@phdthesis { prada05, abstract = {In recent years, virtual environments have evolved from single user and single agent, to multi-user and multi-agent, thus, engaging simultaneously users and synthetic characters all interacting, collaborating or competing with each other. This new scenario created new challenges for the users’ interaction with the environment, in particular, for their interaction with the autonomous synthetic characters. To engage in successful and believable interactions the synthetic characters must be able to show a coherent set of behaviours responsive to the user’s actions. For example, in scenarios where users and synthetic characters engage the resolution of collaborative tasks, thus, interacting as a group, it is very important that their interactions follow a believable group dynamics. Therefore, focusing on this problem, we have developed a model that supports the creation of a believable group dynamics on a group of synthetic characters, inspired by theories of group dynamics developed in human socio-psychological sciences. The dynamics is driven by a characterization of the different types of interactions that may occur in the group and deals with both the socio-emotional interactions and the task related interactions. We have implemented the model into the behaviour of synthetic characters that collaborate, in a group, with the user in the resolution of tasks within a virtual environment. The collaborative task was developed in the form of a computer game that engages the user in a group with four synthetic characters constituted to solve together puzzle like challenges. This game was used in an experiment conducted to assess the effects of the model on the user inter- action with the group. The results showed that the model had a positive effect on the users’ interaction experience, specially in their trust and identification with the group.}, address = {Lisbon, Portugal}, keywords = {synthetic characters, group dynamics, collaboration, human-computer interac- tion, multi-agent systems, virtual environments}, month = {December}, school = {Instituto Superior Técnico, Universidade Técnica de Lisboa}, title = {Teaming Up Humans and Synthetic Characters}, year = {2005}, author = {Rui Prada} }