Better Together: 14-Month-Old Infants Expect Agents to Cooperate.

Humans engage in cooperative activities from early on and the breadth of human cooperation is unparalleled. Human preference for cooperation might reflect cognitive and motivational mechanisms that drive engagement in cooperative activities. Here we investigate early indices of humans' cooperative abilities and test whether 14-month-old infants expect agents to prefer cooperative over individual goal achievement. Three groups of infants saw videos of agents facing a choice between two actions that led to identical rewards but differed in the individual costs. Our results show that, in line with prior research, infants expect agents to make instrumentally rational choices and prefer the less costly of two individual action alternatives. In contrast, when one of the action alternatives is cooperative, infants expect agents to choose cooperation over individual action, even though the cooperative action demands more effort from each agent to achieve the same outcome. Finally, we do not find evidence that infants expect agents to choose the less costly alternative when both options entail cooperative action. Combined, these results indicate an ontogenetically early expectation of cooperation, and raise interesting implications and questions regarding the nature of infants' representations of cooperative actions and their utility.