Navigational adaptation techniques
Navigational adaptation is provided by changing the boundaries, either by shrinking or enlarging, of the hyperspace by link manipulation. Link manipulation can be used to suggest the most relevant link to follow, to activate or de-activate certain links or to dynamically generate new link settings. Techniques to accomplish link manipulation can be grouped into five categories. These are direct guidance, ordering, hiding, annotation and mapping. The most widely used adaptive navigational techniques which support both the local and global approach are direct guidance and link sorting.
1. Direct guidance: This is the simplest adaptive navigational aid. With this technique the system suggests to the user the best node to visit next as in WebWatcher (Armstrong et al 1995) or the next node as in ISIS-Tutor (Brusilovsky and Pesin 1994). Direct guidance does not give the user the flexibility of ignoring the systems suggestion (Brusilovsky, 1996).
2. Ordering: This technology sorts or reorders the links on a specific page or topic according to the user model. The applicability of adaptive sorting in hypertext systems is very limited. It can never be used with contextual links and maps (Brusilovsky 1996). However, this method has been used a number of hypertext systems which employ information retrieval such as HYPERFLEX (Kaplan et al 1993) and the POP hypertext help system (Hook et al 1996).
3. Hiding: This is based on hiding or disabling links to pages which appear to be irrelevant to the users requirements. This also reduces the possibility of cognitive overload by controlling the navigational hyperspace. Because hiding allows for a gradual exposure of the hyperscape, it can be effectively used in educational hypermedia systems as in ISIS-Tutor. This technique can be applied to non-contextual links, indexes, maps, menus, icons and contextual links by changing hotspots into normal text.
4. Annotation: With this technology links can be enriched with extra comments. Annotated links can provide users with more information about the links destination before selection. Annotations can take the form of text and icons or can be encoded by colours, different font sizes or typefaces. Adaptive colour annotation is used in WWW browsers to indicate visited and non visited links. ISIS-Tutor uses six colour annotations according to the appropriate user model.
5. Mapping: A map allows a user to understand the overall structure of the hyperspace and also to locate themselves within it. Hiding, annotation and direct guidance can be used to enhance a map. This technique can be used both locally and globally.
Table of Contents
Authored by Serengul Smith
School of Computing Science Middlesex University
Revised: September 1998