According to an influential theory in cultural evolution, within-group similarity of culture is explained by a human ‘conformist-bias’, which is a hypothesized evolved predisposition to preferentially follow a member of the majority when acquiring ideas and behaviours. However, this notion has little support from social psychological research. In fact, a major theory in social psychology (Latané and Wolf (1981) argues for what is in effect a ‘nonconformist-bias’: by analogy to standard psychophysics they predict minority sources of influence to have relatively greater impact than majority sources. Here we present a new mathematical model and an experiment on social influence, both specifically designed to test these competing predictions. The results are in line with nonconformism. Finally, we discuss within-group similarity and suggest that it is not a general phenomenon but must be studied trait by trait.
Existing mathematical models suggest that gene-culture coevolution favours a conformist bias in social learning, that is, a psychological mechanism to preferentially acquire the most common cultural variants. Here we show that this conclusion relies on specific assumptions that seem unrealistic, such as that all cultural variants are known to every individual. We present two models that remove these assumptions, showing that: 1) the rate of cultural evolution and the adaptive value of culture are higher in a population in which individuals pick cultural variants at random (Random strategy) rather than picking the most common one (Conform strategy); 2) in genetic evolution the Random strategy out-competes the Conform strategy, unless cultural evolution is very slow, in which case Conform and Random usually coexist; 3) the individuals’ ability to evaluate cultural variants is a more important determinant of the adaptive value of culture than frequency-based choice strategies. We also review existing empirical literature and game-theoretic arguments for conformity, finding neither strong empirical evidence nor a strong theoretical expectation for a general conformist bias. Our own vignette study of social learning shows that people may indeed use different social learning strategies depending on context.
The thermal stability of heat-stabilised polyamide 66 in an oxidative environment is evaluated by DSC. The oxidative stability
of the polyamide decreases as a result of repeated injection moulding. The results also indicate that the presence of glass
fibres in the polyamide has a negative influence on the oxidative stability. Both isothermal and dynamic DSC measurements
seem to be useful tools for assessing the stability of polyamides and there is a relationship between data determined using