Do infants expect physically competent agents to gain access to contested resources?

Social hierarchy is important for both individuals and groups, but when and how the human mind begins to establish it remains less well understood. Past studies have demonstrated that even infants tend to expect agents with certain characteristics (e.g., a larger body size) to prevail in dyadic zero-sum conflicts. Building on literature suggesting that adults and children associate high status with competent rather than incompetent individuals, we conducted three preregistered experiments to test whether infants predict that a physically competent agent will prevail in conflicts with a physically incompetent agent. In Experiment 1, 14- to 15-month-old infants watched a "competent" agent who jumped over a barrier and moved across a stage, and an "incompetent" agent who failed to jump over the barrier and, as a result, could not move across the stage. Infants looked longer, indicating a violation of expectation, when the incompetent agent subsequently prevailed in obtaining an object compared to when the reverse outcome was presented. Infants' responses in Experiments 2a and 2b, although not significantly different from those in Experiment 1, suggested that this expectation was not merely due to differences in the agents' goal achievement outcomes or the heights they could jump over the barriers. These findings suggest that infants expect physically competent agents-those who can achieve goals through physical abilities-to prevail in conflicts with agents who lack such demonstrations. This implies that the psychological bias to attribute high social rank to competent individuals is rooted in early development.