Ease and control: the cognitive benefits of hierarchy

Human and animal dominance hierarchies show a pyramidal structure guiding adult and infant social inferences

This study investigates the structure of social hierarchies. We hypothesized that if social dominance relations serve to regulate conflicts over resources, then hierarchies should converge towards pyramidal shapes. Structural analyses and simulations confirmed this hypothesis, revealing a triadic-pyramidal motif across human and non-human hierarchies (114 species). Phylogenetic analyses showed that this pyramidal motif is widespread, with little influence of group size or phylogeny. Furthermore, nine experiments conducted in France found that human adults (N = 120) and infants (N = 120) draw inferences about dominance relations that are consistent with hierarchies' pyramidal motif. By contrast, human participants do not draw equivalent inferences based on a tree-shaped pattern with a similar complexity to pyramids. In short, social hierarchies exhibit a pyramidal motif across a wide range of species and environments. From infancy, humans exploit this regularity to draw systematic inferences about unobserved dominance relations, using processes akin to formal reasoning.

Memory bias for social hierarchical information is modulated by perceived social rank

Hierarchies pervade human society, characterising its members along diverse dimensions ranging from their abilities or skills in a particular domain to their economic status or physical stature. One intriguing aspect of the centrality of hierarchies, relative to egalitarian constructs, is that hierarchically-organised social information appears to be remembered more easily than non-hierarchically-organised information. However, it is not yet clear how one's social rank within a hierarchy influences processing. In a pre-registered study with 66 healthy participants, we examined memory recall for hierarchical information when participants themselves were positioned higher in the hierarchy versus lower in the hierarchy, both relative to an egalitarian control condition. The results replicate previous work showing that hierarchical information is memorised faster relative to the egalitarian control. Importantly, this effect was modulated by the participant's position within the hierarchy, with higher positioned participants memorising information faster than lower-positioned participants. This study provides new evidence showing biases in memory will favour hierarchical information if modulated by perceptions of one's own social rank.