User-Adaptive Systems CSA3212: User-Adaptive Systems Topic 6: Adaptation Techniques Dr. Christopher Staff Department of Intelligent Computer Systems University of Malta 1

Aims and Objectives We will look at stages in the adaptation process and revisit the problems that AHS/UAS try to solve 2

Stages in the Adaptation Process Collect data about the user Process data to build/update user model Apply user model to provide the adaptation Last stage always fully automated in adaptive hypertext systems 1st and 2nd stages may require user intervention. Ideally, fully automated 3

Stages in the adaptation process If user and system need to co-operate to achieve adaptivity, then it is called collaborative user modelling From [Brusilovsky96] 4

What can be adapted? A hypertext is a collection of nodes that are connected by links So what can be adapted? The node content and user interface - adaptive presentation The node organisation and hyperspace representations (e.g., index, map, overview) - adaptive navigation 5

Generic approaches Adaptive Presentation Adaptive Navigation 6

Adaptive Presentation Anything to do with adapting how the presented material is displayed to users Examples Adapting the UI (more to do with adaptive user interfaces than adaptive hypertext per se) Modify data presentation so that it is presented in user's preferred choice (e.g., charts) 7

Adaptive Presentation More examples Automatically expand/collapse glossary items according to user's level of expertise Provide "trails" through hyperspace according to user's level of expertise Can be fairly complex - if user does not know concept A, then unlikely to know concept B, so concept B should also be automatically expanded 8

Adaptive Presentation Adaptive presentation can be useful in any adaptive hypertext system, but mostly used in Intelligent Tutoring Systems e.g., MetaDoc 9

Adaptive Navigation Focused around implicit link types in Web- based systems (ideally, link types are explicit) E.g., Letizia, WebWatcher, Personal WebWatcher, HyperContext Already identified implicit link types in previous lecture… navigational, context-free, context sensitive, index, TOC, glossary, map, ... 10

Problems Revisited Lost in HyperSpace Cognitive overload Complexity of the search space Search-browsing Static hypertext structure 11

Lost in HyperSpace Mark-up nodes to include link to landmark which user knows about Show relationship between landmark node and current node Reduce cognitive load on user 12

Cognitive overload Move (some) linking functions into AHS system by, e.g., providing "See Also" links Automatic/dynamic linking Reduce number of outlinks by removing links to non-relevant nodes Link recommendation services Add explanations/remove extraneous text 13

Complexity of the search space Removing links reduces the size of the search space Recommending links assists the user in deciding which links are likely to lead to relevant information Automatically modifying content enables readers to understand concepts at their level of understanding 14

Complexity of the search space Learn from user access paths to re-organise hyperspace Learn to associate user terminology with document content 15

Search-browsing Dynamic linking as a result of where user is combined with any stated query terms Recommend links (paths) to relevant documents 16

Static hypertext structure Users can modify structure, and/or system can learn from users What change(s) to hypertext systems would be required? IR systems? Dynamic hypertext systems 17

Adaptation Technologies 18

Direct Guidance Mainly through "Next" buttons! Can include link/path recommendation What are the pre-requisites? 19

Adaptive Sorting of Links Ordering links according to some ranking scheme On what basis? On which of the implicit link types can this be provided? 20

Adaptive Hiding of Links Hide links which would lead to non- relevant information What are the pre-requisites? In ITS systems? In generic AHSs? Identify implicit link types which support adaptive hiding 21

Adaptive Annotation of Links Mark-up anchor text/link description to explain the information at the destination of the link Description must be adaptive! 22

Adaptive Link Generation Must links be predetermined? Can automatically discover new links and add them permanently Must the destination of links be fixed? Add similarity-based links or recommended links (temporary) E.g., adapt navigational links to point to landmarks known to user 23

Insert/remove Text Fragments Automatically add or remove text fragments based on predetermined information about user’s knowledge of topics 24

Stretchtext Expand or contract text based on system’s knowledge of what user already knows Similar to insert/remove text, but different technology User can also interactively expand/contract text to give feedback to system 25

Dimming Fragments Rather than modifying the presentation of a familiar page (and confusing the user’s mental model of the page), dim rather than hide non-relevant information 26

Adaptation of Modality How should information be presented to user? Speech, music, animation, video, text? Assumes that information exist in different forms to begin with! 27