In this article, we bring together recent findings from developmental science and cognitive neuroscience to argue that perception-action coupling constitutes the fundamental mechanism of motor cognition. A variety of empirical evidence suggests that observed and executed actions are coded in a common cognitive and neural framework, enabling individuals to construct shared representations of self and other actions. We review work to suggest that such shared representations support action anticipation, organization, and imitation. These processes, along with additional computational mechanisms for determining a sense of agency and behavioral regulation, form the fabric of social interaction. In addition, humans possess the capacity to move beyond these basic aspects of action analysis to interpret behavior at a deeper level, an ability that may be outside the scope of the mirror system. Understanding the nature of shared representations from the vantage point of developmental and cognitive science and neuroscience has the potential to inform a range of motor and social processes. This perspective also elucidates intriguing new directions and research questions and generates specific hypotheses regarding the impact of early disorders (e.g., developmental movement disorders) on subsequent action processing.
1. A Meeting of Minds: Integrating Developmental Science and Cognitive Neuroscience in the Domain of Motor Cognition
In the past decade, exciting new discoveries in developmental science and cognitive neuroscience have been made in domains such as action perception, theory of mind, and affective processing. Historically, research in these domains has proceeded along parallel paths, often addressing similar research topics and areas of inquiry. However, to date, communication between the two academic fields has been rare and limited (but see Decety & Jackson, 2004; Decety & Sommerville, 2003; and Saxe, Carey, & Kanwisher, 2004, for exceptions). Our intention in this article is to articulate new developmental data with cognitive neuroscience findings in the domain of motor cognition.
From our perspective, motor cognition refers to the way in which we think about and conceive of our own and others' actions. We argue that much of how we think about others' actions, and in turn engage in social interaction, arises from the activation or simulation of our own motor representations (see Jeannerod, 2001). Thus, we consider motor cognition to encompass all the processes involved in the planning, preparation, and production of our own actions, as well as the processes involved in anticipating, predicting, and understanding the actions of others. We assume that processes operate primarily at the covert, automatic level and, as such, without our conscious awareness.
Our perspective in this article is consistent with recent theories of embodied cognition, an emerging theme in both cognitive science (Barsalou, 1999, 2003; Barsalou, Simmons, Barbey, & C. D. Wilson, 2003; Pecher, Zeelenberg, & Barsalou, 2004) and developmental science (e.g., E. Thelen, 1995; E. Thelen, Schoner, Scheier, & Smith, 2001). Traditional theories of cognition assume that knowledge consists of amodal redescriptions of sensory, motor, and introspective states (including emotions, affects, appetitive states, cognitive operations, and beliefs; see Barsalou, 1999) that originally accompanied an event or experience. According to these theories, knowledge exists independently of these states and operates according to different principles. In contrast, embodied theories of cognition construe knowledge as partial simulations of these sensory, motor, and introspective states (e.g., Barsalou, 2003; Barsalou, Niedenthal, Barbey, & Ruppert, 2003). One intuitive example is that empathy, or understanding another person's emotional state, comes from mentally "recreating" this person's feelings in us (Decety & Jackson, 2004; Preston & de Waal, 2002). …