Before revision:  We present a new method for detecting social information in dominance hierarchies, that infers individual-level rules for aggression based on how aggression decisions are influenced by differences in social rank. We apply this method to 172 social groups across 85 species in 22 orders.
After revision:  We present a new method that can serve as a social assay to quantify how patterns of aggression depend upon information about the ranks of individuals within social dominance hierarchies. Applied to existing data on aggression in 172 social groups across 85 species in 22 orders.