The concepts of deliberation and deliberative democracy have attracted much attention in political theory over the past twenty years. At first seen as both highly idealised and unreflective of reality, they have now shed this accusation of impracticality, as practitioners and policy makers alike have attempted to institute deliberative principles on a national and international scale. Running alongside this has been the desire to both understand political deliberation and its effects more fully, and to then apply this new information back to deliberative democratic theory. This thesis sits in the latter tradition, presenting an empirical investigation of political deliberation and then discussing how it relates back to deliberative models of democracy. Where it departs from all of the contemporary experimental work, however, is the methodology and conceptual model it is founded upon. Embracing the decision and game theoretic approaches, I develop a three-fold framework to study the effects of deliberation on individual decision-making. After outlining two levels of ‘preference’ and ‘issue’, I focus on the third, which I term agency. I then compare a particular case of agency revision, which moves people from individualistic to team reasoning, before developing and putting into action an experimental test of the phenomenon. Finally, I then combine these results with the most recent drive in deliberative democracy towards a systemic approach, and derive an alternative, more positive argument for this recasting.