Chapter 1 The Motivational Subsystem

• Sustainability: An agent must attend to its essential needs, such as hunger and thirst, and also know to avoid serious physical dangers, and so on (Toates 1986). • Purposefulness: The action of an agent must be chosen in accordance with some criteria, instead of completely randomly (Hull 1943, Anderson 1993), and those criteria are related to enhancing sustainability of an agent (Toates 1986). • Focus: An agent must be able to focus its activities with respect to specific purposes. That is, its actions need to be consistent, persistent, and contiguous, with respect to its purposes (Toates 1987). However, an agent needs to be able to give up some of its activities, temporally or permanently, when necessary (Simon 1967, Sloman 1986). • Adaptivity: An agent must be able to adapt its behavior (i.e., to learn) for the sake of improving its purposefulness, sustainability, and focus.