Human children, chimpanzees, and orangutans act rationally in an adaptive collaborative choice task.

Humans are believed to be uniquely motivated to form and pursue joint goals with conspecifics within collaborative activities. In experimental studies, a preference for collaboration emerges early in child development and is considered a cornerstone of sociocognitive development. Whether the human motivation to collaborate is an autapomorphic trait remains debated: Direct comparisons of collaborative motivations across primate species are rare and often fail to capture individuals' flexibility as well as variation in collaborative tendencies within and across species. The present study introduces an adaptive testing paradigm that allows for tailored comparisons of preferences for collaborative versus individual action by adjusting reward payoffs based on participants' prior choices. Human children aged 4-6 years from Leipzig, Germany (n = 64), zoo-housed chimpanzees (n = 3), and orangutans (n = 3) participated in the study. Participants of all three species predominantly acted as rational maximizers, favoring options yielding higher reward payoffs regardless of whether required actions involved joint or individual effort. Among human children, sensitivity to reward disparities increased with age. Chimpanzees' sensitivity to reward disparities was higher than that of orangutans. These findings demonstrate a greater flexibility in children's collaborative tendencies than previously assumed and suggest that, like nonhuman great apes, children may often act as rational maximizers in collaborative contexts. (PsycInfo Database Record (c) 2026 APA, all rights reserved).