The effects of feedback and induced intrapersonal expectancy on behavior change



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The effects of feedback and an induced expectancy of success were assessed in this study. The feedback manipulation was partially intended as a replication of earlier studies by Evans, et al. (1975) and Williams (1974). The expectancy manipulation was based on the work of Rosenthal in experimenter bias. The present study was part of a larger dental hygiene project designed to test the effectiveness of different tools for the disclosure of bacterial plaque. Staff members of a large medical school (N = 149) were used as subjects. Experimental and control groups from the larger project were combined into a feedback group, a non-feedback group, and an expectancy group. All subjects were instructed in proper dental hygiene and were provided with necessary supplies. Those subjects in the feedback conditions were examined four times and received computer-generated reports of their progress after each examination. Non-feedback subjects were examined only twice, at the beginning and the end of the experiment and did not receive feedback until the experiment was completed. Subjects in the expectancy group received feedback and a special hand-typed, message stating that based on past results, exceptional performance was expected of them. It was hypothesized that feedback subjects would improve more than non-feedback subjects and that expectancy subjects would improve more than feedback subjects. Neither hypothesis was supported, although the expectancy subjects appeared to improve faster than other subjects in the study. A number of problems that occurred within the study are discussed.