# Biases in cultural transmission of information about a minimal ingroup

## TL;DR

This study shows how group membership influences how we pass on information about personality traits, favoring positive and neutral traits of our own group.

## Contribution

The study identifies a selective bias in cultural transmission based on minimal group membership and trait valence.

## Key findings

- Transmission of positive and neutral traits decreased less for ingroup compared to outgroup.
- Negative traits showed no significant difference in transmission between groups.
- The observed bias is attributed to an ingroup-positivity bias and higher transmission accuracy for ingroup traits.

## Abstract

Group membership and our beliefs about the groups we belong to are the building blocks of our social and cultural identity. Here, we investigated whether transmission of information about how often different personality traits occur in a minimal ingroup and outgroup results in distinct patterns of cultural evolution. Participants transmitted information about the occurrence of positive, negative and neutral traits to other participants in linear transmission chains. First, we found a general tendency for occurrence of all traits to decrease across generations. However, our control experiment revealed that this general decrease was not specific to transmission of information about traits but represented a low-level response bias. Critically, this decrease across generations was smaller when participants were transmitting information about ingroup than outgroup traits, but only for positive and neutral traits. No significant difference emerged for negative traits. Together, these results show that minimal group membership can selectively bias transmission of information about ingroup and outgroup. We propose that this results from two processes: an ingroup-positivity bias and higher accuracy when transmitting ingroup-related information. Overall, our study provides an example of how examining mechanisms of cultural transmission can elucidate our understanding of processes of formation and evolution of social-cultural identity.

The online version contains supplementary material available at 10.1038/s41598-026-35241-x.