Title: Coordinating Joint Action in a Real-Life Activity
Description: Humans engage in joint actions on a daily basis. Some of these joint actions are explicitly coordinated using, for example, speech and gesture, and the others are implicitly coordinated with the actions themselves. The first chapter of this dissertation reviews the use of speech, gesture, and intentional behavioral signals in explicit coordination of joint action and identifies three cognitive mechanisms that enable implicit coordination of joint action, namely, motor resonance, joint intentionality, and environmental and social affordance. The second chapter reports an empirical study exploring the employment of explicit and implicit coordination of joint action in a complex real-life joint activity, assembling a TV cart from its parts. We coded the content of the utterances and gestures that pairs of participants used throughout the assembly and the major and subordinate joint actions they performed. We then coded how each joint action was coordinated, that is, using speech, gestures, or action itself.

The results showed speech and gesture served primarily to establish and sustain a shared mental model of the environmental affordances between the co-actors, which occurred primarily at the beginning of the task and as the participants began to attach two major parts. For both major and subordinate joint actions alike, the specifics of the joint actions such as the goal and division of labor was primarily coordinated implicitly. We argue that the shared mental model scaffolded the participants’ implicit coordination of the actions. These findings provide evidence that action itself is a communicative device and part of the conversation between co-actors of a joint activity. They also lend support to the argument that joint action cannot be fully understood on the individual level but must be interpreted as a collective of which each individual is a part.