Politeness behaviors could affect individuals' decisions heavily in their daily lives and may therefore also play an important role in human-agent interactions. This study considers the impact of politeness behaviors made by a virtual agent, already in a small face-to-face conversational group with another agent, on a human participant as they approach to join it in a virtual environment displayed on a monitor. The agent uses five verbal and nonverbal politeness strategies, ranging from indirect and implicit to direct and explicit, in an attempt to influence the participant to join the group at an inconvenient location, which requires more time and effort than a direct route that would ignore the invitation of the agent. In addition to assessing the success of the strategies at influencing participant behavior, the participants' perception of the agent's persuasive behavior is assessed in relation to clarity, face loss, positive face, and negative face. Based on results from a within-subjects experiment with 30 participants, we found that more direct and explicit politeness strategies have a higher level of success when requesting a participant to join a small group at an inconvenient location, but sometimes negatively impact their perception of the agent. A positive politeness strategy was found to be the most effective for both persuasive success and maintaining a positive impression of the agent.

When modeling life-like Embodied Conversational Agents (ECAs), conveying politeness through verbal and nonverbal behaviors with persuasive intents is a significant challenge, as it underlies the conventional set of behavioral rules that govern human communication. In the present study, we explore the adherence to such rules in the context of joining a small, freestanding conversational group of agents in VR. In particular, we focus on the behavior adopted by participants while walking towards the agents, and on whether ECAs were treated in the same way human agents normally are. 45 test subjects were invited by an ECA to walk towards the group by applying one of six possible politeness strategies; after freely joining the group, they were asked to rate the agent's politeness according to four distinct aspects (Clarity, Face loss, Positive face, and Negative face). Across all strategies, in 48% of the trials participants were successfully persuaded to join the group at an inconvenient location. Out of those trials, participants adhered to social conventions by not crossing the convex empty space between the group members (o-space) in 75% of them on average. Additionally, analysis of verbal and nonverbal behaviors in ECAs shows that direct request strategies are more effective than indirect ones, although in some cases they may be perceived as less polite.

Multimodal communication is essential in human interactions, as it allows for a more comprehensive and nuanced exchange of information and emotions. The use of multiple communication channels such as speech, body language, and gaze can enhance the clarity and richness of the communication, leading to better understanding and more effective social interactions. This paper investigates the importance of multimodal expressive communication, specifically voice, arm gestures, and gaze, in regulating human-agent interaction when joining a group of two virtual agents in a virtual reality environment. One of the virtual agents in the group uses politeness behaviors based on Brown and Levinson's politeness theory to invite participants to join the group at the side further to them, even though a closer side is available. The study finds that a combination of all modalities (verbal, gaze, arm gesture) is more effective in persuading participants to join the group at the farthest side, and arm gestures alone are more effective than gaze behavior although they are perceived to be less polite. Furthermore, although verbal-only communication can be as persuasive as other modalities, it can place a greater cognitive load on participants. This increased cognitive load may lead to delayed responses in comparison to other modalities. The findings give insight to designers of human-agent interaction systems about the use of multiple communication channels, particularly nonverbal behaviors such as arm gestures, to enhance the effectiveness of persuasive communication but they also need to balance this with other factors such as the impression and perceived politeness of virtual agents.

Politeness is at the core of the common set of behavioral norms that regulate human communication and is therefore of significant interest in the design of Human-Robot Interactions. In this paper, we investigate how the politeness behaviors of a humanoid robot impact human decisions about where to join a group of two robots. We also evaluate the resulting impact on the perception of the robot's politeness. In a study involving 59 participants, the main (Pepper) robot in the group invited participants to join using six politeness behaviors derived from Brown and Levinson's politeness theory. It requests participants to join the group at the furthest side of the group which involves more effort to reach than a closer side that is also available to the participant but would ignore the request of the robot. We evaluated the robot's effectiveness in terms of persuasiveness, politeness, and clarity. We found that more direct and explicit politeness strategies derived from the theory have a higher level of success in persuading participants to join at the furthest side of the group. We also evaluated participants' adherence to social norms i.e. not walking through the center, or \textit{o-space}, of the group when joining it. Our results showed that participants tended to adhere to social norms when joining at the furthest side by not walking through the center of the group of robots, even though they were informed that the robots were fully automated. 

Politeness is critical for shaping human-human interactions and therefore seems an important consideration in human interactions with Embodied Conversational Agents (ECAs). However, the impact of artificially-generated politeness behaviors on humans in Virtual Environments (VE) is not clear. We explore the impact of immersiveness on the perceived politeness and consequent persuasive abilities of ECAs in a small group context. A user study with two main conditions, immersive and non-immersive, was conducted with 66 participants. In the immersive condition, participants were fully immersed in virtual reality (HMD, walking freely), while in the non-immersive condition, participants used a desktop computer interface (screen display, mouse and keyboard control). In both conditions, the primary agent in a group of two ECAs invited participants to join the group using six politeness behaviors derived from Brown and Levinson's politeness theory. While the results of the study did not indicate any significant differences between the immersive and non-immersive conditions in terms of persuasiveness and offensiveness, in the immersive condition, participants perceived the ECAs as less friendly and found their requests to be less clear. On the other hand, participants in the immersive condition reported a greater sense of freedom. Furthermore, the non-immersive condition showed higher adherence to social norms compared to the immersive condition. These findings emphasize the significance of examining immersiveness on the persuasiveness of ECAs and their perceived politeness and social adherence by humans in human-agent interactions within small groups.

Politeness and embodiment are pivotal elements in Human-Agent Interactions. While many previous works advocate the positive role of embodiment in enhancing Human-Agent Interactions, it remains unclear how embodiment and politeness affect individuals joining groups. In this paper, we explore how polite behaviors (verbal and nonverbal) exhibited by three distinct embodiments (humans, robots, and virtual characters) influence individuals' decisions to join a group of two agents in a controlled experiment (N=54). We assessed agent effectiveness regarding persuasiveness, perceived politeness, and participants' trajectories when joining the group. We found that embodiment does not significantly impact agent persuasiveness and perceived politeness, but polite behaviors do. Direct and explicit politeness strategies have a higher success rate in persuading participants to join at the furthest side. Lastly, participants adhered to social norms when joining at the furthest side, maintained a greater physical distance from humans, chose longer paths, and walked faster when interacting with humans.