Traditionalism mediates social learning: Biases in acceptance of novel health interventions among Himba pastoralists.

Background and objectives: Applying social learning biases to healthcare decision-making may help explain why some people decide not to adopt health interventions. Traits like market integration and traditionalism can shape social learning biases, particularly in small scale populations with little formal education and distrust of outgroup populations. This study investigates the role of these features on social learning biases across four different health interventions among Himba pastoralists of northern Namibia. Methodology: Using vignettes from 473 participants sampled in 16 communities, we compare three social learning biases (conformity, prestige bias, parochialism) in four novel healthcare interventions. Participants completed a set of questions to estimate traditionalism and market integration. Multilevel models compared the impact of these variables on the probability of adopting the healthcare interventions. Results: Across social learning biases, conformity showed the strongest effect on likelihood of adoption, whereas we found no difference in the prestige bias condition (compared to conformity). More market integrated participants were more likely to adopt interventions, whereas more traditional participants were less likely to adopt when the outgroup advocated adoption or when most of the community didn't adopt the intervention. Conclusions and implications: These results indicate conformity biases play a strong role in considerations about novel health interventions in indigenous communities, but also that traditional values are instrumental in shaping social learning biases. While previous focus has centered on market integration as a key predictor, we found the degree of traditionalism to be a critical and thus far underappreciated factor in mediating social learning.