Rychlowska et al. first looked at the relationship between the number of source countries (a measure of diversity) and a measure of 'overall expressivity' (a measure of the degree to which societal norms favour the open expression of emotion). They found that countries with more diverse origins had greater levels of expressivity.
Then things get interesting. Narrowing their analysis to nine countries (one of which was New Zealand), Rychlowska et al. identified two different clusters, or 'cultures of smiling'. In the first cluster, smiles were seen as being more about social bonding (e.g. smiles mean that a person “wants to be a close friend of yours”), while in the second cluster smiles were seen as more about hierarchy management (e.g. smiles mean that a person “feels superior to you”). The authors then looked at the prevalence of respondents from each country belonging to each cluster. Here's the key figure:
Notice that the U.S., New Zealand and Canada (all countries with very diverse patterns of past migration) have much higher proportions of Cluster 1 than the other countries. What does this mean? You could infer from these results that, in countries where people have to deal with a large amount of diversity, people use smiles to develop social bonds. In contrast, in countries that are more homogeneous, there is less need for smiles to be used for bonding and smiles instead are used in hierarchy management. Rychlowska et al. conclude that:
...findings reported here suggest that (i) 500 y of migration can create a culture of smiles and (ii) in such a culture, rules for nonverbal behavior are different from rules for nonverbal behavior in societies in which consensual emotional rules and expectations allow for predictability of emotional response and emotion regulation.With New Zealand becoming even more diverse over time, does this mean we will all be smiling more in the future? Or just interpreting those smiles differently?
[HT: The Atlantic, via Marginal Revolution]