Adaptive Hypermedia 2ID20

1. Adaptive Hypermedia2ID20 Prof. dr. Paul De Bra

2. Course Topics • What is adaptive hypermedia? • Reference architecture • Example systems and applications • Evaluation of adaptive hypermedia • The AHA! system • Creating adaptive applications using AHA!

3. What is Adaptive Hypermedia? • Hypermedia • different media types used in a single application (text, images, sound, video, …) • non-linear structure with navigation through hyper-links • Adaptive • application forms a model of the context in which it is used (user, place, time, device, etc.) • application adapts to that context (can show different information, different media, different links, etc.) • adaptation and user modeling interact with each other (or else we say the application is adaptable, not adaptive)

4. Adaptive Hypermedia Systems

5. Why Adaptive Hypermedia? • Problems with (non-adaptive) hypermedia: • authoring hypermedia is difficult because of the navigational freedom of end-users • using hypermedia is difficult because the author did not anticipate the path the end-user follows • using hypermedia is also difficult because it is easy to get “lost in hyperspace” • Solutions through adaptive hypermedia: • compensate for unexpected comprehension problems due to the chosen navigation paths • warn users before following links that lead to problematic navigation paths • offer orientation support using adaptive overviews

6. Application Areas • Educational hypermedia systems • on-line course text, with on-line multiple-choice or other machine-interpretable tests • On-line information systems • information “kiosk”, documentation systems, encyclopedias, etc. • On-line help systems • context-sensitive help, (think of “Clippy”) • Information retrieval and filtering • adaptive recommender systems • etc.

7. Adaptive Educational Hypermedia • Origin: Intelligent Tutoring Systems • combination of reading material and tests • adaptive course sequencing, depending on test results • In Adaptive Educational Hypermedia: • more freedom for the learner: guidance instead of enforced sequence • adaptive content of the course material to solve comprehension problems when pages or chapters are read out of sequence • adaptation based on reading as well as tests

8. Adaptive On-line Information Systems • Examples: encyclopedia, documentation, but also shopping sites, airline reservation, etc. • goal: provide information about different topics • users are only interested in a few topics, not in studying the entire hyperspace • the system needs to know the user’s goal(s) in order to adapt (goal can be a topic, a product, an airline trip…) • the system also needs to adapt to the user’s knowledge and background, perhaps also location (e.g. departing city) • users need help most when the concepts they want do not match the concept structure of the application (e.g. they don’t know a close airport to the destination of their trip)

9. Adaptive On-line Help Systems • Like on-line information systems, but: • not independent but tied into an application (and called from that application) • (part of) the context is known through the application • often this context is the only information about the user needed to adapt the information • hyperspace is reasonably small • unfortunately adaptation does not turn bad help information into good, and it cannot compensate for missing help information • popular (bad) examples: Windows troubleshooter, Clippy

10. Adaptive Information Retrieval/Filtering • Adaptive Retrieval: • adaptively refine search requests • adaptively filter out non-relevant search results • update user model based on implicit or explicit relevance feedback • context information to be used can be a task, perhaps from a workflow system • Adaptive Filtering: • filters “incoming” information without the user explicitly asking for it • a “personalized view” interface for the Web can also be viewed as a filter • relies on relevance feedback to form and update a user model

11. The Future… Ambient Intelligence • Intelligent home (and office or building) • automatic heating/climate control • automatic lighting, kitchen, … • automatic communication redirection • adaptive information services and help • adaptive technology makes the technology “disappear” into the environment • a dream? not for long!

12. What Do We Adapt in AH? • Adaptive presentation: • adapting the information • adapting the presentation of that information • selecting the media and media-related factors such as image or video quality and size • Adaptive navigation: • adapting the link anchors that are shown • adapting the link destinations • giving “overviews” for navigation support and for orientation support

13. Adaptive Presentation

14. Adaptive Navigation Support

15. Canned Text Adaptation • Inserting/removing fragments • prerequisite explanations: inserted when the user appears to need them • additional explanations: additional details or examples for some users • comparative explanations: only shown to users who can make the comparison • Altering fragments • Most useful for selecting among a number of alternatives • Can be done to choose explanations or examples, but also to choose a single term • Sorting fragments • Can be done to perform relevance ranking for instance

16. Example from 2L690 • Before reading about Xanadu the URL page shows: • …In Xanadu (a fully distributed hypertext system, developed by Ted Nelson at Brown University, from 1965 on) there was only one protocol, so that part could be missing.… • After reading about Xanadu this becomes: • …In Xanadu there was only one protocol, so that part could be missing.…

17. Canned Text Adaptation (cont.) • Stretchtext • Similar to replacement links in the Guide hypertext system • Items can be open or closed; system decides adaptively which items to open when a page is accessed • Dimming fragments • Text not intended for this user is de-emphasized (grayed out, smaller font, etc.) • Can be combined with stretchtext to create de-emphasized text that conditionally appears, or only appears after some event (like clicking on a tooltip icon)

18. Adaptive Navigation Support • Direct guidance • like an adaptive guided tour • “next” button with adaptively determined link destination • Adaptive link generation • the system may discover new useful links between pages and add them • the system may use previous navigation or page similarity to add links • generating a list of links is typical in information retrieval and filtering systems

19. Adaptive Navigation Support (cont.) • Adaptive link annotation • all links are visible, but an “annotation” indicates relevance • the link anchor may be changed (e.g. in color) or additional annotation symbols can be used • Adaptive link hiding • pure hiding means the link anchor is shown as normal text (the user cannot see there is a link) • link disabling means the link does not work; it may or may not still be shown as if it were a link • link removal means the link anchor is removed (and as a consequence the link cannot be used) • a combination is possible: hiding+disabling means the link anchor text is just plain text

20. Example from Interbook 4 3 2 √ 1 1. Concept role 2. Current concept state 3. Current section state 4. Linked sections state

21. Adaptive Navigation Support (cont.) • Map adaptation • complete (site)maps are not feasible for a non-trivial hyperspace • a “local” or “global” map can be adapted by annotating or removing nodes or larger parts • a map can also be adapted by moving nodes around • maps can be graphical or textual • adaptation can be based on relevance, but also on group presence

22. What can we adapt to? • Knowledge of the user • initialization using stereotypes (beginner, intermediate, expert) • represented in an overlay model of the concept structure of the application • fine grained or coarse grained • based on browsing and on tests • Goals, tasks or interest • mapped onto the applications concept structure • difficult to determine unless it is preset by the user or a workflow system • goals may change often and more radically than knowledge

23. What can we adapt to? (cont.) • Background and experience • background = user’s experience outside the application • experience = user’s experience with the application’s hyperspace • Preferences • any explicitly entered aspect of the user that can be used for adaptation • examples: media preferences, cognitive style, etc. • Context / environment • aspects of the user’s environment, like browsing device, window size, network bandwidth, processing power, etc.

24. Web-based Adaptive Hypermedia • Client-server architecture using HTTP • only page accesses are registered (not scrolling, within-page scripting code or animations, etc.) • following a link activates a server-side program (CGI-script, Java Servlet, …) • the program uses the link URL and the user model to determine which page to return • the program performs content and link adaptation based on the user model (and some adaptation rules) • the program updates the user model taking into account that the user will read the presented information