You're so right, actually there is nothing new in this idea. Kalman filters (so basically belief propagation based on gaussian observations) were already used by DL Kleinman in 1970 to model aircraft pilots behavior. We are way past this simplistic hypothesis. Actually, quantum dynamics (yeah why not, it's just a model) seem to better describe human decision making than classical stochastic models (Quantum dynamics of human decision-making - http://www.sciencedirect.com/science/article/pii/S0022249606...)