats were studied in social-release procedures, in which lever presses by one rat released a second rat from a tube restraint for a period of social interaction. Both the fixed-ratio price and the duration of social contact were varied systematically on a within-subject basis, generating a total of 27 demand functions across six subjects. Overall, the data were well accounted for by the essential value model (96% VAF), supporting a social reinforcement view, according to which social-release behavior is maintained by social contact with another rat. Response rates and parameter fitswere comparable in 25-min and 120-min sessions, showing little evidence of satiation.Overall, the findings suggest that socially-reinforced behavior shares functionalproperties with other reinforcers, and illustrate a promising set of methods for quantifying social reinforcement value.