Exploring by doing: How young chimpanzees discover surfaces through actions with objects

In human infants, perception-action routines that combine objects and surfaces in playful exploration presage using objects as tools. Banging a surface with a held object is a canonical example of this phenomenon. This longitudinal study revealed when and how exploratory activity with an object emerges in chimpanzees. We studied the development of exploratory actions with objects and surfaces in three infant chimpanzees between 13 and 21 months. The infants predominantly manipulated the cube or the surface separately at 13 and 15 months. By 21 months, all infants frequently combined the objects and surfaces, although they performed less differentiated actions with them than did an adult chimpanzee. Most of the infants' combinatorial actions were relatively gentle, involving placing and releasing rather than banging as seen in humans. Frequency of combination was affected with properties of surfaces rather than of objects.