Charles B. Callaway

Lifelike animated agents for knowledge - based learning environments can provide timely , customized advice to support students' problem solving . Because of their strong visual presence , they hold significant promise for substantially increasing students' enjoyment of their learning experiences . A key problemposed by lifelike agents that inhabit artificial worlds is deictic believability. In the same manner that humans refer to objects in their environment through judicious combinations of speech , locomotion , and gesture , animated agents should be able to move through their environment and point to and refer to objects appropriately as they provide problem - solving advice . In this paper we describe a framework for achieving deictic believability in animated agents . A deictic behavior planner exploits a world model and the evolving explanation plan as it selects and coordinates locomotive , gestural , and speech behaviors . The resulting behaviors and utterances are believable , and the references exhibit a lack of ambiguity . This approach to spatial deixis has been implemented in a lifelike animated agent , COSMO , who inhabits a learning environment for the domain of Internet packet routing . COSMO provides real - time advice to students as they escort packets through a virtual world of interconnected routers . Results of an informal focus group study with the COSMOagent suggest that the spatial deixis framework produces clear explanatory animated behaviors .