Game theory has been useful for understanding risk-taking and cooperative behavior. In the present study, subjects played the Hawk-Dove game with simulated and embodied (robotic) neural agents which used a neurobiologically plausible model of action selection and adaptive behaviors. Subjects had their serotonin levels temporarily altered through acute tryptophan depletion (ATD). The traditional assumption for subject data from Game-theory-ATD or human robot interaction (HRI) studies is that all participants come from the same underlying distribution or same group. We used probabilistic graphical models in order to determine potential sub-group affiliations based on the subjects’ responses while playing the Hawk-Dove game. The results from the models indicate sub-groups within a subject population exist. We find that two-group, one that tends toward cooperation and the other that tends toward aggression, best describes the effect of subject behavior in response to ATD and embodiment.