Methods and systems monitor communications between users and analyze the communications to simultaneously determine, for a current time period, mental state variables of one of the users. Such mental state variables include the emotion of the user, the mood of the user, and the personality of the user. Additionally, such methods aggregate the emotion, the mood, and the personality using a hierarchical probabilistic graphical model that determines the highest probability path through a directed probabilistic graph to infer the mental state of the user. The directed probabilistic graph maintains a single state for the personality for the time period, and maintains multiple states for the emotion and the mood for the time period. These methods and systems output the mental state of the user.