Common ground on which to approach the origins of higher cognition - Response

Imitation research has been hindered by (1) overly molecular analyses of behaviour that ignore hierarchical structure, and (2) attempts to disqualify observational evidence. Program-level imitation is one of a range of cognitive skills for scheduling efficient novel behaviour, in particular enabling an individual to purloin the organization of another's behaviour for its own. To do so, the individual must perceive the underlying hierarchical schedule of the fluid action it observes and must understand the local functions of subroutines within the overall goal-directed process. Action-level imitation, copying strings of actions linearly without any such understanding, is less valuable for acquiring complex behaviour and may often have other, social functions. At present, we lack a mechanistic understanding of the abilities underlying program-level imitation that make it possible for the underlying structure of complex actions to be dissected visually and recreated in behaviour.