We have evaluated an adaptive hypermedia system, PUSH, and compared it to a non-adaptive variant of the same system. Based on an inferred information seeking task, PUSH chooses what to show and what to hide in a page using a stretchtext technique, thus attempting to avoid information overload. We studied how successful the subjects were in retrieving the most relevant information, and found that the subjects’ solutions were influenced by the choice made by the adaptive system. We also studied how much the adaptivity reduced the amount of actions needed, and found that subjects made substantially fewer actions in the adaptive case. A third measurement was the subjects subjective preferences for the adaptive or the non-adaptive system, were we found that the subjects clearly preferred the adaptive system. It seems as if it requires less decisions on behalf of the subject, thereby reducing their cognitive load.

. We describe the user modeling and personalization techniques adopted in SETA, a prototype toolkit for the construction of adaptive Web stores which customize the interaction with users. The Web stores created using SETA suggest the items best fitting the customers' needs and adapt the layout and the description of the store catalog to their preferences and expertise. SETA uses stereotypical information to handle the user models and applies personalization rules to dynamically generate the hypertextual pages presenting products. The system adapts the graphical aspect, length and terminology used in the descriptions to parameters like the user's receptivity, expertise and interests. Moreover, it maintains a model associated with each person the goods are selected for; in this way, multiple criteria can be applied for tailoring the selection of items to the preferences of their beneficiaries. Keywords: user modeling, personalized information presentation, customization of Web stores, ...

The development of user-adaptive systems is of increasing importance for industrial applications. User modeling emerged from the need to represent in the system knowledge about the user in order to allow informed decisions on how to adapt to match the user's needs. Most of the research in this field, however, has been theoretical, "top-down." Our approach, in contrast, was driven by the needs of the application and shows features of bottom-up, user-centered design.

. We have created a student model which dynamically collects information about a student's problem solving ability, acquisition of new topics and retention of earlier topics. This information is provided to the tutor and used to generate new problems at the appropriate level of difficulty and to provide customized hints and help. Formative evaluation of the tutor with 20 students provides evidence that the student model constructs problems at the correct level of difficulty. The problem generation technique is extensible for use in other problem-based domains. This paper describes the design and implementation of the student model and illustrates how the tutor adjusts the difficulty of a problem based on the student model. 1 Introduction One-on-onehuman tutoring is much more effective than traditional classroom instruction (Bloom, 1984). We are building systems with the goal of emulating techniques that human tutors use, which can result in comparable learning gains (Shute et al., 198...

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Navigation through large hypermedia information spaces is complex and is an important application area for adaptivehypermedia systems. User navigation can be best supported when the design of the hypermedia system is embedded in an evolutionary process model that takes into account the decentralization of data sources and the variety of users. The paper deals with distributed frameworks for open hypermedia systems# it focuses on the design work done to make adaptivean existing actor-based architecture for hypermedia. The approachfollows the initial design approach used in the definition of the hypermedia platform, that is the actor-based computational model. We present in detail the new actor classes and the cooperativeschemes which allow adaptation within the resulting architecture. 1

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In this paper the definitions of and approaches to user modeling in natural language dialog systems have been reviewed. The contents of user models are discussed; how user modeling in different research areas relates to user modeling are reviewed; examples of some techniques for building user models through natural language interaction and observed behavior in other media channels are given. Furthermore, the uses of user models in natural language dialog systems are discussed, as well as the implications of employing user models. It is concluded that natural language aspects of user modeling is needed to complement traditional user modeling in high-functionality applications.

Adapting explanations to users with varying background knowledge and abilities is a difficult task: the explanation content, style, amount of details, terms used, etc. may be affected in various ways. We have used our analysis of the information seeking tasks of the users in one particular domain as a basis for adaptation. We structured the domain information into a set of information entities where each entity describes one aspect of a node in the information space. Each information entity is fitted to one or several information seeking tasks, and by combining entities we create an explanation adapted to the user's current task. We do not avoid concepts which are unknown to the user in our information entities. Instead we allow the users to ask follow-up questions on those concepts in order to cater the users' differences in background knowledge. Which follow-up questions are available also depends on the users' current task. Finally, we emphasise the need to make the difference betwe...

The need exists in the work force for generic intelligent user interface agents to address the problem of increasing taskload that is overwhelming the human user. Interface agents could help alleviate user taskload by providing abstractions and intelligent assistance in a self-contained software agent that communicates with the user through the existing user interface and also adapts to user needs and behaviors. The benefits of a generic intelligent user interface agent environment is it can be applied to any highly interactive and information intensive software system from freight and parcel management systems to Wall Street financial investment and analysis. We desire to address the two following difficulties with developing interface agents: (1) The extensive number of existing computer systems makes it impractical to build these agents by hand for each system; (2) Any such agent must be compliant with existing user interface standards and business practices (e.g., the United States...