Results of an experiment with 45 female undergraduates demonstrate effects consistent with D. J. Bem's 1972 self-perception theory. Role playing was used as the vehicle through which self-perception occurred. It was hypothesized that within a perceived-choice paradigm, role playing an "upset" reaction (role playing-upset) to electric shocks would lead to subsequent decreases in pain and tolerance thresholds, whereas role playing a "calm" reaction (role playing-calm) would lead to subsequent increases. Ss underwent 3 series of electric shocks designed to measure pain and tolerance thresholds. The 1st shock series was a pretest and the 3rd series was a posttest. During the 2nd shock series, Ss were randomly assigned to 1 of 3 groups: role playing-upset, role playing-calm, or no role playing (control). The dependent pretest-posttest change measures revealed significant group differences relative to controls for the role-playing groups in directions supporting the hypotheses. A physiological measure suggested that the findings were not due to attention to internal information. Additionally, several correlations consistently indicated that the degree of manipulation during the 2nd series was significantly associated with the pretest-posttest changes. Results are discussed in terms of self-perception theory and clinical applications. (19 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)