Papers

Facial animation has reached a high level of photorealism. Skin is rendered with grain and translucency, wrinkles are accurate and dynamic. These recent visual improvements are not fully tested for their contribution to the perceived expressiveness of virtual characters. This paper presents a perceptual study assessing the impact of different rendering modes of expressive wrinkles on users' perception of facial expressions of basic and complex emotions. Our results suggest that realistic wrinkles increase agent's expressivity... Read more

Wrinkles, blushing, sweating and tears are physiological manifestations of emotions in humans. Therefore, the simulation of these phenomena is important for the goal of building believable virtual humans which interact naturally and effectively with humans. This paper describes a real-time model for the simulation of wrinkles, blushing, sweating and tears. A study is also conducted to assess the influence of the model on the perception of surprise, sadness, anger, shame, pride and fear. The study... Read more

This paper presents a quest for the most suitable setting and method to assess the naturalness of the output of an existing algorithm for the generation of multimodal referring expressions. For the evaluation of this algorithm a setting in Second Life was built. This paper reports on a pilot study that aimed to assess (1) the suitability of the setting and (2) the design of our evaluation method. Results show that subjects are able to... Read more

This paper presents the results of a field study of the COHIBIT museum exhibit. Its purpose is to convey knowledge about car-technology and virtual characters in an entertaining way. Two life-sized virtual characters interact with the visitors and support them in constructing car models with specific tangible car modules. The evaluation should reveal what makes the exhibit successful in terms of an overall user impression and how users rate the employed virtual characters. The focus... Read more

This paper presents two attempts in integrating attentiveness into a virtual quiz agent in the situation when multiple game participants present. One of them features an utterance strategy to determine when and whom to talk to among the participants. The other one features a SVM (support vector machine) triggered transition state model of the agent's attitude toward the participants in expressing observable behaviors. Both of them are driven by timings determined on video and audio... Read more

In human-computer interaction social behavior towards computers like flattery, reciprocity, and politeness have been observed. In order to determine whether the results can be replicated when interacting with embodied conversational agents (ECA), we conducted an experimental study. 63 participants evaluated the ECA Max after a 10-minute conversation. The interview situation was manipulated in three conditions: Being questioned by Max himself, being questioned by paper-and-pencil questionnaire in the same room facing Max, and being questioned by... Read more

In this paper, we present a study to evaluate the impact of adaptive feedback on the effectiveness of a pedagogical agent for an educational computer game. We compare a version of the game with no agent, and two versions with agents that differ only in the accuracy of the student model used to guide the agent's interventions. We found no difference in student learning across the three conditions, and we report an analysis to understand... Read more

Virtual training systems provide an effective means to train people for complex, dynamic tasks such as crisis management or firefighting. Intelligent agents are often used to play the characters with whom a trainee interacts. To increase the trainee's understanding of played scenarios, several accounts of agents that can explain the reasons for their actions have been proposed. This paper describes an empirical study of what instructors consider useful agent explanations for trainees. It was found... Read more

Avatars are frequently used in virtual worlds and online games to convey emotions across cultures. However, our previous study suggested there are cultural differences in recognizing avatar's facial expressions [1]. Yuki et al.'s study using emoticons and photorealistic human face images suggests Americans tend to interpret emotions based on the mouth, while Japanese tend to focus on the eyes [2]. Inspired by Yuki's study, this study uses cartoonish avatar faces to find cultural differences in... Read more

Coming to open domain dialog it is still unrealistic to implement needed knowledge resources and dialog skills linguistically. Since the Non Player Characters (NPC) in our NPC Engine should be capable of open conversation we decided to use an Artificial Intelligence Markup Language (AIML) [1] chatbot as a first workaround. However AIML chatbots are not linguistically motivated, they use surface structures in tradition of Weizenbaums ELIZA [2], wherefore they do have too many shortcomings to... Read more