adaptive hypermedia 2id20

Department of Computer Science

Adaptive Hypermedia2ID20

Prof. dr. Paul De Bra


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

AHA!


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)


Adaptive Hypermedia Systems

.

System User Model

Data about user

Adaptation effect

User Modeling

Adaptation


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


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.


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


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)


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


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


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!


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


Adaptive Presentation


Adaptive Navigation Support


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


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.…


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)


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


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


Example from Interbook

1. Concept role2. Current concept state

3. Current section state4. Linked sections state

4

3

2

1

√


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


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


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.


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

adaptive hypermedia 2id20

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