Adaptable vs. Adaptive Hypermedia
Many hypermedia systems can be customized to some extent.
Some of these customizations have no effect on the real or perceived
content of nodes or the link structure. In an adaptable
hypermedia system the user can perform customizations that do
influence the presentation of information or the true or perceived
link structure. Examples include:
- In the course text for TUE course 2M350: Graphical User-Interfaces
(URL: http://wwwis.win.tue.nl/2M350/)
the user can set a "verbose" parameter to select between verbose (full text)
presentation or terse (viewgraph-style) presentation of information.
- In the AVANTI system (see
http://www.avanti-acts.org/)
adaptability is aimed at providing information for elderly and
disabled people. This means offering a different access and presentation
(including other input/output devices like a braille display) but also
different information (including access to physical buildings or sites
for people with disabilities).
- In the AHA system (used for this course) the user can change color
preferences in such a way that "undesirable" link anchors are either
annotated visibly or are hidden. When some links are hidden the
user gets the impression that these links do not exist. The perceived
link structure thus changes (but the real link structure remains the same).
In an adaptable hypermedia system the user needs to set a number of
variables explicitly through a questionnaire or initial "test".
From this input the system deduced which stereotype applies
to the user. Most adaptable hypermedia systems are able to handle
only a small number of stereotypes. Also, once the stereotype of the
user is determined it never changes unless the user takes an explicit
action, possibly through the questionnaire again.
Most adaptive hypermedia systems are also adaptable.
The user can initialize the user model through a questionnaire,
and the system will monitor how the user's knowledge state, preferences,
goals and experience evolve over time.