Representing Emotion and Mood States for Virtual Agents

2009

The development of intelligent virtual agents (IVAs) is a complex task featuring many sub problems. Concerning the education in this field, there is a good theoretical basis. However when it comes to the practical education – the platforms that can be used are scarce and mostly still not fully developed. Our goal is to create a platform, which would allow for a good practical education in the field of IVAs development. The first step towards this platform is a prototype implementation – project Emohawk – that will be described in this thesis. Project Emohawk features a partly emergent story and affect-driven architecture for IVAs control based on a psychologically plausible emotion model. Moreover a methodology was created analyzing this prototype implementation regarding the believability and emergent story potential.

2010

Characters in games and virtual worlds continue to gain improvements in both their visual appearance and more human-like behaviours with each successive generation of hardware. One area that seemingly would need to be addressed if this evolution in human-like characters is to continue is in the area of characters with emotions. To begin addressing this, the thesis focuses on answering the question "Can an emotional architecture be developed for characters in games and virtual worlds, that is built upon a foundation of formal psychology? Therefore a primary goal of the research was to both review and consolidate a range of background material based on the psychology of emotions to provide a cohesive foundation on which to base any subsequent work. Once this review was completed, a range of supplemental material was investigated including computational models of emotions, current implementations of emotions in games and virtual worlds, machine learning techniques suitable for implementing aspects of emotions in characters in virtual world, believability and the role of emotions, and finally a discussion of interactive characters in the form of chat bots and non-player characters. With these reviews completed, a synthesis of the research resulted in the defining of an emotion architecture for use with pre-existing agent behaviour systems, and a range of evaluation techniques applicable to agents with emotions. To support validation of the proposed architecture three case studies were conducted that involved applying the architecture to three very different software platforms featuring agents. The first was applying the architecture to combat bots in Quake 3, the second to a chat bot in the virtual world Second Life, and the third was to a web chat bot used for e-commerce, specifically dealing with question and answers about the companies services. The three case studies were supported with several small pilot evaluations that were intended to look at different aspects of the implemented architecture including; (1) Whether or not users noticed the emotional enhancements. Which in the two small pilot studies conducted, highlighted that the addition of emotions to characters seemed to affect the user experience when the encounter was more interactive such as in the Second Life implementation. Where the interaction occurred in a combat situation with enemies with short life spans, the user experience seemed to be greatly reduced. (2) An evaluation was conducted on how the combat effectiveness of combat bots was affected by the addition of emotions, and in this pilot study it was found that the combat effectiveness was not quite statistically reduced, even when the bots were running away when afraid, or attacking when angry even if close to death. In summary, an architecture grounded in formal psychology is presented that is suitable for interactive characters in games and virtual worlds, but not perhaps ideal for applications

… on Autonomous Agents, 2000

Abstract Several computational models of emotions have been proposed based on different approaches. Biologically inspired models developed generally for robots, consider a bottom-up approach whereas virtual agents are often based on a top-down approach. In this paper, we explore these two approaches. For the top-down approach, we analyze more particularly the problematic of virtual character's expression of emotions that should be in accordance with the social context.

Proceedings of the 7th International Conference on Telecommunications, 2003. ConTEL 2003., 2003

Research on networked applications that utilize multimodal information about their users' current emotional state are presently at the forefront of interest of the computer vision a n d artificial intelligence communities. Human faces may act as visual interfaces that help users feel at home when interacting with a computer because they are accepted as the most expressive means for communicating and recognizing emotions. Thus, a lifelike human face can enhance interactive applications by providing straightforward feedback to and from the users and stimulating emotional responses from them. Thus, virtual environments can employ believable, expressive characters since such features significantly enhance the atmosphere of a virtual world and Communicate messages far more vividly than any textual or speech information. In this paper, we present an abstract means of description of facial expressions, by utilizing concepts included in the MPEG-4 standard. Furthermore, we exploit these concepts to synthesize a wide variety of expressions using a reduced representation, suitable for networked and lightweight applications.

Computer Animation and …, 2008

Eludamos: Journal for Computer Game Culture, 2008

This paper attempts to highlight some of the research that has been conducted worldwide in the area of computational models of emotions, with a particular emphasis on agent emotions suitable for simulations and games. The intended outcome is to both review some of the more prominent research in the field, and to also ascertain the level of formal psychology that may underpin such work with a view to proposing that there is scope for an architecture built from the ground up, that arises from non-conflicting theories of emotion.

… Using Virtual Reality Technologies for Storytelling, 2005

This paper presents the mechanisms proposed by a generic cognitive architecture for virtual characters with emotional influenced behaviors, called cognitiva, to maintain behavior control at will without giving up the richness provided by emotions. This architecture, together with a progressive specification process for its application, have been used successfully to model 3D intelligent virtual actors for virtual storytelling.

2004

A new trend that has emerged in the field of applied artificial intelligence in the past few years is the incorporation of emotion emulation mechanisms in situated agent systems. Several researchers in the field of psychology and neural science agree that emotion is an essential aspect of human intelligence, diverging from the traditional treatment of emotion as something that inhibits rational thinking. This argument has also influenced the area of artificial intelligence and especially the young, yet vibrant field of Intelligent Virtual Agents, where it has become accepted that emotion is a key issue to achieve believable agent behaviour. The increased interest for emotions has resulted in several computational emotional models having been presented, with diverse approaches, generically classified into cognitive and non-cognitive, inspired by areas such as neural science. Hybrid approaches have also appeared, combining both cognitive and non-cognitive elements in an attempt to accurately describe the inner workings of emotional mechanisms. Such a hybrid model is the one we adopt in this paper, aiming to apply it to SimHuman, an intelligent virtual agent platform, in order to introduce emotion awareness and affective behaviour to the agent architecture.

2009

Abstract In this paper we proposed a computational model that automatically integrates a knowledge base with an affective model. The knowledge base presented as a semantic model, is used for an accurate definition of the emotional interaction of a virtual character and their environment. The affective model generates emotional states from the emotional output of the knowledge base. Visualization of emotional states is done through facial expressions automatically created using the MPEG-4 standard.