Understanding the setback effect in everyday self‐regulation.

People experience minor instances of self‐regulation failure, i.e., setbacks. While in itself trivial, a single setback may trigger a maladaptive chain of cognitions and emotions leading to more self‐regulation failure. In the present article, we investigated (a) whether the experience of a setback indeed increases the chance of subsequent failure, and (b) what psychological mechanisms underly this effect. We conducted three studies in the context of eating behaviour, exercising, and saving. At T1 we assessed participants intentions, self‐efficacy, and perceived usefulness to self‐regulate in response to a recent setback (versus an instance of self‐regulation success). At T2 we assessed subsequent self‐regulation failure and success using retrospective recall. Experiencing a setback increased the likelihood of subsequent failure and decreased the chances of subsequent success. Our results most consistently highlight a decrease in self‐efficacy as an underlying mechanism, and therefore as a promising target for interventions to prevent the setback effect from occurring. [ABSTRACT FROM AUTHOR]