The Design of Charismatic Behaviors for Virtual Humans

Lecture Notes in Computer Science, 2015

Developing believable virtual characters has been a subject of research in many fields including graphics, animations, artificial intelligence, and humancomputer interaction. One challenge towards commoditizing the use of virtual humans is the ability to algorithmically construct characters of different stereotypes. In this paper, we present our efforts in designing virtual characters that can exhibit non-verbal behaviors to reflect varying degrees of warmth and competence, two personality traits shown to underlie social judgments and form stereotypical perception. To embark on developing a computational behavior model that portrays these traits, we adopt an iterative design methodology tuning the design using theory from theatre, animation and psychology, expert reviews, user testing and feedback. Using this process we were able to construct a set of virtual characters that portray variations of warmth and competence through combination of gestures, use of space, and gaze behaviors. In this paper we discuss the design methodology, the resultant system, and initial experiment results showing the promise of the model.

2002

In this paper, we present an integrated method of linking personality and emotion with the response generation and expression synthesis of Virtual Humans. The characters are powered by a dialogue system that consists of a large set of basic interactions between user and computer. These interactions are encoded in finite state machines. Transitions are linked with conditions and actions that can be connected with external modules. One of these modules is a personality module. In this way, responses of the virtual human depend not only on input given by a user, but also on its personality and emotional state. The dialogue system is connected to a 3D face that performs the speech and facial animation, together with facial expressions that reflect the personality specification.

Frontiers in Virtual Reality, 2023

Practicing public speaking to simulated audiences created in virtual reality environments is reported to be effective for reducing public speaking anxiety. However, little is known about whether this effect can be enhanced by encouraging the use of gestures during VR-assisted public speaking training. In the present study two groups of secondary schools underwent a three-session public speaking training program in which they delivered short speeches to VRsimulated audiences. One group was encouraged to "embody" their speeches through gesture while the other was given no instructions regarding the use of gesture. Before and after the training sessions participants underwent respectively a pre-and a post-training session, which consisted of delivering a similar short speech to a small live audience. At pre-and post-training sessions, participants' levels of anxiety were self-assessed, their speech performances were rated for persuasiveness and charisma by independent raters, and their verbal output was analyzed for prosodic features and gesture rate. Results showed that both groups significantly reduced their self-assessed anxiety between the pre-and posttraining sessions. Persuasiveness and charisma ratings increased for both groups, but to a significantly greater extent in the gesture-using group. However, the prosodic and gestural features analyzed showed no significant differences across groups or from pre-to post-training speeches. Thus, our results seem to indicate that encouraging the use of gesture in VRassisted public speaking practice can help students be more charismatic and their delivery more persuasive before presenting in front of a live audience.

Autonomous Agents and Multi-Agent Systems

Designers of virtual agents have a combinatorically large space of choices for the look and behavior of their characters. We conducted two between-subjects studies to explore the systematic manipulation of animation quality, speech quality, rendering style, and simulated empathy, and its impact on perceptions of virtual agents in terms of naturalness, engagement, trust, credibility, and persuasion within a health counseling domain. In the first study, animation was varied between manually created, procedural, or no animations; voice quality was varied between recorded audio and synthetic speech; and rendering style was varied between realistic and toon-shaded. In the second study, simulated empathy of the agent was varied between no empathy, verbalonly empathic responses, and full empathy involving verbal, facial, and immediacy feedback. Results show that natural animations and recorded voice are more appropriate for the agent's general acceptance, trust, credibility, and appropriateness for the task. However, for a brief health counseling task, animation might actually be distracting from the persuasive message, with the highest levels of persuasion found when the amount of agent animation is minimized. Further, consistent and high levels of empathy improve agent perception but may interfere with forming a trusting bond with the agent.

2012

Convincing conversational agents require a coherent set of behavioural responses that can be interpreted by a human observer as indicative of a personality. This paper discusses the continued development and subsequent evaluation of virtual agents based on sound psychological principles. We use Eysenck's theoretical basis to explain aspects of the characterization of our agents, and we describe an architecture where personality affects the agent's global behaviour quality as well as their backchannel productions. Drawing on psychological research, we evaluate perception of our agents' personalities and credibility by human viewers (N=187). Our results suggest that we succeeded in validating theoretically grounded indicators of personality in our virtual agents, and that it is feasible to place our characters on Eysenck's scales. A key finding is that the presence of behavioural characteristics reinforces the prescribed personality profiles that are already emerging from the still images. Our long-term goal is to enhance agents' ability to sustain realistic interaction with human users, and we discuss how this preliminary work may be further developed to include more systematic variation of Eysenck's personality scales.

Scientia, 2002

Abstract. This article presents the work carried out for a Master thesis and its main contributions. The thesis focuses on facial animation, more specifically on facial animations with synchronization between speech and facial expressions. First, the motivation behind this ...

2005

Virtual agents are used to interact with humans in a myriad of applications. However, the agents often lack the believability necessary to maximize their effectiveness. These agents, or characters, lack personality and emotions, and therefore the capacity to emotionally connect and interact with the human. This deficiency prevents the viewer from identifying with the characters on a personal level. This research explores the possibility of automating the expression of a character's mental state through its body language.

Safety & Fire Technology, 2024

Purpose: This article aims to explore and advance the field of public speaking training through the use of virtual reality (VR) and virtual avatars. The focus is on addressing the challenges faced in traditional public speaking training methods by leveraging the capabilities of VR technology. Project and methods: The project involved developing an innovative algorithm designed to control the behaviour of virtual avatars during public speaking training in a VR environment. This algorithm integrates multiple aspects of human communication, including posture modelling, voice modulation, greetings mannerisms, eye contact management, gestural communication and interactive responsiveness. The methodology combined theoretical research and practical implementation, involving a comprehensive review of existing solutions and the development of a sophisticated, integrated algorithm. The project utilised advanced programming techniques and the latest VR technology, tested in simulated public speaking scenarios. Results: The results of implementing this algorithm in VR-based training applications showed a significant improvement in the authenticity and effectiveness of public speaking training. The virtual avatars, powered by the algorithm, were able to simulate realistic human behaviours and responses, thus providing a more engaging and immersive learning experience for users. The application offered a variety of realistic training scenarios, interactive avatar feedback, customisation options, and progress tracking and analysis features. The study found that the algorithm successfully enhanced participants' public speaking skills, reducing anxiety and improving their overall communication abilities. Conclusions: The research conducted in an "e-Zawody" project concludes that the integration of VR and virtual avatars significantly enhances public speaking training, offering a novel, effective and engaging approach. The development of the algorithm marks a pivotal advancement in educational technology, providing a platform that surpasses traditional training methods. However, the study acknowledges technological limitations and the need for ongoing research and development. Future efforts should focus on enhancing the realism and interactivity of virtual avatars and expanding the application of VR-based training across various fields. The findings suggest a promising direction for the future of public speaking training, with VR technology poised to play a crucial role in the evolution of educational methodologies.

2003

In this paper, we present our approach to modelling perceptive 3D virtual characters with emotion and personality. The characters are powered by a dialogue system that consists of a large set of basic interactions between the user and the computer. These interactions are encoded in finite state machines. The system is integrated with an expression recognition system, that tracks a user's face in real-time and obtains expression data. Also, the system includes a personality and emotion simulator, so that the character responds naturally to both the speech and the facial expressions of the user. The virtual character is represented by a 3D face that performs the speech and facial animation in real-time, together with the appropriate facial expressions.

IEEE …, 2011

Convincing conversational agents require a coherent set of behavioural responses that can be interpreted by a human observer as indicative of a personality. This paper discusses the continued development and subsequent evaluation of virtual agents based on sound psychological principles. We use Eysenck's theoretical basis to explain aspects of the characterization of our agents, and we describe an architecture where personality affects the agent's global behaviour quality as well as their backchannel productions. Drawing on psychological research, we evaluate perception of our agents' personalities and credibility by human viewers (N=187). Our results suggest that we succeeded in validating theoretically grounded indicators of personality in our virtual agents,and that it is feasible to place our characters on Eysenck's scales. A key finding is that the presence of behavioural characteristics reinforces the prescribed personality profiles that are already emerging from the still images. Our long-term goal is to enhance agents' ability to sustain realistic interaction with human users, and we discuss how this preliminary work may be further developed to include more systematic variation of Eysenck's personality scales.