After having spent ten years studying verbal and non-verbal aspects of human communication through microanalysis of human data, Cassell began to bring her knowledge of human conversation to the design of computational systems, designing the first autonomous animated agent with speech, gesture, intonation and facial expression in 1994 during a sabbatical spent at the University of Pennsylvania Center for Human Simulation.

Along with her students, she is currently implementing the newest generation of Embodied Conversational Agent -- "Rea" -- a life-size animated humanoid figure on a screen that can understand the conversational behaviors of the human standing in front of it (using computer vision techniques), and respond with appropriate speech, animated hand gestures, body movements, and facial expressions of its own. The architecture for this new "conversationally intelligent" agent is based on an analysis of conversational functions, allowing the system to exploit users' natural speech, gesture and head movement in the input to organize conversation, and to respond with automatically generated verbal and nonverbal behaviors of its own.

As well as being a pioneer in this new research area of Embodied Conversational Agents, Justine Cassell has also played a key role in investigating the role that technologies such as these play in children's lives. Interactive technologies such as Sam, the virtual storytelling peer can have the potential to encourage children in creative, empowered and independent learning. They can also demonstrate ways for new technology to live away from the desktop, supporting children's full-bodied, collaborative, social play-based learning. Cassell and her students have built a suite of Story Listening Systems that encourage children to tell stories and in doing so to practice decontextualized language of the kind that is essential for literacy.

Justine Cassell's other current research and projects include:

• technological toys for both boys and girls that encourage them to express aspects of self-identity that transcend stereotyped gender categories;

• technologies that are accessible both to children with high technological fluency, and children with no technological fluency. Justine Cassell was the director of Junior Summit '98, a program that brought together online more than 3000 children from 139 different countries to discuss how technology could be used to help children, and then gathered 100 of those children in Boston for a 5 day summit, where they presented their ideas to world leaders and international press.

Professor Cassell has spoken about her research at academic conferences around the world, including AAAI, ACL, CHI, Cognitive Science, IJCAI, and SIGGRAPH, as well to industry leaders in companies such as IBM, Lego, Mattel, Philips, Toshiba and Xerox Parc.