Annotated Bibliography


Boston Dynamics, Inc.

Boston Dynamics Inc. (BDI) creates automated computer characters and engineering simulations for things that move, such as humans, animals, robots and electromechanical devices. They specialize in dynamic simulation coupled to 3D computer graphics. They are converging on interactive characters from the graphics and simulation vector rather than the AI and personality vector.

Cyberlife (makers of Creatures)

Creatures are Alife pets that you raise from eggs. Their technology is distinctive in its level of biological modeling. A Creature has a neural net for action selection, artificial biochemistry (including hormonal effects on the neural net), an immune system, and a reproductive system (a genome encodes for creature traits).

Extempo Systems

Extempo Systems was founded by Barbara Hayes-Roth, leader of the Virtual Theater Project at Stanford. Extempo is creating architectures and authoring tools for the creation of improvisational characters. Their first demo is Erin the bartender, a character who serves drinks and chats with customers in a virtual bar.

Fujitsu Interactive (makers of Fin Fin)

Fin Fin is a half-bird half-dolphin creature who lives in a world called Teo. Users interact with Fin Fin via a microphone, proximity sensor and mouse. Fin Fin is shy; a user has to slowly build up a relationship with Fin Fin over time. Fin Fin utilizes technology developed by the Oz group at Carnegie Mellon.

Mitsubishi Electric Research Laboratory


The COLLAGEN project has built a toolkit to support the construction of agents that collaborate with humans in accomplishing tasks. This toolkit embodies principles from collaborative discourse theory.


A middleware toolkit for building multi-user social virtual worlds. SPLINE was used to build the experimental virtual world Diamond Park .

Electronic Meeting Place

A multi-user virtual world inhabited by an autonomous agent named Mike.

Learning Stories

This project represents MERL's research into interactive narrative (drama). The focus is on stories in which a main character learns and changes during the events in the story. The model of user interaction is that of the Greek Chorus (Larry Friedlander). The members of the chorus provide multiple perspectives on the unfolding events. The first story implemented, about the Montgomery Bus Boycott, is called Tired of Giving In.

Motion Factory

Motion Factory is developing "Intelligent Digital Actor technology." Digital actors generate their own animation (motion) based on interactions with the environment. Motion Factory is an example of work converging on believable characters from the graphics community rather than the artificial intelligence community.

Na Software, Inc. (makers of Super Wan-Chan)

Super Wan-Chan is a virtual world containing four puppies that you raise to adulthood.

OZ Interactive

OZ Interactive makes 3D avatar worlds. They are building autonomous characters to inhabit their worlds. Early characters include Theresa, a moody expert on Greek mythology, and Angel, a helpful butler. From what I can tell, their agents are currently chatterbots.

Persona Project at Microsoft Research

The Persona project at Microsoft Research is developing the technologies required to produce conversational assistants-- lifelike animated characters that interact with a user in a natural spoken dialog. Their first prototype is Peedy, a character that responds to requests to play music. Gene Ball, a researcher in the Persona Project, organizes the conference Lifelike Computer Characters.

P.F. Magic (makers of Dogz, Catz, and Oddballz)

Dogz, Catz and Oddballz are autonomous pets that live on your screen.

Tamagocchi (from Bandai)

Tamagocchi is a small, egg shaped plastic toy with an LCD screen and 3 buttons. Users must nurture a creature that lives on the screen by feeding it, giving it medicine, disciplining it, and cleaning up excrement. If the user is negligent in these tasks, the creature dies. This product is a craze in Japan. While Tamagocchi possesses neither sophisticated personality nor sophisticated behaviors, it is an example of the powerful effect (in terms of effect on users) of even a small amount of lifelike behavior.


Zoeisis was recently founded by Joseph Bates (head of the Oz project) and Oz project alumni. Its goal is to build interactive story experiences utilizing believable agents.

Conferences and Workshops

Agents 97

February 1997. Marina Del-Rey CA.

Animated Interface Agents: Making Them Intelligent (Workshop)

Elizabeth Andre, James Lester, Thomas Rist, Aki Takeuchi, Co-chairs. IJCAI 1997. Nagoya Japan.

Artificial Intelligence, Artificial Life and Entertainment (Workshop)

Hiroaki Kitano, Joseph Bates, Co-chairs. AAAI 1994. Seattle, WA.

Believable Agents (Symposium)

Joseph Bates, Barbara Hayes-Roth, Brenda Laurel, Nils Nilsson, Co-chairs. Spring Symposia 1994. Stanford University.

Entertainment and AI/ALife (Workshop)

Hiroaki Kitano, Chair. AAAI 1996. Portland, OR.

Entertainment and AI/Alife (Workshop)

Hiroaki Kitano, Joseph Bates, Barbara Hayes-Roth, Co-chairs. IJCAI 1995. Montreal, Quebec.

Interactive Story Systems: Plot & Character (Symposium)

Joseph Bates, Barbara Hayes-Roth, Patti Maes, Co-chairs. Spring Symposia 1995. Stanford University

Lifelike Computer Characters

Gene Ball, Organizer. Last held October, 1996. Snowbird, UT.

Socially Intelligent Agents (Workshop)

Kerstin Dautenhan, Chair. Fall Symposia 1997. MIT, Cambridge MA.

Virtual Humans 1996 (a conference report)

Workshop on Interactive Fiction & Synthetic Realities

Joseph Bates, Chair. AAAI 1990. Boston, MA.


Characters, improvisation, and ...

A collection of links maintained by Craig Reynolds, famous for his creation of Boids, an artificial life simulation of flocking birds in which each bird's behavior is determined only by local rules. The collection is organized into the following categories: Characters, Creativity, Physically-Based Animated Figures, Games, Participatory Ecosystems, Robots, Agents, and Multi-Agent Systems.

Goal Processing and Emotion in AI

A collection of references to AI models of emotion.

Other virtual humans/ humanoid agents

A list of researchers primarily engaged in realistic (as opposed to employing artistic abstraction) human modeling. The list hangs off some project entitled Computer Aided Theory of Consciousness: An Essay in Experimental Digital Philosophy (page written in German).

Groups Collecting and Disseminating Research

Contact Consortium

A group that promotes avatar spaces.

Loebner Prize

The Loebner Prize contest, held each year, awards $2000.00 to the author of the program which does the best job passing a limited form of the Turing test.

Virtual Drama Society

A group that explores the future of immersive, dramatic storytelling.

Virtual Pet Home Page

A page discussing research and commercial products related to virtual pets.

Academic Research Projects

Affective Reasoning Project (Depaul University)

Led by Clark Elliott. The goal of this project is to build agents that can reason about emotion. Currently they have systems that can detect emotion in human voice, express emotion through facial expressions and speech inflection, and "have" emotions (in the sense that emotions detected in the user trigger emotions in the agent).

Center for Human Modeling and Simulation (University of Pennsylvania)

Home of Jack, a graphical human simulation package. The research at the Center is focused around building behavior and physics-based simulations of human figures.

The Cog Shop (MIT AI Lab)

Led by Rodney Brooks, the father of subsumption architecture. Rodney has been arguing for over a decade that the road to intelligence consists of building situated, embodied, broad agents (in his case, robots) which employ no semantic representations. Cog is a humanoid robot. As Cog interacts with the world using a body similar to a human body, it is hoped that Cog will learn to think the way humans do.

The Cognition and Affect Project (University of Birmingham)

A project led by Aaron Sloman and Glyn Humphries. The goal of this project is to explore the design space of AI architectures in order to understand the relationship between what kinds of architectures are capable of what kinds of mental phenomena. They are interested in the whole range of human mental states; in particular they wish to discover whether emotions are an accident of evolution or fundamental to the design of any resource-limited intelligent agent.

Entertainment Technology Center (Carnegie Mellon University)

Founded by Don Marinelli and Scott Stevens. They are charged with developing an entertainment technology program at CMU. Their current focus is Synthetic Interviews, an interactive video technology with which a user can have a conversation with some character.

Gesture and Narrative Language (MIT Media Lab)

Led by Justine Cassell. Using ideas from discourse theory and social cognition, this group designs agents which have discourse competence (e.g. knowing how to integrate gestures and speech to communicate, knowing how to take turns in a conversation, etc.).

IMPROV Project (NYU Media Research Lab)

This project is led by Ken Perlin and Athomas Goldberg . "The IMPROV Project at NYU's Media Research Lab is building the technologies to produce distributed 3D virtual environments in which human-directed avatars and computer-controlled agents interact with each other in real-time, through a combination of Procedural Animation and Behavioral Scripting techniques developed in-house." An example of convergence towards believable characters from the graphics side (vs. AI).

Interactive Cinema Group (MIT Media Lab)

A project at the Media Lab led by Glorianna Davenport. They study techniques for bringing interactivity to the traditional cinematic medium (with notable exceptions such as Tinsley Galyean's Dogmatic, which is set in a virtual world). In general, this involves breaking down a linear medium (such as video) into a database of clips, somehow annotating those clips, and then intelligently choosing the right clips at the right time as a user interacts with the system. The video may be accompanied by other media such as email (Lee Morgenroth's Lurker).

IntelliMedia (North Carolina State University)

Led by James Lester. This group focuses on intelligent multimedia. Currently they are focusing on animated pedagogical agents.

Jouhou System Kougaku Laboratory (University of Tokyo)

A robotics research lab, including remote-brained and humanoid robotics.

Julia (Carnegie Mellon University)

The home page for Julia, a chatterbot that lives in TinyMUDS.

Karl Wurst (Robotics and Puppetry, University of Connecticut)

Karl Wurst, in collaboration with the University of Connecticut's world-renowned Puppet Arts Program, is building robotic versions of the Woggles.

MIRALab (University of Geneva)

Led by Nadia Thalmann. This group works on virtual humanoids. Focus is on realistic modeling of human faces, movement, clothing, etc. Now starting to do work on autonomous systems.

Neo (University of Massachusetts)

Led by Paul Cohen. This group is building a baby that interacts in a simulated world. The goal is for the baby to learn the conceptual structure of the world through physical interaction.

Oz Project (Carnegie Mellon University)

Led by Joseph Bates, founder of Zooesis. The goal of the Oz project is to build interactive story worlds containing personality rich, believable characters. A drama manager ensures that the user experiences a high-quality story.

Phil Agre

Phil Agre and David Chapman developed Pengi, a system which played the video game Pengo. Pengi is an instance of "alternative AI": it employed reactive behaviors and deictic (context dependent) representations. Phil has written elegantly on why classical AI is inappropriate for building agents which engage in situated, embodied, routine activity.

Selmer Bringsjord

Primarily a philosopher of AI, Selmer also does research in story generation. His forthcoming book, AI, Story Generation and Literary Creativity: The State of the Art will describe BRUTUS, his latest story generation system.

Social Responses to Communication Technology (Stanford University)

A project led by Clifford Nass and Byron Reeves. They are studying the way people apply social rules and schemas to their interactions with technology.

Software Agent Group (MIT Media Lab)

Led by Patti Maes. The software agent group explores the use of autonomous agents in a wide variety of contexts. Much of their work tends to have an artificial life flavor (by which I mean that the work focuses on useful behavior emerging out of the interactions of many software agents). Agents as synthetic characters was explored by Bruce Blumberg in the ALIVE and Hamsterdam projects. The synthetic character work has how shifted to a new group being started by Bruce. He developed an ethologically motivated action selection mechanism to drive his synthetic characters.

Virtual Environments for Training (USC Information Sciences Institute)

Led by W. Lewis Johnson. This group has built a pedagogic agent named Steve that trains humans in virtual worlds. Steve teaches people how to perform tasks, gives advice as it watches users perform tasks, and answers student's questions.

Virtual Theater Project (Stanford)

Led by Barbara Hayes-Roth, founder of Extempo. The metaphor informing their work is that of an improvisational actor. That is, they build actors who try to improvise behavior in different situations. An actor's improvisational choices may be influenced by an explicitly specified personality (a set of values along some dimensions of personality). They are also exploring how a human might exert high level control over one of these actors.

Waseda Humanoid Project (Waseda University)

They are building a humanoid robot including sensing, recognition, expression and motion subsystems.


Articles written by the OZ Project (CMU)

On-line articles available about the OZ project. Articles include overall descriptions of the goals of the project, the action architecture, the emotion architecture, and natural language generation (for the text based worlds).

Articles written by the Software Agents Group (MIT Media Lab)

On-line articles from the Software Agents Group. Articles relevant to believable agents are listed under "Modeling Synthetic Characters: Applications and Techniques." Articles include descriptions of ALIVE, action-selection architectures, and the role of artificial life in entertainment.

Articles written by the Virtual Theater Project (Stanford)

On-line articles available about the Virtual Theater Project. Articles include descriptions of their approach to emotion, personality, and user control of improvisational puppets.

Special Issue on Situated Cognition

Cognitive Science 17, 1993.

The articles in this issue discuss the relationship between "alternative AI" (sometimes called behavioral AI, or situated action) and "classical AI." Simon and Vera wrote an article in which they argue that all of the specific work that falls under the rubric of situated action can not be construed as refutations of the physical symbol system hypothesis. Situated action is just a subset of symbolic AI which focuses on perception and motor control. The rest of the issue consists of articles written by various situated action proponents responding to Simon and Vera's article.

The Dynamic Structure of Everyday Life

Phil Agre. A.I. Memo 1085. Artificial Intelligence Lab. MIT. October 1988.

Agre's Ph.D. thesis. Describes Pengi, a program that can play a video game called Pengo. Pengi is able to play the game without employing any traditional planning.

What are plans for?

Phil Agre and David Chapman. A.I. Memo 1050a. Artificial Intelligence Lab. MIT. September 1988.

Argues for a view of plans as plans-for-communication (as opposed to the classic view of plans-as-programs).

I Had a Dream: AAAI Presidential Address, 19 August, 1985

Woody Bledsoe. AI Magazine, Spring 1986, pp 57-61.

Bledsoe describes the dream that brought him (and many AI researchers) into AI research in the first place: the dream of building computer companions.

Intelligence Without Reason

Rodney Brooks. A.I. Memo 1293. Artificial Intelligence Lab. MIT. April 1991.

Argues for a situated, embodied, semantic-symbol-free approach to achieving intelligence in artificial systems.

Elephants Don't Play Chess

Rodney Brooks. Robotics and Autonomous Systems 6, 1990. pp. 3-15.

Argues for a situated, embodied, semantic-symbol-free approach to achieving intelligence in artificial systems.

Neo: Learning Conceptual Knowledge by Sensorimotor Interaction with an Environment

Paul R. Cohen, Marc S. Atkin, Tim Oates, and Carole R. Beal. Proceedings of the First International Conference on Autonomous Agents, pp. 170-177. Marina del Rey, CA. February 5-8, 1997.

Describes a simulated baby who learns concepts by "physically" interacting with a simulated world. This work comes out of the Neo project.

Descartes' Error: Emotion, Reason and the Human Brain

Antonio Damasio. Avon Books. 1994.

Describes recent research findings in neuropsychology which seem to indicate that emotion plays a fundamental role in human intelligence. Much of traditional cognitive psychology and artificial intelligence has assumed that emotion is not critical to understanding intelligence.

The Art of Dramatic Writing: Its Basis in the Creative Interpretation of Human Motives

Lajos Egri. Simon and Schuster. 1946.

Describes how plays work via a theory which relates character, motive and story.

I Picked Up Catapia and Other Stories: A Multimodal Approach to Expressivity for "Emotionally Intelligent" Agents

Clark Elliott. Proceedings of the First International Conference on Autonomous Agents, pp. 451-457. Marina del Rey, CA. February 5-8, 1997.

Describes an agent which communicates emotionally with people using speech recognition, text-to-speech conversion, real-time morphed schematic faces and music. This work comes out of the Affective Reasoning Project.

An Open Architecture for Robot Entertainment

Masahiro Fujita and Koji Kageyama. Proceedings of the First International Conference on Autonomous Agents, pp. 435-442. Marina del Rey, CA. February 5-8, 1997.

Describes a standard defined by Sony Corporation for household entertainment robots.

Narrative Guidance of Interactivity

Tinsley A. Galyean III. Ph.D. thesis, Media Arts and Sciences, MIT, June 1995.

Creatures: Artificial Life Autonomous Software Agents for Home Entertainment

Stephen Grand, Dave Cliff, and Anil Malhotra. Proceedings of the First International Conference on Autonomous Agents, Marina del Rey, California, USA, February 1997, pp 22-29.

Describes the architecture behind virtual pets which employ Alife technology (see Cyberlife).

A Face Robot Able to Recognize and Produce Facial Expression

Fumio Hara and Hiroshi Kobayashi. Proceedings of the 1996 IEEE/RSJ International Conference on Intelligent Robots and Systems, Senri Life Science Center, Osaka, Japan, November 4-8, 1996, pp 1600-1607.

Describes a robot with a human-like face that can recognize and produce human facial expressions.

Acting in Character

B. Hayes-Roth, R. van Gent, D. Huber. Proceedings of the AAAI Workshop on AI and Entertainment, 1996.

Describes a system that portrays a role change between a master and a servant. The master and servant improvise within the constraints of a script.

Real-Time Vision-Based Control of Swing Motion by a Human-form Robot Using the Remote-Brained Approach

Masayuki Inaba, Ken'ichiro Nagasaka, Fumio Kanehiro, Satoshi Kagami, Hirochika Inoue. Proceedings of the 1996 IEEE/RSJ International Conference on Intelligent Robots and Systems, Senri Life Science Center, Osaka, Japan, November 4-8, 1996, pp 15-22.

Describes a humanoid robot that can swing on a swing using visual tracking for control.

Chuck Amuck: The Life and Times of an Animated Cartoonist

Chuck Jones. Farrar, Straus and Giroux. 1989.

The autobiography of Chuck Jones, an animator at Warner Bros. Describes the Warner Bros. approach to creating characters and story.

Dramatic Presence

Margaret Kelso, Peter Weyhrauch, Joseph Bates. Presence: The Journal of Teleoperators and Virtual Environments, Vol. 2, Num. 1, MIT Press, Winter 1993.

Describes a series of live experiments to test the effect of interactive freedom on the dramatic experience. Also includes a description of plot graphs.

Computers as Theater

Brenda Laurel. Addison-Wesley, 1991.

Draws on Aristotle's theory of drama to define a new approach to designing dramatic human-computer interfaces.

Toward the Design of a Computer-Based Interactive Fantasy System

Brenda Laurel. Ph.D. thesis, Drama department, Ohio State University, 1986.

Describes a hypothetical drama manager that guides an interactive story experience.

Story Telling as Planning and Learning

Michael Lebowitz. Poetics 14, 1985. pp. 483-502.

Describes the use of plan-like plot-fragments in UNIVERSE, a system that writes soap opera-like stories.

Creating Characters in a Story-Telling Universe

Michael Lebowitz. Poetics 13, 1984. pp. 171-194.

Describes the representations of characters in UNIVERSE, a system that writes soap opera-like stories.

Increasing Believability in Animated Pedagogical Agents

James Lester and Brian Stone (IntelliMedia). Proceedings of the First International Conference on Autonomous Agents, pp. 16-21. Marina del Rey, CA. February 5-8, 1997.

Describes a competition-based behavior sequencing engine which produces life-like behavior while maintaining pedagogical appropriateness (e.g. don't distract a learner with some fancy behavior when they are problem solving).

Believable Agents

A. Bryan Loyall. Ph.D. thesis, Tech report CMU-CS-97-123, Carnegie Mellon University, May 1997.

Describes requirements for believability derived from the character arts. These requirements motivate the description of Hap, an agent language designed to facilitate writing believable agents. The thesis then describes several examples of agents written in Hap. Finally, a method for doing believable, embodied natural language generation in Hap is described. This work is part of the Oz Project.

Personality-Rich Believable Agents That Use Language

A. Bryan Loyall and Joseph Bates. Proceedings of the First International Conference on Autonomous Agents, pp. 106-113. Marina del Rey, CA. February 5-8, 1997.

Describes the integration of embodied natural language generation into a behavioral agent architecture. "We describe our approach, and show how it leads to agents with properties we believe important for believability, such as: using language and action together to accomplish communication goals; using perception to help make linguistic choices; varying generated text according to emotional state; varying generated text to express the specific personality; and issuing the text in real-time with pauses, restarts and other breakdowns visible." This work is part of the Oz Project.

Understanding Comics: The Invisible Art

Scott McCloud. HarperCollins. 1993.

Written in comic book form, this book describes the semiotics of comics.

The Metanovel

James Meehan. Ph.D. Dissertation. Yale University. 1976.

Describes a system that generates Aesop fable-like stories. It generates stories by using planning to achieve the goals of characters.

A Methodology for Building Believable Social Agents

W. Scott Neal Reilly. Proceedings of the First International Conference on Autonomous Agents, pp. 114-121. Marina del Rey, CA. February 5-8, 1997.

Describes a methodology for building social behaviors on a character-by-character basis. The philosophy behind this approach is that generic taxonomies of social behavior and personality are inappropriate for building believable characters. This work comes out of the OZ Project.

Believable Social and Emotional Agents

W. Scott Neal Reilly. Ph.D. thesis. Tech report CMU-CS-96-138, Carnegie Mellon University, May 1996.

Describes a system that maintains emotional state and a methodology for incorporating emotion into the behaviors of believable agents. The thesis then describes a methodology for building believable social behaviors. This work is part of the Oz Project.

Improv: A system for Scripting Interactive Actors in Virtual Worlds

Ken Perlin, Athomas Goldberg. Proceedings of SIGRAPH 96, pp. 205-216. New Orleans, LA. Aug. 1996.

Describes the interactive character architecture of the Improv project. An animation engine manipulates the control points of a graphical model. A behavior engine allows the user to specify higher level scripts which control the characters motions. The scripts are written in an English-like scripting language (reminiscent of HyperTalk).

Interval Scripts: a Design Paradigm for Story-Based Interactive Systems

Cladio Pinhanez. Proceedings of CHI97, Atlanta, GA, USA, March 22-27, pp 287-294.

Describes a method whereby interaction can be scripted with a temporal calculus that represents the relationships between intervals. A constraint propagation mechanism is used to determine the temporal value (past, now, future, or some mixed state) of each interval. Intervals can be associated with sensors and effectors.

COLLAGEN: When Agents Collaborate with People

Charles Rich and Candace L. Sidner. Proceedings of the First International Conference on Autonomous Agents, pp. 284-291. Marina del Rey, CA. February 5-8, 1997.

Describes a toolkit that supports the construction of agents who follow the rules of collaborative discourse. This work comes out of MERL.

The Illusion of Life: Disney Animation

Frank Thomas and Ollie Johnston. Hyperion. 1981.

Written by two Disney animators, this book describes the history of animation at Disney and what techniques the animators developed to make their characters seem believable. This book has been highly influential in the OZ Project at CMU.

Communicative Humanoids: A Computational Model of Psychosocial Dialogue Skills

Kristinn Thorison. PhD Thesis. MIT Media Laboratory, 1996.

Describes a system called Gandalf that models human dialog competence in order to communicate with a human using speech and gesture in realtime.

Virtual Actors that Can Perform Scripts and Improvise Roles

Peter Wavish and David Connah. Proceedings of the First International Conference on Autonomous Agents, pp. 317-322. Marina del Rey, CA. February 5-8, 1997.

Describes a script based architecture developed at Phillips Research Labs for controlling virtual characters.

ELIZA -- A computer program for the study of natural language communication between man and machine

J. Weizenbaum. Communications of the ACM 9(1):36-45, 1966.

Original paper describing ELIZA, a template-based pattern-matching program that simulates the conversational patterns of a non-directive therapist.

Guiding Interactive Drama

Peter Weyhrauch. Ph.D. thesis, Tech report CMU-CS-97-109, Carnegie Mellon University, January 1997.

Describes the Oz drama manager, a search-based system for guiding an interactive story experience. This work is part of the Oz project.