The sense of should: A biologically-based framework for modeling social pressure

•We develop a model of social pressure, based on the metabolic costs of information.•We propose that conformity regulates the predictability of social environments.•We suggest that the experience of obligation stems from anticipated uncertainty.•We integrate disparate theories of mental inference with an embodied account.•We discuss the emergent consequences of others' expectations motivating behavior. What is social pressure, and how could it be adaptive to conform to others' expectations? Existing accounts highlight the importance of reputation and social sanctions. Yet, conformist behavior is multiply determined: sometimes, a person desires social regard, but at other times she feels obligated to behave a certain way, regardless of any reputational benefit—i.e. she feels a sense of should. We develop a formal model of this sense of should, beginning from a minimal set of biological premises: that the brain is predictive, that prediction error has a metabolic cost, and that metabolic costs are prospectively avoided. It follows that unpredictable environments impose metabolic costs, and in social environments these costs can be reduced by conforming to others' expectations. We elaborate on a sense of should's benefits and subjective experience, its likely developmental trajectory, and its relation to embodied mental inference. From this individualistic metabolic strategy, the emergent dynamics unify social phenomenon ranging from status quo biases, to communication and motivated cognition. We offer new solutions to long-studied problems (e.g. altruistic behavior), and show how compliance with arbitrary social practices is compelled without explicit sanctions. Social pressure may provide a foundation in individuals on which societies can be built.