Motivating Dramatic Interactions

Osterreichisches¨ Forschungsinstitut f ür/ Austrian Research Institute for / Artificial Intelligence TR–2005–02 Stefan Rank, Paolo Petta Motivating Dramatic Interactions • Freyung 6/6 • A-1010 Vienna • Austria • • Phone: +43-1-5336112 • • mailto:[email protected] • • http://www.ofai.at/ • Osterreichisches¨ Forschungsinstitut f ür/ Austrian Research Institute for / Artificial Intelligence TR–2005–02 Stefan Rank, Paolo Petta Motivating Dramatic Interactions The Austrian Research Institute for Artificial Intelligence is supported by the Federal Ministry of Education, Science and Culture. Citation: Rank S., Petta P. (2005): Motivating Dramatic Interactions. In Agents that Want and Like: Motivational and Emotional Roots of Cognition and Action, Proceedings of the AISB05 Symposium, April 12-15 2005, University of Hert- fordshire, Hatfield, UK, pp.102-107. Report: Rank S., Petta P.(2005): Motivating Dramatic Interactions. Technical Report, Osterreichisches¨ Forschungsin- stitut fur¨ Artificial Intelligence, Wien, TR-2005-02. Motivating Dramatic Interactions Stefan Rank? Paolo Petta?y ?Austrian Research Institute yDept. of Medical Cybernetics and Artificial Intelligence for Artificial Intelligence of the Centre for Brain Research Freyung 6/6, A-1010 Vienna, Austria at the Medical University of Vienna [email protected] Freyung 6/2, A-1010 Vienna, Austria [email protected] Abstract Simulated dramatic story-worlds need to be populated with situated software agents that act in a dramatically believable way. In order to provide flexible roleplayers, agent architectures should limit the required external macro-level control. We present work on an architecture that exploits social embedding and concepts from appraisal theories of emotion to achieve the enactment of simple cliche´ plots. The interplay of motivational constructs and the subjective evaluative inter- pretation of changes in an agent’s environment provide for the causal and emotional connections that can lead to the unfolding of a story. 1 Introduction software agents for the purpose of enacting dramatically interesting plots. These worlds present themselves to the single agent as inherently social This work is part of the ActAffAct project (Act- domains, as social interaction is often crucial for ing Affectively affecting Acting (Rank, 2004)) solving problems. In the ideal case the author of that researches a bottom-up approach to imitat- such a story-world would be able to shift from to- ing emotional characters that interact in a story- day’s specification of exact sequences of actions world. The goal is to achieve the unfolding of to the authoring of possible actions, regularities a plot-like structure while limiting the use of ex- in the environment, and the setting up of an initial ternal macro-level control—as exerted by, e.g., constellation of characters, including their general a director. The ideal level of external control traits. This would not necessarily be an easier pro- would be none at all, resulting in the emergence cess of creation but it could lead to a more flexi- of plot from the characters’ interaction, effec- ble, and possibly user-driven, experience of dra- tively turning the agents into reusable roleplay- matic structures. ers. The question that arises is what are the motivating elements in the control architecture of synthetic characters that can provide for a dramatically appropriate sequence of actions. Our approach views emotions—as described in appraisal theories (Frijda, 1986; Scherer et al., 2001; Ortony, 2003)—as the links between actions that render a plot plausible. Using an appraisal-based architecture that Emotions are the essence of a story (Elliott considers the social and physical lifeworld of an et al., 1998) and play a central role in engaging agent is seen as key to construct emotionally and drama. The conflicts between the characters in a dramatically believable characters for interactive play and the emotions involved in resolving them drama. This paper highlights aspects of our ex- are the constituents of a dramatic structure, a plot. tensions to a BDI architecture (belief, desire, in- Drama can be described as the art that deals with tention (Bratman et al., 1988; Huber, 1999)) that a refined version of emotional interaction between are pertinent to motivating dramatic actions in a individuals (Vogler, 1996; Egri, 1946). These minimal version of a cliche´ storyline. Situated ap- ideas provide a starting point and can serve as suc- praisal of all percepts, a three-phase model of be- cess criteria for the creation of dramatic story- haviours, and varied coping behaviours have been worlds, i.e., simulations that are inhabited by our first steps towards character-based narrative. 2 Enacting the Social Life- tions are suitable in which situation, and dis- world You are Embedded In play rules providing repertoires of how to express them). Interpretations of situations and developments Contrary to its physical surroundings, the intangi- in the social lifeworld are not a given: both within ble social lifeworld an agent is embedded in has an individual and in the society, they are the out- to be continually enacted and negotiated. We use come of negotiations and transactions, captured the term social lifeworld in the tradition of Agre e.g. in sociological models (Kemper, 1993) or and Horswill’s analytic endeavour (Agre and Hor- characterised in terms of personality traits. Pur- swill, 1997) to thicken the notion of environment. poseful functions such as threatening, sanction- Our focus on sociality combines the goal of reduc- ing, and amending, therefore are intrinsic be- ing the cognitive load for individual entities pop- havioural requirements, along with their affective ulating the environment with emphasising the rel- grounding in the social lifeworld. Emotional pro- evance of coordinative functions (Clancey, 1999) cesses (ranging from raw affect under rough and mediating between an individual and the (poten- undifferentiated circumstances, over fleets of feel- tial) current and future opportunities and threats ings in (yet) unclear scenarios, to fully articulated to satisfy an individual’s concerns (Frijda, 1986). “emotions” as result of detailed perception) medi- The notion of concern is defined as subjective ate the translation between the subjective worlds disposition to desire occurrence or nonoccurence of states, concerns and preferences, the abstract of a given kind of situation. This definition, taken enacted shared social lifeworld, and the status and from (Frijda, 1986), is related to but distinct from offerings of the physical world. goals and motives, as the latter terms induce con- The enactment of the social lifeworld is the notations of activity control. Concerns range from sphere of activity that is dominant in the con- very concrete considerations—i.e., relating to an text of dramatic interactions. The mechanisms of agent’s immediate tasks—to abstract ones—such emotional processes for interpreting and sustain- as feeling competent—that can lie dormant until ing this lifeworld and their influence on motiva- an emotionally pertinent event takes place. The tion form a fertile ground for drama. process of appraisal is described as a fast and possibly only partial evaluation of subjective signifi- cance of changes in the environment according to specific criteria. 3 Appraisal-based Architec- By operationalising these theoretical notions, ture we de-emphasise the role of high-level cognition (“thinking”) in routine functioning (Bargh and It is a big step from the qualitative appraisal Chartrand, 1999) and recognise the opportunity theories to an actual implementation. Several offered by available structures to constrain high- theoretical efforts investigate agent architectures level function within tractable bounds. Agre and that incorporate ideas about emotions (Isla et al., Horswill (1997) identify abstract locatedness and 2001; Frankel, 2002; Sloman and Scheutz, 2002; functionally significant relationships grounded in Gratch and Marsella, 2004; Marinier and Laird, the physical environment. Analogously, social 2004). The architecture we implemented uses lifeworld analysis considers the potential for in- ideas of TABASCO (Petta, 2003), the imple- ter-action with respect to loci of control at the mentation effort has been based on JAM, the Java macro level (e.g., power and status (Kemper, Agent Model (Huber, 2001). As a BDI archi- 1993)) as well as indirect access to (second and tecture, JAM provides a plan representation lan- higher level) resources (e.g., Aube,´ 1998). guage, goal- and event-driven (i.e., proactive and A situated agent’s dependence on regulari- reactive) behaviour, a hierarchical intention struc- ties thus extends beyond the physical world into ture, and utility-based action selection. socio-cultural constructs, whose maintenance can For our simple story-world we built a simula- e.g. be modelled as an interplay of conventions tion including a graphical representation of an en- (social norms) and evaluative processes (emo- vironment inhabited by four agents, taking on the tions) (Staller and Petta, 2001), with emotions roles of narrative archetypes: a hero, an antago- sustaining social norms, and culturally defined so- nist, a mentor, and a victim (Figure 1). To provoke cial norms in turn shaping and regulating emo- dramatic conflict, the agents are initialised with tions (e.g., with feeling rules defining which emo- conflicting top-level goals (as a first approxima- chitecture and their pertinence to appraisal

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