Emotional behavior trees

Often the AI techniques for decision making used in commercial games are predictable and unadaptive. Arguably, this causes a lack of realism for the players. We believe that emotions are a vital part in the creation of interesting and believable non-player characters for games. In this paper, we present an extension to behavior trees that incorporates emotions into the decision making. Specifically, we introduce a new type of priority selector whose priorities are dynamically evaluated to allow for emotional influence. This selector takes into account time-discounting, risk perception, and planning as relevant factors of the decision making that emotions greatly influence. The objective of our work is to provide game developers with a technique to model gaming scenarios using emotional behavior trees.