| The purpose of this study was to examine the efficacy of Köhler motivation gain principles (i.e. indispensability, social comparison) for increasing physical activity under free-living conditions. This field experiment employed a 2 (gender) x 3 (condition: individual, coactive, conjunctive) x 8 (weeks) factorial design with repeated measures on the last factor. After a 1-week assessment of baseline habitual physical activity (using Sensewear Armband monitors, expressed as energy expenditure), participants had a brief orientation in the lab where they learned safe strategies for increasing their physical activity, appropriate for stage of participant readiness for change. After the orientation, participants were randomly assigned to one of the three conditions and their task was to increase their physical activity over a 7-week period. All subjects received performance feedback on their energy expenditure each week. Participants in the partner conditions also received performance feedback on their partner's energy expenditure, which was manipulated to be always greater than the subject's. Planned contrasts showed that partner conditions initially decreased, F (1,17) = 7.92, p = .01, but maintained a steady level of physical activity (and approached a significant positive linear trend) over the last 3 weeks of the study, F (1, 16) = 4.12, p = .06. Physical activity for subjects in the individual condition did not change, F (6, 18) = 1.40, p = .27. Limitations, implications, and directions for future research are discussed. |
