The role of user models in adaptive hypermedia systems

Computers have been used in education from the beginning. Educational systems have developed first from computer assisted learning systems to more complex intelligent tutoring systems and hypermedia systems. Intelligent tutoring systems are knowledge centred and are able to adapt the instructional sequence to the particular user. On the other hand, hypermedia systems are based on hypermedia and the user can freely browse the learning material. The last two technologies have merged into so called adaptive hypermedia systems. They are actually hypermedia systems, which incorporate some intelligent tutoring techniques. Therefore, they offer the freedom of exploratory learning, yet dynamically adapt to the individual user's knowledge level and learning goals, provide intelligent guidance, and support the user in acquiring knowledge. In intelligent tutoring systems, the adaptation is based on user modelling. Since adaptive hypermedia systems take the adaptation principles from intelligent tutoring systems, they also use user models for adapting the system to a particular user. Hence, the user model is one of the most important components for adaptation. Although the adaptation itself can be realised through different techniques, it is always based on the user model. In the paper, adaptive hypermedia systems and their general structure are described first. Then the role of a user model is presented together with the various approaches to user modelling in adaptive hypermedia systems. Finally, we investigate user modelling in different educational adaptive hypermedia systems.