Effects of Coupling in Human-Virtual Agent Body Interaction

Abstract

Abstract. This paper presents a study of the dynamic coupling between a user and a virtual character during body interaction. Coupling is directly linked with other dimensions, such as co-presence, engagement, and believability, and was measured in an experiment that allowed users to describe their subjective feelings about those dimensions of interest. The experiment was based on a theatrical game involving the imitation of slow upper-body movements and the proposal of new movements by the user and virtual agent. The agent's behaviour varied in autonomy: the agent could limit itself to imitating the user's movements only, initiate new movements, or combine both behaviours. After the game, each participant completed a questionnaire regarding their engagement in the interaction, their subjective feeling about the co-presence of the agent, etc. Based on four main dimensions of interest, we tested several hypotheses against our experimental results, which are discussed here.

Believability and Co-presence in Human-Virtual Character Interaction

“…The efforts made by both the autonomous agent and the WOz to adapt their behavior to that shown by the subject were not easily perceived and improved just a little the feeling of the interaction in condition SensitiveCoach. This confirms a similar result we obtained in the previous evaluation [2].…”

“…The role of the interaction itself is rarely studied in terms of co-presence (experiments often consist in evaluating an agent standing in its virtual environment without interacting with it) and we consider that it is important and maybe crucial to favor the feeling of this property. For instance, we conducted an evaluation in [2] and showed that the effort produced by the human to maintain a sensorimotor coupling with an interactive virtual agent improves effectively the feeling of co-presence. Nonetheless, in this previous study, the agent was not controlled by an autonomous decision model but by a WOz.…”

“…Mutual influence in human-human interaction can be very subtle and then very hard to consciously feel and evaluate; in human-virtual agent interaction it can be even harder since virtual agents are just an approximation of humans, however, in this context people have necessarily to pay attention to it. We opted for these two asymmetric interactions, that is one in which the users are mainly passive (they have principally to follow the agent lead) and one in which the users are mainly active (they have to make the agent follow them), because of a previous research study we conducted [2]. In this study we investigated people's perception of coupling during an interaction with a virtual agent and we noticed that the effort made by subjects to maintain the interaction could be enough to make them feel that they were coupled.…”

Aliveness metaphor for an evolutive gesture interaction based on coupling between a human and a virtual agent

“…To determine the running state of the interaction we use the concept of coupling. Coupling is defined as the continuous mutual influence between two individuals [16]. It possesses the capability to resist to disturbances, and compensates them by making the interaction evolve.…”

“…This definition is recursive since coupling exists because of the interactants' effort to "recover" it as its quality decreases. In [16] this effort is considered as an explanation of the improvement of the feeling of co-presence and engagement. Interactants measure coupling unconsciously and unconsciously they regulate it.…”