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

Imitation research has been hindered by (1) overly molecular analyses of be haviour that ignore hierarchical structure, and (2) attempts to disqualify observational evidence. Program-level imitation is one of a range of cognit ive skills for scheduling efficient novel behaviour, in particular enabling an individual to purloin the organization of another's behaviour for its o wn. To do so, the individual must perceive the underlying hierarchical sche dule of the fluid action it observes and must understand the local function s of subroutines within the overall goal-directed process. Action-level imi tation, 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 a bilities underlying program-level imitation that make it possible for the u nderlying structure of complex actions to be dissected visually and recreat ed in behaviour.