A Model for Temperament and Emotions on Robots Lyle N. Long Pennsylvania State University, 233 Hammond Building University Park, PA USA lnl@psu.edu Abstract. This paper describes a mathematical/computational model of emotions and temperaments (or personalities). This model has been implemented on cognitive mobile robots. Emotions such as fear, anger, sadness, happiness, disgust, surprise, and others can be modeled, and can vary due to reinforcers (e.g. rewards and punishments). The model incorporates exponential decay of the reinforcement effects, so without continual reinforcers the emotion will return to their steady-state values. It is shown that emotions and temperament are coupled through the theory. Most models of emotions do not relate emotions to temperament. The constants used in the model of emotions are related to the temperament of the robot. The main five temperaments discussed include Extrovert/ Introvert, Neurotic/Rational, Conscientious/Careless, Agreeable/Disagreeable, and Open/Reticent. The emotion and temperament model developed here has been incorporated into SS- RICS, which is a cognitive architecture developed at the Army Research Laboratory and tested in both mobile robots and in simulators. Keywords: Robotics · Emotions · Temperament · Affective 1 Introduction Emotions and temperament are crucial for animal survival (including human). Emotions allow rapid behavior adjustments to changing circumstances. Also, group survival is enhanced by having a mixture of temperaments. Temperament (or personality traits) and emotions are not the same thing. Temperaments are traits that an individual animal possesses that are innate and typically fixed for that animal’s life. Emotions vary continuously, sometimes on small time scales. In animals (including humans), temperament and emotion (and variations across groups) are as important to survival as cognition. They would make robots more effective also (LeDoux, 2000). Emotions and temperament would also be useful in human-robot interactions. There are five main types of temperament in humans and other animals, often called the Big Five (Digman, 1990): Extrovert vs. Introvert, Neurotic vs. Rational, Conscientious vs. Careless, Agreeable vs. Disagreeable, and Open vs. Reticent. These are explained in more detail in Table 1, which shows definitions of the terms used to describe the Big Five. The first definition is from the Oxford dictionary (www.oxforddictionaries.com) and the second is from the Merriam-Webster dictionary (www.merriam-webster.com).