Embodied agent

In artificial intelligence, an embodied agent, also sometimes referred to as an interface agent,[1] is an intelligent agent that interacts with the environment through a physical body within that environment. Agents that are represented graphically with a body, for example a human or a cartoon animal, are also called embodied agents, although they have only virtual, not physical, embodiment. A branch of artificial intelligence focuses on empowering such agents to interact autonomously with human beings and the environment. Mobile robots are one example of physically embodied agents; Ananova and Microsoft Agent are examples of graphically embodied agents. Embodied conversational agents are embodied agents (usually with a graphical front-end as opposed to a robotic body) that are capable of engaging in conversation with one another and with humans employing the same verbal and nonverbal means that humans do (such as gesture, facial expression, and so forth).

Embodied conversational agents

An automated online assistant providing customer service on a web page - an example of an embodied conversational agent.

Embodied conversational agents[2] are a form of intelligent user interface. Graphically embodied agents aim to unite gesture, facial expression and speech to enable face-to-face communication with users, providing a powerful means of human-computer interaction.


Face-to-face communication allows communication protocols that give a much richer communication channel than other means of communicating. It enables pragmatic communication acts such as conversational turn-taking, facial expression of emotions, information structure and emphasis, visualisation and iconic gestures, and orientation in a three-dimensional environment. This communication takes place through both verbal and non-verbal channels such as gaze, gesture, spoken intonation and body posture.

Research has found that users prefer a non-verbal visual indication of an embodied system's internal state to a verbal indication,[3] demonstrating the value of additional non-verbal communication channels. As well as this, the face-to-face communication involved in interacting with an embodied agent can be conducted alongside another task without distracting the human participants, instead improving the enjoyment of such an interaction.[4] Furthermore, the use of an embodied presentation agent results in improved recall of the presented information.[5]

Embodied agents also provide a social dimension to the interaction. Humans willingly ascribe social awareness to computers,[6] and thus interaction with embodied agents follows social conventions, similar to human/human interactions. This social interaction both raises the believability and perceived trustworthiness of agents, and increases the user's engagement with the system.[7] Rickenberg and Reeves found that the presence of an embodied agent on a website increased the level of user trust in that website; as well as this, the presence of the agent increased users' anxiety and affected their performance just as if they were being watched by a real human.[8] Another effect of the social aspect of agents is that presentations given by an embodied agent are perceived as more entertaining and less difficult than the same presentations given without an agent.[7] Research shows that perceived enjoyment, followed by perceived usefulness and ease of use, is the major factor influencing user adoption of embodied agents.[9]

One example result from a recent study indicates the power of a character when moderating search inquiries. When a character asked people to type search requests into a window, people used, on average, three more words in their requests (averaging about 7 words per inquiry) compared to identical requests made without a character. Character suggest that a conversational style is appropriate, resulting in higher liking for the interaction on the part of the user, and better accuracy for the engine generating the required results.[10]


This rich style of communication that characterises human conversation makes conversational interaction with embodied conversational agents ideal for many non-traditional interaction tasks. A familiar application of graphically embodied agents is computer games; embodied agents are ideal for this setting because the richer communication style makes interacting with the agent enjoyable. Embodied conversational agents have also been used in virtual training environments, portable personal navigation guides, interactive fiction and storytelling systems, interactive online characters and automated presenters and commentators.

See also


  1. Serenko, Alexander; Bontis, Nick; Detlor, Brian (2007). "End-user adoption of animated interface agents in everyday work applications" (PDF). Behaviour and Information Technology. 26 (2): 119–132. doi:10.1080/01449290500260538.
  2. Cassell, Justine; Prevost, Scott; Sullivan, Joseph; Churchill, Elizabeth (2000), Embodied Conversational Agents, Cambridge, MA: MIT Press
  3. Marsi, Erwin; van Rooden, Ferdi (2007), "Expressing uncertainty with a talking head in a multimodal question-answering system" (PDF), Proceedings of the Workshop on Multimodal Output Generation (MOG 2007), Aberdeen, UK, pp. 105–116
  4. Kipp, Michael; Kipp, Kerstin H.; Ndiaye, Alassane; Patrick (2006), "Evaluating the tangible interface and virtual characters in the interactive COHIBIT exhibit." (PDF), Proceedings of the International Conference on Intelligent Virtual Agents (IVA’06), Springer-Verlag, pp. 434–444
  5. Beun, Robbert-Jan; de Vos, Eveliene; Witteman, Cilia (2003), "Embodied conversational agents: Effects on memory performance and anthropomorphisation." (PDF), Proceedings of the International Conference on Intelligent Virtual Agents 2003, Springer-Verlag, pp. 315–319
  6. Nass, Clifford; Steuer, Jonathan; Tauber, Ellen R. (1994), "Computers are social actors", CHI ’94: Proceedings of the SIGCHI conference on Human factors in computing systems, New York, NY, USA: ACM Press, pp. 72–78
  7. 1 2 van Mulken, Susanne; André, Elisabeth; Müller, Jochen (1988), "The persona effect: How substantial is it?" (PDF), HCI ’98: Proceedings of HCI on People and Computers XIII, London, UK: Springer-Verlag, pp. 53–66
  8. Rickenberg, Raoul; Reeves, Byron (2000), "The effects of animated characters on anxiety, task performance, and evaluations of user interfaces.", CHI ’00: Proceedings of the SIGCHI conference on Human factors in computing systems, New York, NY, USA: ACM Press, pp. 49–56
  9. Serenko, Alexander (2008), "A model of user adoption of interface agents for email notification" (PDF), Interacting with Computers, 20 (4–5): 461–472, doi:10.1016/j.intcom.2008.04.004.
  10. "The Benefits of Interactive Online Characters" (PDF). Byron Reeves, Stanford University.

Further reading

External links

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