Recently, shared decision making (SDM) has come forward as a primary framework for decision making in healthcare. While current works on SDM are mostly grounded on normative and static decision models, this body of research has largely overlooked individuals' dynamic preferences, emotions and bounded cognitive capacities, which are instead compelling behavioral aspects of any decision space involving two or more individuals, like patients and physicians. In this paper, we address this gap by synthetizing and systematizing the current literature on SDM into key thematic domains. Building on this evidence, we advance a theoretical apparatus of SDM which integrates extant research with insights from the behavioral sciences. The resulting effort offers a behavioral model of SDM. It accounts for a social dimension in the construction of preferences as well as the constraints imposed by bounded rationality and their effects on patient-centered care. Overall, this work locates topical and practical insights as to how we might best understand interacting cognitive and emotional behavioral influences behind SDM.