Research

Job Market Paper

Picard, J. & Banerjee, S. (2022). Estimating the Side Effects of Green Nudges (available here)

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 that social norm nudges are effective but crowd out people's willingness to do more.

Published works

Banerjee, S. & Picard, J. (2023). Thinking Through Norms Can Make Them More Effective. Experimental Evidence on Reflective Climate Policies in the UK (Journal of Behavioral and Experimental Economics, full text here)

Adopting low-carbon diets is important to meet our climate goals. Prior experimental evidence suggests green nudges help people adopt such diets, more so when they are encouraged to think through them. In this paper, we re-evaluate this role of reflection in a “social norm” nudge to promote intentions for climate-friendly diets in the United Kingdom. Using 5,555 British respondents, we find the social norm nudge increases meal order intentions for low-carbon diets versus the control condition. Asking people to reveal their personal dietary norms, after exposing them to these social norms (“lower-order nudge+”), does not produce any measurable change compared to the nudge. However, when people are subsequently encouraged to think and pledge to climate-friendly diets (“higher-order nudge+”), the effectiveness of the social norm nudge increases by 90% or more.

Registered reports 

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Picard, J., Kobrich, A., Schobin, J. (2023). Experimental evidence on the role of framing, difficulty and domain similarity in shaping behavioral spillovers (in-principle acceptance, Scientific Reports)

We develop a between-subject online experiment to study when encouraging a climate-friendly behavior spur or hamper further engagement for the environmental cause. First, respondents read a newspaper article dealing with a first pro-environmental behavior (helping scientists as a new form of climate activism). Second, participants choose whether to undertake the behavior emphasized. Third, respondents are offered to do a second, subsequent, pro-environmental behavior (signing a petition to call for political action against climate change). In study 1, we manipulate the narrative of the newspaper articles. It either condemns individual inaction, or encourage being pro-environmental. We compare these narratives against a neutral narrative (control) and an article dealing with an unrelated subject (placebo). In study 2, we investigate how the difficulty of the first pro-environmental behavior moderates behavioral spillovers. In study 3, we test the moderating effects of behavioral distance, i.e. the domain-similarity of the two subsequent behaviors.

Picard, J., Balmford, B., Banerjee, S., Groom, B. (2021). Pro-social motives and the Effectiveness of matching subsidies

Research shows that subsidising donations increases support for charitable causes but crowds out donations from those who would have given anyway. We investigate whether pro-social motives drive these effects. We consider two types of pro-social motives: deontological (“I support the cause for itself”) and consequential (“I support the cause for the benefits it provides to society”). We design a within-between-subject experiment in which respondents give to biodiversity conservation charities. In the within dimension, we vary the subsidy to estimate the elasticity of respondents’ donations with the subsidy. In the between dimension, we prompt respondents to think about the risk of biodiversity depletion with different framing. Namely, we either emphasise the right to live of species (deontological framing), their usefulness for humans (consequential framing), or stays neutral (control). We investigate whether the elasticity varies with the framing. 


Working Papers

Picard, J. (2021). A Model of Pro-Social Policies (full text here)

We act pro-socially whenever we forgo immediate hedonic pleasure to do what is right (e.g., being pro-environmental, helping others). I model pro-social decisions as either intrinsically motivated (done as an end to themselves) or extrinsically motivated (done as a means to an end). Individuals' pro-social nature evolves with the context and their past choices. This model reconciles several contradicting findings in the social psychology literature. It also provides micro-foundations to behavioural spillover effects, backfiring effects, and the heterogeneity of pro-social policies.

Picard, J., Banerjee, S. (upcoming). A clash of norms? Experimental evaluation of cultural framing in promoting low-carbon diets

Vegetarian diets can reduce global ecological costs. Yet meat continues to be culturally dominant, especially in the West. Does culture hamper the adoption of vegetarian diets? In an online experiment, we observed the intentions of 2,775 English participants to choose vegetarian food. We causally test if framing food options with culturally familiar names alters the effectiveness of a nudge promoting vegetarianism. Facing culturally familiar food does not change the effect of the nudge. However, exploratory analyses reveal that participants ask for lower monetary compensation for being forced to choose vegetarian food when it is culturally framed. Thus, welfare losses of hard policies, like bans, may be lower when alternative options look familiar.