Preparatory responses to socially determined, mutually exclusive possibilities in chimpanzees and children.

The capacity to imagine and prepare for alternative future possibilities is central to human cognition. Recent research suggests that between age 2 and 4 children gradually begin to demonstrate a capacity to prepare for two simple, mutually exclusive alternatives of an immediate future event. When children were given the opportunity to catch a target an experimenter dropped into an inverted Y-shaped tube, 2-year olds-as well as great apes-tended to cover only one of the exits, whereas 4-year-olds spontaneously and consistently prepared for both possible outcomes. Here we gave children, age 2 to 4 years, and chimpanzees a different opportunity to demonstrate potential competence. Given that social behaviour is particularly full of uncertainty, we developed a version of the task where the outcome was still unpredictable yet obviously controlled by an experimenter. Participants could ensure they would catch the target by simply covering two tube exits. While 4-year-olds demonstrated competence, chimpanzees and the younger children instead tended to cover only one exit. These results substantiate the conclusion that the capacity for simultaneous preparation for mutually exclusive event outcomes develops relatively late in children and they are also in line with the possibility that our close animal relatives lack this capacity.