Measuring substance-free and substance-related reinforcement in the natural environment.

The present study sought to provide further evidence for the validity of a modified version of the Pleasant Events Schedule (PES; D. J. MacPhillamy & P. M. Lewinsohn, 1982) designed to measure substance-free and substance-related reinforcement. A sample of 134 young adults completed the modified PES along with measures of substance use and quality of life. The results extend previous research on the modified PES in 3 ways: (a) Information regarding the relationships between substance-related reinforcement and substance use are expanded to include substance-use frequency, quantity, and related negative consequences; (b) relationships between substance-free reinforcement and non-substance-related variables are established; and (c) the distinctiveness of the substance-free and substance-related reinforcement scores is demonstrated. The utility of reinforcement surveys in the study of substance use is discussed, with special emphasis placed on possible treatment implications.