Embodied Conversational Agents (ECAs) are a new type of computer interface which have human-like bodies and conversational skills. Users interacting with agents will be more engaged and participative if the agents exhibit behaviors which look coherent across different situations and emotional states. In the present work, we aim at increasing agents' believability by looking at two main aspects of the problem: - an agent must be able to show its emotional state and communicative intentions not only through specific facial expressions, gestures, etc., but also by varying the quality of its movements (e.g., their speed, amplitude, etc.) and the choice of the modalities that are used to communicate; - the agent must maintain a distinctive behavior, that is, its global behavior tendency has to remain apparent during any communication. We have developed a model to solve the two above issues. We have evaluated the realism and believability of the resulting agent's behaviors through perceptual tests and application scenario. The resulting system is highly extensible and configurable. It can also be used as a research tool to study human communication.

During a conversation, listeners do not assimilate passively all of the speaker's words; they actively participate in the interaction providing information about how they feel and what they think of the speaker's speech. The speaker relies on signals emitted by the listener to know if he is listening or not, understanding or not, agreeing or not, etc. This informs the speaker on the success or failure of the communication and helps him to decide how to carry on with the interaction. In this thesis, to refer to signals provided by listeners, we adopt the term backchannel proposed by Yngve. We define backchannels as acoustic and non-verbal signals provided during the speaker's turn to exchange information about the communicative functions: contact, perception, understanding, and attitude. Backchannels are emitted in a non-intrusive way: that is, without interrupting the speaker's speech. Two fundamental characteristics of backchannels are: (i) they can be emitted at different level of intentionality; (ii) they can be reactive (deriving from a first process of perception of the speaker's speech) or response (deriving from a more aware evaluation). A particular form of backchannel is the mimicry of the speaker's behavior. By mimicry, we mean the behavior displayed by an individual who does what another person does. This type of behavior has been proven to play quite an important role during conversations. Due to the importance of the listener's behavior, in this thesis we propose to implement a model that generates this type of behavior for an Embodied Conversational Agent while interacting with a user. We aim to improve the human-machine interaction.

This book constitutes revised selected papers from the 23rd Argentina Congress on Computer Science, CACIC 2017, held in La Plata, Argentina, in October 2017. The 28 papers presented in this volume were carefully reviewed and selected from a total of 132 submissions. They were organized in topical sections named: intelligent agents and systems; distributed and parallel processing; computer technology applied education; graphic computation, images and visualization; software engineering; databases and data mining; hardware architectures, networks and operating systems; innovation in software systems; signal processing and real-time systems; computer security; and innovation in computer science education.

Computer graphics is now used in various fields; for industrial, educational, medical and entertainment purposes. The aim of computer graphics is to visualize real objects and imaginary or other abstract items. In order to visualize various things, many technologies are necessary and they are mainly divided into two types in computer graphics: modeling and rendering technologies. This book covers the most advanced technologies for both types. It also includes some visualization techniques and applications for motion blur, virtual agents and historical textiles. This book provides useful insights for researchers in computer graphics.

Communication is not just about the transfer of verbal information. Gestures, facial expressions, intonation and body language are all major sources of information during conversation. This book presents a new perspective on communication, one that will help us to better understand humans, and also to build machines that can communicate.

This book constitutes the proceedings of the 13th International Conference on Intelligent Virtual Agents, IVA 2013, held in Edinburgh, UK, in August 2013. There was a total of 94 submissions. The 18 full and 18 short papers presented in this volume were carefully reviewed and selected for inclusion in the book. In addition, the volume lists the 34 posters which were on display during the conference. The papers are organized in topical sections named: cognitive models; applications; dialogue, language, speech; non-verbal behaviour; and social, cultural models and agents.

This book constitutes the thoroughly refereed post-proceedings of the 7th International Workshop on Gesture-Based Human-Computer Interaction and Simulation, GW 2007, held in Lisbon, Portugal, in May 2007. The 31 revised papers presented were carefully selected from 53 submissions. The papers are organized in topical sections on analysis and synthesis of gesture; theoretical aspects of gestural communication and interaction; vision-based gesture recognition; sign language processing; gesturing with tangible interfaces and in virtual and augmented reality; gesture for music and performing arts; gesture for therapy and rehabilitation; and gesture in Mobile computing and usability studies.

The International Conference on Computational Science (ICCS 2004) held in Krak ́ ow, Poland, June 6–9, 2004, was a follow-up to the highly successful ICCS 2003 held at two locations, in Melbourne, Australia and St. Petersburg, Russia; ICCS 2002 in Amsterdam, The Netherlands; and ICCS 2001 in San Francisco, USA. As computational science is still evolving in its quest for subjects of inves- gation and e?cient methods, ICCS 2004 was devised as a forum for scientists from mathematics and computer science, as the basic computing disciplines and application areas, interested in advanced computational methods for physics, chemistry, life sciences, engineering, arts and humanities, as well as computer system vendors and software developers. The main objective of this conference was to discuss problems and solutions in all areas, to identify new issues, to shape future directions of research, and to help users apply various advanced computational techniques. The event harvested recent developments in com- tationalgridsandnextgenerationcomputingsystems,tools,advancednumerical methods, data-driven systems, and novel application ?elds, such as complex - stems, ?nance, econo-physics and population evolution.

This book constitutes the refereed proceedings of the 6th International Workshop on Intelligent Virtual Agents, IVA 2006. The book presents 24 revised full papers and 11 revised short papers together with 3 invited talks and the abstracts of 19 poster papers. The papers are organized in topical sections on social impact of IVAs, IVAs recognizing human behavior, human interpretation of IVA behavior, embodied conversational agents, characteristics of nonverbal behavior and more.

Recent years have seen the rise of a remarkable partnership between the social and computational sciences on the phenomena of emotions. This book reports on the state-of-the-art in both social science theory and computational methods, and illustrates how these two fields, together, can both facilitate practical computer/robotic applications and illuminate human social processes.