Embodied Conversational Agents (i.e., avatars; ECAs) are appearing in increasingly many everyday contexts, such as e-commerce, occupational training, and airport security. Also common to a typical person's daily life is persuasion. Whether being persuaded or persuading, the ability to change another person's attitude or behavior is a thoroughly researched topic. However, little is known about ECAs' ability to persuade and whether basic persuasion principles from human-human interactions will hold in human-ECA interactions. This work investigates this question. First, a broad review of persuasion literature, which serves as an inventory of manipulations to test in ECA contexts, is presented. This literature review serves an inventory to guide future Persuasive ECA work. The ECA literature is then reviewed. Two preliminary studies exploring the effects of physical attractiveness, voice quality, argument quality, common ground, authority, and facial similarity are presented. Finally, the culminating study testing the effectiveness of ECAs to elicit self-disclosure in automated interviewing is presented and discussed. The findings of that automated interviewing study suggest that ECAs may replace humans in automated interviewing contexts. The findings also suggest that ECAs that are manipulated to look like their interviewees are able to induce greater likeability, establish more rapport, and elicited more self-referencing language than ECAs that do not look like the interviewees.

Les Agents Conversationnels Animés sont des personnages virtuels dont la fonction principale est d'interagir avec l'utilisateur. Ils sont utilisés dans différents domaines tels que l'assistance personnelle, l'entrainement social ou les jeux vidéo et afin d'améliorer leur potentiel, il est possible de leur donner la capacité d'exprimer des comportements similaires à ceux des humains. Les utilisateurs, conscient d'interagir avec une machine, sont tout de même capable d'analyser et d'identifier des comportements sociaux à travers les signaux émis par les agents. La recherche en ACA s'est longtemps intéressée aux mécanismes de reproduction et de reconnaissance des émotions au sein de ces personnages virtuels et maintenant l'intérêt se porte sur la capacité d'exprimer différentes attitudes sociales. Ces attitudes reflètent un style comportemental et s'expriment à travers différentes modalités du corps comme les expressions faciales, les regards ou les gestes par exemple. Nous avons proposé un modèle permettant à un agent de produire différents comportements non-verbaux traduisant l'expression d'attitudes sociales dans une conversation. L'ensemble des comportements générés par notre modèle permettent à un groupe d'agents animés par celui-ci de simuler une conversation, sans tenir compte du contenu verbal. Deux évaluations du modèle ont été conduites, l'une sur Internet et l'autre dans un environnement de réalité virtuelle, afin de vérifier que les attitudes étaient bien reconnues. / Embodied Conversational Agents are virtual characters which main purpose is to interact with a human user. They are used in various domains such as personal assistance, social training or video games for instance. In order to improve their capabilities, it is possible to give them the ability to produce human-like behaviors. The users, even if they are aware that they interact with a machine, are still capable of analyzing and identifying social behaviors through the signals produced by these virtual characters. The research in Embodied Conversational Agents has focused for a long time on the reproduction and recognition of emotions by virtual characters and now the focus is on the ability to express different social attitudes. These attitudes show a behavioral style and are expressed through different modalities of the body, like the facial expressions, the gestures or the gazes for instance. We proposed a model that allows an agent to produce different nonverbal behaviors expressing different social attitudes in a conversation. The whole set of behaviors produced by our model allows a goup of agents animated by it to simulate a conversation, without any verbal content. Two evaluations of the model were conducted, one on the Internet and one in a Virtual Reality environment, to verify that the attitudes produced are well recognized

[pt] Aplicações em Internet das Coisas (IoT) baseadas em agentes têm surgido como aplicações que podem envolver sensores, dispositivos sem fio, máquinas e softwares que podem compartilhar dados e que podem ser acessados remotamente. Essas aplicações vêm sendo propostas em vários domínios de aplicação, incluindo cuidados em saúde, cidades inteligentes e agricultura. Uma terminologia comumente utilizada para representar agentes embarcados inteligentes é embodied agents, a qual é proposta esse trabalho para projetar agentes para o domínio de IoT. Embodied agents significa agentes que possuem corpo, o qual pode ser definido pelos tipos de sensores e atuadores, e controlador, normalmente representada por uma rede neural artificial. Apesar da capacidade de reconfiguração ser essencial para embodied agents inteligentes, existem poucas tecnologias para suportar sistemas reconfigurfuaveis. Além disso, é necessário novas abordagens para lidar com as variabilidades dos agentes e do ambiente, e novos procedimentos para investigar a relação o entre o corpo e o controlador de um embodied agent, assim como as interações entre as mudanças do agente e do ambiente. Além da variabilidade do corpo e do controlador desses agentes, a exemplo do número e tipos de sensores, assim como o número de camadas e tipos de função de ativação para a rede neural, também é preciso lidar com a variabilidade do ambiente em que esses agentes estão situados. A fifim de entender melhor e esclarecer os conceitos de embodied agents, este trabalho apresenta um modelo de referência para embodied agents autoconfifiguráveis de IoT. A partir desse modelo de referência, três abordagens foram criadas para projetar e testar agentes embarcados reconfifiguráeis: i) um software framework para o desenvolvimento de embodied agents no domínio de internet das coisas; ii) uma arquitetura para configurar o corpo e controlador dos agentes de acordo com as variantes do ambiente; e iii) uma ferramenta para testar embodied agents. As abordagens foram avaliadas através de estudos de caso e experimentos em diferentes domínios de aplicação. / [en] Agent-based Internet of Things (IoT) applications have recently emerged as applications that can involve sensors, wireless devices, machines and software that can exchange data and be accessed remotely. Such applications have been proposed in several domains including health care, smart cities and agriculture. Embodied Agents is a term used to denote intelligent embedded agents, which we use to design agents to the IoT domain. Each agent is provided with a body that has sensors to collect data from the environment and actuators to interact with the environment, and a controller that is usually represented by an artificial neural network. Because reconfigurable behavior is key for autonomous embodied agents, there is a spectrum of approaches to support system reconfigurations. However, there is a need for approaches to handle agents and environment variability, and for a broad spectrum of procedures to investigate the relationship between the body and the controller of an embodied agent, as the interaction between the agent and the environment changes. In addition to the body and controller variability of these agents, such as those variations related to the number and types of sensors as well as the number of layers and types of activation function for the neural network, it is also necessary to deal with the variability of the environment in which these agents are situated. A discussion of the embodied agents should have some formal basis in order to clarify these concepts. Notwithstanding, this thesis presents a reference model for selfcon figurable IoT embodied agents. Based on this reference model, we have created three approaches to design and test self-configurable IoT embodied agents: i) a software framework for the development of embodied agents to the Internet of Things (IoT) applications; ii) an architecture to configure the body and controller of the agents based on environment variants; and iii) a tool for testing embodied agents. To evaluate these approaches, we have conducted diffierent case studies and experiments in difierent application domains.