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Friday, March 17, 2023

Rational learners and parochial norms

Partington, S. Nichols, S., & Kushnir, T.
Volume 233, April 2023, 105366


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 na├»ve Bayesian model with unbiased priors. This work highlights that tribalist biases in social cognition are not necessary to explain the acquisition of parochial norms.

From the General discussion

The widespread prevalence of parochial norms across history and cultures have led some to suggest parochialism is itself a human universal (Clark et al., 2019; Greene, 2013) in part owing to evolved, group-based biases in social norm acquisition (Chalik & Rhodes, 2020; Chudek & Henrich, 2011; Roberts et al., 2017). In this paper, we investigated whether a rational learning process can also explain this phenomenon. In Study 1, we found that adults can acquire distinctions of social scope in a statistically appropriate manner, and this finding was robust across two forms of measurement (rule judgments and open response). In Study 2, older children displayed the adult-like statistical sensitivity in their rule judgments, and even younger children did so in their open responses. Computational analyses suggests that rule judgments were inclusively biased: compared to an unbiased Bayesian learner, children tended to assume that novel rules apply to everyone in a candidate population. Adults also displayed an inclusive bias, albeit to a lesser extent than children.

Broadly, these findings suggest that rational learning processes can indeed explain the acquisition of parochial norms and highlight an important sense in which children's norm learning can be biased in the opposite direction of tribalism. At the least, the finding that children and adults are inclusively biased serves as an existence proof that deep-rooted tribal biases in social learning are not necessary to explain the acquisition of parochial norms. Rather, if children and adults are rational learners, they can acquire a parochial norm when presented with evidence that is consistent with parochialism. However, tribalism can still play a role in norm acquisition, for example, by influencing the sort of evidence that adults seek out, or the evidence to which children are exposed.