A Glass Box Approach to Adaptive Hypermedia A GLASS BOX APPROACH TO ADAPTIVE HYPERMEDIA Kristina H k A Dissertation submitted in partial completion of the requirements for the Degree of Doctor of Philosophy Stockholm University Department of Computer and Systems Sciences October 1996 Department of Computer and Systems Sciences Swedish Institute of Computer Science The HUMLE group Electrum 230Box 1263 S 164 40 KistaS 164 28 Kista SwedenSweden DSV 96 018SICS Dissertation Series 23 ISSN 1101 8526ISSN 1101 1335 ISRN SU KTH DSV R 96 18 SEISRN SICS D 23 SE Doctoral thesis Stockholm University ISBN 91 7153 510 1 Copyright 1996 by Kristina H k Printed by Akademitryck AB Edsbruk 1996 To Sverker Adam and Axel with love Abstract Information overflow and navigation in large hyperspaces is becoming a familiar problem to a growing user population Adaptive hypermedia can be used to improve users information retrieval behaviour and reduce the information overflow problem In our adaptive hypermedia prototype POP1 designed for a large Intranet database we use stretchtext and hotwords in order to hide some information from the users immediate view We infer users information seeking tasks from their interactions with the system and base our decision on what to hide on what is required by their task This enables us to reduce the amount of information and only display the most relevant information The design of the system is based on empirical studies of the users and their tasks Our approach to adaptivity is primarily directed at reducing the problem of information overflow At the same time we are concerned with how to make the adaptive behaviour understandable to the user and give the user control over the adaptive mechanisms There should be a balance between user and system controlled adaptivity Our design basis is the black box in a glass box metaphor we hide the complex behaviour of the adaptive system in the black box and show a fairly simple model to the user in the glass box The resulting system has been evaluated in a controlled comparative study and the results show that the adaptive system was preferred over the non adaptive variant by the subjects Furthermore it required fewer actions within the page and the choice of information made by the system influenced subjects solutions KEYWORDS Adaptive hypermedia user modelling user centred design empirical evaluation task adaptation computer aided adaptation self adaptive system 1 POP PUSH Operational Prototype developed in the PUSH Plan and User Sensitive Help project i THESIS DRAFT PREFACE In January 1993 I was sitting in a rented car travelling through the Everglades national park in Florida Together with me in the car were Nils Dahlb ck from Link ping and two of my colleges from SICS Annika W rn and Jussi Karlgren We had just attended the Internal Workshop on Intelligent User Interfaces IWIUI held at Disneyworld in Orlando During the trip through the Everglades we were discussing intensively and with quite some emotional involvement what the research problem s in the PUSH Plan and User Sensitive Help project was and should be The deadline for applying for money from NUTEK was close and we wanted to approach the former Ellemtel Utvecklings AB2 with our ideas to see if they wanted to co operate and contribute to the project After seeing some of the systems presented at the IWIUI conference we saw that the time was ripe to introduce some usability demands on the intelligent interface systems and move them from their laboratory settings solving toy world examples We also saw a lack of empirical evaluation of the usefulness of adaptive systems We decided that we wanted to build an intelligent help system for a real world industrial problem We wanted to end the project with a comparative study were we would study how much the intelligent adaptive parts of the system were contributing with in solving the help problem We wanted the system to have a rich interface both graphics and text In January 1993 we did not know that the WWW revolution was about to take place so when imagining the interface to the help system we did not picture an adaptive hypermedia system with a WWW interface which is what we ended up with three years later Some of the issues and ideas that came up during the car trip through the Everglades and during the following discussions back in Sweden with Prof Carl Gustaf Jansson and Rolf Leidhammar at the former Ellemtel Utvecklings AB were interesting enough to cause NUTEK and Ellemtel to together with SICS put up the necessary funding for the project The problems we set out to investigate lead to the research results presented in this thesis Of course the ideas we put into the PUSH project had their roots in the experiences and results that members of the project brought with them rather than invented in the car in the Everglades I brought experiences mainly from the Prometheus project where I together with Annika W rn Carl Brown Per Lindevall and Jussi Karlg