Norms with a purpose: Examining the effects of descriptive norms and outcome expectations on muscular endurance


Using normative messages to influence behaviour has been receiving increased attention in the activity setting, with descriptive norms (perception of what is commonly done) being associated with various forms of activity-related behaviour (Priebe & Spink, 2014; Spink et al., 2013).  Most studies examined in the activity setting have used focus theory (Cialdini et al., 1990) as their conceptual underpinning.  One of the main tenets of the theory suggests that norms will only influence behaviour if the norm is focal to the individual. While different procedures have been used to produce a normative focus (e.g., arousal), the use of a positive outcome expectation has not been examined. This study explored the influence of adding a positive outcome expectation to a descriptive norm on endurance behaviour. Thirty university students were randomly assigned to one of three conditions: control (n=10), descriptive norm (DN; n=10), or descriptive norm + outcome expectation (DN+OE, n=10), and asked to perform two plank exercises to maximal exertion separated by a 3-minute rest period. Between planks, those in the DN were given a message that most others actually held their second plank longer; DN+OE received the same message plus were told those who did so were the most motivated and committed; control received no message.  Controlling for the initial plank time, ANCOVA results revealed a significant main effect for condition,  p < 0.02, ηp2 = 0.27, in which control participants held their second plank less than those receiving the DN (adj Cohen’s d=.83) and DN+OE (adj d=1.29) message. Further, a medium effect was found between the DN+OE and DN condition (adj d=.43), with the former having the highest plank time. If replicated, these results suggest that adding a positive outcome expectation to a normative message may produce a stronger normative focus resulting in a larger influence on activity behaviour.