Conformity to continuous and discrete ordinal traits

TL;DR

This paper develops models for conformity to ordinal cultural traits, both discrete and continuous, showing that such conformity can maintain diversity and lead to polarization, contrasting with previous models focused on nominal traits.

Contribution

Introduces new models of conformity for ordinal traits, including a novel metric called $k$-dispersal, and demonstrates their implications through simulations.

Findings

Conformity to ordinal traits can sustain trait diversity over generations.

Anti-conformity may lead to polarization.

Models challenge the idea that conformity always homogenizes populations.

Abstract

Models of conformity and anti-conformity have typically focused on cultural traits with nominal (unordered) variants, such as baby names, strategies (cooperate/defect), or the presence/absence of an innovation. There have been fewer studies of conformity to "ordinal" cultural traits with ordered variants, such as level of cooperation (low to high) or fraction of time spent on a task (0 to 1). In these latter studies, conformity is conceptualized as a preference for the mean trait value in a population even if no members of the population have variants near this mean; e.g., 50% of the population has variant 0 and 50% has variant 1, producing a mean of 0.5. Here, we introduce models of conformity to ordinal traits, which can be either discrete or continuous and linear (with minimum and maximum values) or circular (without boundaries). In these models, conformists prefer to adopt more popular cultural variants, even if these variants are far from the population mean. To measure a variant's "popularity" in cases where no two individuals share precisely the same variant on a continuum, we introduce a metric called $k$-dispersal; this takes into account a variant's distance to its $k$ closest neighbors, with more "popular" variants having lower distances to their neighbors. We demonstrate through simulations that conformity to ordinal traits need not produce a homogeneous population, as has previously been claimed. Under some combinations of parameter values, conformity sustains substantial trait variation over many generations. Anti-conformist transmission may produce high levels of polarization.