How tough should the love be? The effect of varying levels of descriptive norm feedback on performance and maximum heart rate during an exercise task.

Growing evidence suggests that manipulations of descriptive norms-perceptions of the typical behaviours of others-can affect people's exertion and performance during exercise tasks. However, no research has systematically varied the extent to which people are told they are below the norm with a view to understanding how this aspect of norm feedback affects the strength of its effects on exertion, performance, or other outcomes. In a pre-registered experiment (N = 105) with a pre-post between-subjects design and three conditions, we compared the effect of norm messages indicating that participants had performed 10%, 30%, or 50% below the norm on an exercise task. Participants first completed a baseline trial of a timed maximum effort wall sit. Then, prior to and during Trial 2, participants received feedback that their task performance was below average by one of the three amounts. Participants in the 50% condition demonstrated greater increases in their wall sit performance from Trial 1 to Trial 2 than participants in the 10% and 30% conditions. There were no significant differences between conditions in changes in maximum heart rate (a proxy for participants' exertion). The effects of the norm feedback on performance were not underpinned by changes in either participants' task motivation or perceived similarity to the norm reference group. Results suggest that feedback indicating a high discrepancy between one's own performance and the norm facilitates greater performance improvements on a physically demanding task than less discrepant (and more attainable) feedback. Further research is required to understand the mechanisms underpinning this effect.