The justified user model: a viewable, explained user model*
R Cook and J Kay ?
Basser Department of Computer Science University of Sydney
This paper describes our experiences with giving users
access to the system's model of them. This access is
supported by a number of tools that enable a user to see
various forms of information: an overview display serves
as a navigation tool as well as a helpful summary; the
main model viewer program enables the user to see the
detailed model the system holds; the justification part
explains the system's reasoning about the user model; the
explanation subsystem provides a tailorable glossary of
the terms used in the user model description; and the
change facility allows the user to add their view of the
correct value of components of the model.
We outline the series of studies we have
conducted to learn how users respond to our visual
displays of a user model. These indicate a new purpose
for a user model as a useful communication tool that
enables users to find information that interests them as
well as to communicate the way that they would like to be
We also discuss some issues that arise from making the user model accessible. These affect the way that the programmer sees their relationship to the user. They also highlight the need to address different interpretations of a user model.
The user model is becoming increasingly important in a
number of classes of systems that are currently of
considerable interest: customised documentation,
teaching systems, information filtering and other tailored
There are many potential benefits from making a
* This work is supported by Telecom Australia Grant Reference Y05/04/34 and BLO/02/02/89
? R Cook is currently at Message Handling Systems, Newtown, Australia To appear UM94, 4th User Modeling Conference, Cape Code, USA>
user model accessible to the user it describes. This is on
the grounds of the user's right to access information
about themselves, the accountability it enforces on the
programmer creating and using the user model and the
benefit of having the user verify or correct the
information in the user model. In addition, there appear
to be educational benefits (Crawford and Kay 1992,
Crawford and Kay 1993). Others have argued the
importance of making complex systems more
comprehensible (for example, Fisher 1991; Maass 1983).
This paper describes viewer programs that enable
the user to see their user model, expressed in the um
representation (Kay 1990). From the very first, um was
designed to make the user model accessible to the user.
The viewers described here enhance practical
accessibility because they make it far easier to browse
through the model and to appreciate its overall structure
Our development of the accessible user model and associated viewer programs has been in the context of a number of projects. Our most extensive work has involved systems that support learning of the sam text editor (Pike, 1987). The primary goal in this work has been to enable users to become more effective sam users. We have created several coaching systems, each based on a different approach to teaching about sam (ParandehGheibi and Kay 1993). Another series of coaching experiments have taught users about Unix (Butler, 1992). We have also been studying various models of usage and learning of sam (Benyon, Kay and Thomas 1992). We have become particularly interested in the way that a viewable user model can, itself, be a useful tool. So, for example, one of our sam coaching systems allowed users access to the viewer programs. We expected that such access would enable these users to approach their learning about sam differently.