Using messages promoting descriptive norms to increase physical activity.

While it has been known for some time that what others do (i.e., normative behavior) can influence individual behavior, the effect of normative social influence on physical activity behavior has not been well established. The purpose of this study was to examine whether exposure to messages containing descriptive norm information about the prevalence of others' physical activity would affect individual physical activity behavior to a greater extent than exposure to nonnormative messages. Two independent studies were conducted. The first manipulated normative and nonnormative messages to examine effects on physical activity in office workers. Participants were assigned to one of four conditions (descriptive norm, health, appearance, or control) and received e-mail messages specific to their condition encouraging them to be active. It was hypothesized that participants in the descriptive norm condition would experience the greatest increase in physical activity, and the results supported this hypothesis for mild activity. A second study attempted to extend these results by examining the effect of descriptive norms on the activity behavior of university students, but no relationship was found. Typical activity levels and group identity with the reference group were suggested as possible explanations for the differing findings in these two studies.