Rational learners and parochial norms

Abstract

Parochial norms are narrow in social scope, meaning they apply to certain groups but not to others. Accounts of norm acquisition typically invoke tribal biases: from an early age, people assume a group's behavioral regularities are prescribed and bounded by mere group membership. However, another possibility is rational learning: given the available evidence, people infer the social scope of norms in statistically appropriate ways. With this paper, we introduce a rational learning account of parochial norm acquisition and test a unique prediction that it makes. In one study with adults (N = 480) and one study with children ages 5- to 8-years-old (N = 120), participants viewed violations of a novel rule sampled from one of two unfamiliar social groups. We found that adults judgments of social scope – whether the rule applied only to the sampled group (parochial scope), or other groups (inclusive scope) – were appropriately sensitive to the relevant features of their statistical evidence (Study 1). In children (Study 2) we found an age difference: 7- to 8-year-olds used statistical evidence to infer that norms were parochial or inclusive, whereas 5- to 6-year olds were overall inclusive regardless of statistical evidence. A Bayesian analysis shows a possible inclusivity bias: adults and children inferred inclusive rules more frequently than predicted by a naïve Bayesian model with unbiased priors. This work highlights that tribalist biases in social cognition are not necessary to explain the acquisition of parochial norms.