What’s the Net Benefit of a Nudge? Prosocial Defaults Affect Both Targeted and Subsequent Behaviour

Although nudging is increasingly recognized as an important policy tool for encouraging prosocial behaviour, there is little empirical evidence about downstream effects of such interventions. In five experiments, we explore behavioural spillover from the most well-known and used nudge: the default nudge. Analysing the combined dataset of approximately 10,000 participants, we find that participants subjected to a prosocial default at an initial monetary choice behaved more prosocially at a subsequent effortful task compared to participants initially subjected to a proself default. The effect stems from those who resisted the default nudge and compensated their initial proself choice through behaving prosocially afterwards, which is suggestive of a moral cleansing mechanism. While behavioural spillover effects from default nudges appear to be small, they are still potentially consequential due to the scalability of nudge interventions.