Behavioural public policies for the social brain

Abstract Behavioural public policy is increasingly interested in scaling-up experimental insights to deliver systemic changes. Recent evidence shows some forms of individual behaviour change, such as nudging, are limited in scale. We argue that we can scale-up individual behaviour change by accounting for nuanced social complexities in which human responses to behavioural public policies are situated. We introduce the idea of the ‘social brain’, as a construct to help practitioners and policymakers facilitate a greater social transmission of welfare-improving behaviours. The social brain is a collection of individual human brains, who are connected to other human brains through ‘social cues’, and who are affected by the material and immaterial properties of the physical environment in which they are situated (‘social complex’). Ignoring these cues and the social complex runs the risk of fostering localised behavioural changes, through individual actors, which are neither scalable nor lasting. We identify pathways to facilitate changes in the social brain: either through path dependencies or critical mass shifts in individual behaviours, moderated by the brain's property of social cohesion and multiplicity of situational and dispositional factors. In this way, behavioural changes stimulated in one part of the social brain can reach other parts and evolve dynamically. We recommend designing public policies that engage different parts of the social brain.