# Telepresence Social Robotics towards Co-Presence: A Review
## 2 Co-Presence Taxonomy
### Immersive Qualities
#### 2.1.2 Visual Representation  
In communication, the visual representation of interactants is a feature with an impact on social presence. Research has explored to what extent a representation form of the partner can contribute to the sense of social presence. Typically, studies manipulate (1) inclusion or no inclusion of visual representation and (2) the level of realism of the visual representation. The authors of [51] defined _realism_ as the extent to which a digital human representation behaves and appears like a real human. The overall concept is referred to as being based on three components: photographic, anthropomorphic, and behavior's communicative realism. The photographic component assesses the human-like visual appearance in a representation. Most studies report that the existence of a visual representation of the partner leads to higher social presence levels. In [52], participants who spoke with their partners through an avatar while shopping in a virtual mall felt a higher social presence in comparison with those who talked without seeing any partner representation. In [53], in an online support-seeker activity, users reported a higher sense of social presence when a profile picture of the counselor was present, as opposed to to not having a picture. The users also demonstrated a higher willingness to answer questions when the pictures were available. Anthropomorphism contributes to communicative realism because physical attributes such as the mouth, eyes, arms, and legs are involved in speech to generate facial expressions, gestures, and movements. It addresses the level of interpretation of what is not human or personal in terms of human or personal characteristics. Apart from behavioral realism, this manipulation focuses on the degree to which interactants are presented as human-like on the visual and auditory plane. For instance, users would interact via video as opposed to users who would interact via motion capture-controlled cartoons or by means of anthropomorphic agents or avatars vs. animated forms or emoji. Communicative realism addresses the degree to which a digital representation of the partner presents physical and social human-like behavior (e.g., breathing, natural blinking, and posture changes). Behavior realism studies manipulate the presence or absence of nonverbal behavior (e.g., animation) or the degree to which the nonverbal behavior of a virtual human resembles a real human (e.g., with or without eye gazing). The effect of communicative (behavioral) realism is more evident when the behavior of an agent or avatar reflects the awareness of the partner's presence (e.g., nodding at the right time, mutual gazing, or blushing). [PERSON] et al. [54] found that nodding the head of a computer-controlled agent during an interaction contributed to a higher degree of social presence in opposition to no nodding. In another study [55], the participants of an interaction with a virtual agent reported a higher level of social presence when they saw the agent blushing, a consequence of some mistake during a presentation. Study 1 in [50] found that the participants felt higher levels of social presence when the partner's representation (e.g., avatar) was able to maintain a mutual eye gaze in opposition to the absence of eye gazing. However, Study 2 in [50] realized that maintaining a mutual eye gaze for too excessive a time for video and avatars decreased social presence (i.e., an unnatural behavior). [PERSON]'s studies carefully tracked participants' nonverbal behavior using the head's orientation and position sensors, eye gaze trackers, a breath-monitoring chest belt, and data glove-based finger movement trackers. In the avatar's mediation condition, the tracked data were used to animate the avatars in real time (head and body movements, eye movements, and hand and finger movements). Their findings showed a similar activity in terms of visual attention and nonverbal activity either in video or in avatar conditions, contributing both positively and quite similarly to eliciting social presence.