The next Economics Seminar of Paris-Saclay will take place on Thursday, February 1st from 12h15 to 13h15, in room Gaudemet.

Julien Picard (London School of Economics) will present “Behavioural Spillovers Unpacked: Estimating the Side Effects of Social Norm Nudges”.

Abstract: Fighting the climate crisis requires changing many aspects of our consumption habits. Previous studies show that a first pro-environmental action can lead to another. But does this spillover effect persist when nudges foster the initial action? We model the mechanisms leading nudges to alter such behavioural spillovers. In an online experiment (n=2775), we test if encouraging vegetarianism with a social norm nudge alters environmental donations. The nudge is effective in increasing intentions to choose vegetarian food. Using machine learning, we find that a subgroup drives this effect. We also see a positive spillover effect: choosing vegetarian food increases donations. However, the nudge crowds out this spillover effect for the subgroup identified with machine learning. Our results suggest no free lunch: when the nudge works in increasing vegetarian choices, this is at the cost of crowding out people’s willingness to do more.

Link to the seminar web page: