User modeling in human-computer interaction

A fundamental objective of human-computer interaction research is to make s ystems more usable, more useful, and to provide users with experiences fitt ing their specific background knowledge and objectives. The challenge in an information-rich world is not only to make information available to people at any time, at any place, and in any form, but specifically to say the "r ight" thing at the "right" time in the "right" way. Designers of collaborat ive human-computer systems face the formidable task of writing software for millions of users (at design time) while making it work as if it were desi gned for each individual user (only known at use time). User modeling research has attempted to address these issues. In this artic le, I will first review the objectives, progress, and unfulfilled hopes tha t have occurred over the last ten years, and illustrate them with some inte resting computational environments and their underlying conceptual framewor ks. A special emphasis is given to high-functionality applications and the impact of user modeling to make them more usable, useful, and learnable. Fi nally, an assessment of the current state of the art followed by some futur e challenges is given.