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Sustainable dietary choices improved by reflection before a nudge in an online experiment

Nature Sustainability volume 6, pages 1632–1642 (2023)Cite this article

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Abstract

Current food choices have a high carbon footprint and are incompatible with climate goals. Transitioning to more environmentally friendly diets is therefore important. Behavioural ‘nudges’ have been widely used to reduce meat-based food demand, subtly altering choice presentation without banning or raising costs. However, scaling up nudges has proven challenging, sometimes raising ethical concerns. To address this, behavioural science proposes empowering individuals to reflect on their choices, fostering meaningful and more environmentally-friendly behavioural changes. In an experimental study with 3,074 UK participants, we compared three agency-enhancing tools (‘boost’, ‘think’ and ‘nudge+’) with classic nudges (opt-out default and labelling) to promote sustainable dietary intentions. All behavioural interventions increased intentions for sustainable foods but encouraging reflection on dietary preferences before defaulting people into greener diets yielded the best results. Adding a pledge before the default nudge, as in nudge+ (pledge+ default), additionally reduced emissions from intended orders of meals by 40%. Our research suggests that food companies can enhance their sustainability efforts by prompting customers to think before nudging them into consuming more sustainable food.

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Fig. 1: Average emissions over intended meal orders across the ten experimental conditions (N = 3,009).
Fig. 2: Average treatment effect on emissions from meal orders compared to the ‘Nudge+ 3 (pledge+default)’ experimental condition.
Fig. 3: Average donations across the ten experimental conditions (N = 3,009).

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Data availability

The datasets generated by the survey research during and/or analysed during the current study are available in Figshare at https://doi.org/10.6084/m9.figshare.23536983.

Code availability

The analytic codes used for data cleaning and analysis during the current study are available in OSF at https://osf.io/5by4k/?view_only=7011ecec70f94772b51a59f965c40a67.

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Acknowledgements

We thank colleagues at LSE (Department of Geography and Environment, The Grantham Research Institute on Climate Change and the Environment, Department of Psychological and Behavioural Sciences) and VU Amsterdam; R. Hertwig, T. Grüne-Yanoff, A. Schulze-Tilling and J. Picard for their feedback on earlier versions of the manuscript; the organizers and attendees of the following conferences, where the findings of this paper were presented: Royal Economic Society, University College Dublin, Annual Conference on Economics and Public Policy (Jindal School of Government and Public Policy), UK–China Workshop on Energy and Climate Change Economics (UCL and BIT), LSE Environmental Economics and Policy Seminar Series, OSWEET Seminar Series 2021 on Environment, Behaviour and Experiments, Brunel University (Health Economics and Public Policy seminar series), Max Plank Institute Berlin (Adaptive Rationality Centre), University of Birmingham (Department of Economics: TEDE and BEADS research group), Yale University on Climate and Food (GAUC 2021), University of Exeter Business School LEEP Seminar 2021, LSE Economic Geography Seminar 2021, UK Network of Environmental Economists Webinar Series 2021, SABE-IAREP 2021, Grantham Research Institute Behavioural Group, and the World Bank (The Mind and Development Unit). M.M.G. acknowledges funding support from the Department of Psychological and Behavioural Science, LSE. P.J. acknowledges funding support from the Department of Political Economy, King’s College London. S.M. acknowledges funding support from the Department of Geography and Environment, LSE.

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Authors and Affiliations

  1. Institute for Environmental Studies, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands

    Sanchayan Banerjee

  2. Department of Geography and Environment, London School of Economics and Political Science, London, UK

    Sanchayan Banerjee & Susana Mourato

  3. Department of Psychological and Behavioural Science, London School of Economics and Political Science, London, UK

    Matteo M. Galizzi

  4. Department of Political Economy, King’s College London, London, UK

    Peter John

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Contributions

S.B. conceptualized the project, curated data, conducted formal analysis, conducted investigations, developed the methodology, administered the project, procured resources, developed software, performed visualization and wrote the original draft. S.B., M.M.G., P.J. and S.M. contributed to funding acquisition, project supervision, validation, and review and editing of the manuscript.

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Correspondence to Sanchayan Banerjee.

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Nature Sustainability thanks Joshua Tasoff, Andrew Jalil and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Figs. 1–17, and Tables 1 and 2.

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Banerjee, S., Galizzi, M.M., John, P. et al. Sustainable dietary choices improved by reflection before a nudge in an online experiment. Nat Sustain 6, 1632–1642 (2023). https://doi.org/10.1038/s41893-023-01235-0

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