Cooperative and competitive interactions modulate expectations about resource distribution in 13-month-old infants

Cooperation and resource distribution are central properties of human sociality. The long-term stability of cooperative ventures depends on linking obtained benefits to the efforts invested by collaborating partners. Previous studies demonstrated that infants start to both understand and engage in cooperative activities early on and show early sensitivity to how resources are distributed among social partners. It remains unknown, however, whether infants' intuitions about expectable resource sharing are influenced by the cooperative or competitive nature of the social partners' preceding interactions. We examined this issue by presenting 192 thirteen-month-old infants with various “predator-prey” chasing events in which two goal-directed agents interacted either cooperatively or competitively to capture a chasee. Using a violation-of-expectation looking-time paradigm we tested infants' expectations about different patterns of resource distribution (involving sharing vs. monopolizing) the agents engaged in after capturing the prey. Following familiarization to Cooperative Chasing interactions infants looked significantly longer when the obtained goal outcome was consumed by one of the chasers alone than when it was shared. In contrast, after observing Competitive Chasing events infants showed the opposite pattern of expectations looking longer when the captured prey was shared by the two chasers than when one of them consumed it on its own. Together with the control conditions, these findings suggest that 13-month-olds use the cooperative versus competitive structure of a preceding interaction to generate expectations regarding the sharing or monopolization of the obtained resource.