Decoding the Dynamics of Cultural Change: A Cultural Evolution Approach to the Psychology of Acculturation.

PUBLIC ABSTRACT: Acculturation describes the cultural and psychological changes resulting from intercultural contact. Here, we use concepts from "cultural evolution" to better understand the processes of acculturation. Cultural evolution researchers view cultural change as an evolutionary process, allowing them to borrow tools and methods from biology. Cultural evolutionary mechanisms such as conformity (copying the numerical majority), anti-conformity (copying the numerical minority), prestige bias (copying famous individuals), payoff bias (copying successful people), and vertical cultural transmission (copying your parents) can cause people to adopt elements from other cultures and/or conserve their cultural heritage. We explore how these transmission mechanisms might create distinct acculturation strategies, shaping cultural change and diversity over the long-term. This theoretical integration can pave the way for a more sophisticated understanding of the pervasive cultural shifts occurring in many ethnically diverse societies, notably by identifying conditions that empower minority-group members, often marginalized, to significantly influence the majority group and society.

Private but not social information validity modulates social conformity bias.

It is well established that human behaviors are susceptible to others' opinions. However, optimal decision theory mandates choices be made upon the estimated validities of different information sources and little is known about whether and how people could wean themselves off social conformity bias, especially when the social signals are uninformative. Here, we asked subjects to participate in a probabilistic urn guessing task based on their private information as well as observed choices from their partners. Specifically, we manipulated the information validity of these two sources such that only the private evidence was informative. Across trials, social conformity declined, manifested by the increased influence of the private evidence but steady effect of social information. Correspondingly, we found dorsomedial prefrontal cortex (dmPFC) was involved in detecting the conflict of private and social information and conforming to social signal whereas striatum was responsible for selectively updating the influence of private (but not social) evidence contingent on its inferred validity. Furthermore, functional coupling between striatum and dmPFC predicted the resistance toward the influence of social information. Together, these results may provide a mechanistic account of how the conformity bias toward uninformative social information can be remedied.

Adoption of outgroup norms provides evidence for social transmission in perinatal care practices among rural Namibian women.

BACKGROUND AND OBJECTIVES: How do new ideas spread in social groups? We apply the framework of cultural evolution theory to examine what drives change in perinatal care norms among Himba women in the Kunene region of Namibia. Access to formal medical care is on the rise in this region, and medical workers regularly visit communities to promote WHO-recommended perinatal care practices. This study investigates how various forms of social transmission affect women's uptake of medical recommendations concerning perinatal care. METHODOLOGY: Based on interviews with one hundred Himba mothers, we used Bayesian multi-level logistical regression models to examine how perceptions of group preferences, prestige ascribed to outgroup conformers, interaction with the outgroup and access to resources affect norm adoption. RESULTS: Women who perceive medical recommendations as common in their group prefer, plan and practice these recommendations more often themselves. We observed a shift toward medical recommendations regarding birth location and contraception use that was in line with conformity bias predictions. Practices that serve as cultural identity markers persist in the population. CONCLUSIONS AND IMPLICATIONS: Norm changes, and the cultural evolutionary processes that can lead to them, are not uniform, either in process or pace. Empirical studies like this one provide important examples of how these changes reflect local culture and circumstance and are critical for better understanding the models that currently predominate in cultural evolution work. These cases can also help bridge the gap between evolutionary anthropology and public health by demonstrating where promotion and prevention campaigns might be most effective. LAY SUMMARY: The recent promotion of WHO-recommended perinatal care practices in Namibia provides an opportunity to empirically study norm change using a cultural evolution framework. We found women adopt medical recommendations when they believe these are common in their social group. Local norms that were not discouraged persisted in the study group.

Modelling the spread of innovation in wild birds.

We apply three plausible algorithms in agent-based computer simulations to recent experiments on social learning in wild birds. Although some of the phenomena are simulated by all three learning algorithms, several manifestations of social conformity bias are simulated by only the approximate majority (AM) algorithm, which has roots in chemistry, molecular biology and theoretical computer science. The simulations generate testable predictions and provide several explanatory insights into the diffusion of innovation through a population. The AM algorithm's success raises the possibility of its usefulness in studying group dynamics more generally, in several different scientific domains. Our differential-equation model matches simulation results and provides mathematical insights into the dynamics of these algorithms.

Social learning strategies in networked groups.

When making decisions, humans can observe many kinds of information about others' activities, but their effects on performance are not well understood. We investigated social learning strategies using a simple problem-solving task in which participants search a complex space, and each can view and imitate others' solutions. Results showed that participants combined multiple sources of information to guide learning, including payoffs of peers' solutions, popularity of solution elements among peers, similarity of peers' solutions to their own, and relative payoffs from individual exploration. Furthermore, performance was positively associated with imitation rates at both the individual and group levels. When peers' payoffs were hidden, popularity and similarity biases reversed, participants searched more broadly and randomly, and both quality and equity of exploration suffered. We conclude that when peers' solutions can be effectively compared, imitation does not simply permit scrounging, but it can also facilitate propagation of good solutions for further cumulative exploration.