Adaptive User Interface Design and Its Dependence on Structure D P Sanderson and S Treu presented by Senis Busayapongchai INTRODUCTION This paper presents view and approach to designing the adaptive component of an interface system named N-CHIME (NCR-sponsored Cohesive, HSL-oriented, Interactive Modeling Environment). HSL (Hierarchical Simulation Language) was designed to be used for interactive modeling and simulation of systems. Its application was expected to be used by non-experts in modeling and simulation methodology, such as salespersons, to illustrate potential system performance by carrying out dynamic modeling and simulation of selected system configuration by using a graphics editor and programmed in HSL respectively. The hardware and software platform was to be PC-based. N-CHIME is a supportive interface system that sits between the user and the HSL-based application domain. Its purposes are to 1. facilitate 2. provide context 3. not constrain the user in carrying out tasks of a system 4. adapt to individual user needs N-CHIME is designed to be depending on the structures of methodology, user, and system and their interactions. Structure dependency are significant for 1. users who need helps or directions to use the interface. 2. applications that are designed to enable the designer to perform item 1. ADAPTATION CONDITIONS The adaptation conditions explain the conditions that adaptation will take place. They help the designer to select and develop the desired structures. They could be obtained by asking the following questions 1. Why adapt? 2. Adapt to whom? 3. Where to adapt? 4. When to adapt? 5. How to adapt? 6. Adapt with what?
Purpose - Why adapt? For example, to enable users to complete tasks more quickly or with less knowledge and effort. For N-CHIME, they are previous mentioned in the introduction. However, a system may not need to adapt dynamically to the user. For example, expert users may need complete control of the system. Object - Adapt to whom? Usually the user of the system. The next step is then to analyze and develop a user model to be utilized in making adaptation decisions. Domain - Where? In which domain(s) does the adaptation take effect? Some of them are: 1. How the application works at the low or command level? 2. How the interface works in terms of functional capabilities? - may not depend on application 3. How the interface works in terms of helping a user at a high level interaction with the application? (N-CHIME focused on this item) The domain must also be structured to meet the following conditions 1. Locality: states in the user-domain interaction that changes should be made 2. Granularity: what level in the locality the changes should be made Timing Considerations - When? Examples: 1. when a user is in a particular domain 2. how well a user prepares to perform the task 3. how critical the application is Manner - Adapt how? These adaptation actions have to be clearly defined. Means and Methods - With what? Ways or forms of adaptation must be possible and useful. These changes may either be visible to the user or be kept for use later. They can be based on 1. Knowledge bases that represent each of the adaptation object, domain, and interface medium 2. Rule-based expert system that utilizes the knowledge bases to make changes according to defined conditions. In order to design such an adaptive system, supportive structures are needed to guide the designer and to represent required modules, conditions, criteria, and forms of adaptation. SUPPORTIVE STRUCTURES The categories of these supportive structures are 1. Structured Design Methodology 2. Structured Interaction between user and application 3. Structured Knowledge Representation 4. Interface Software Architecture The relation of each categories is represented in
. Structured Design Methodology This category discusses about the effects among adaptation PURPOSE, OBJECT, DOMAIN, MANNER, and INTERFACE MEDIUM. N- CHIME considered the OBJECT, MEDIUM, and DOMAIN as main modules involved in AUI design which was implemented as a three-prong approach in
. The designer will look individually at each prongs and consider the interactions between them. Prong 1 mentioned about the analysis of intended users and their needs. N- CHIME categorized the intended users into novices, apprentices, and experts. Prong 3 or the domain is then specified. N-CHIME domain is limited to high-level guidance, direction, and explanation of the interface. After MEANS and METHODS for implementing the adaptation are determined along with the adaptation MANNER, the INTERFACE MEDIUM (prong 3) must be developed. Structured Interaction This category discusses about the analysis of DOMAIN and OBJECT, both separately and in conjunction. The result of the analysis will be as follows: 1. Representational schemes that the user can recognize and can guide the user during the interaction with the AUI. N-CHIME called it the state scenario graph. This is a directed graph that consists of high-level states or nodes (H-nodes) and transitions (arc) between them. Each H-node provides context for low-level support nodes to handle the adaptation when the user is on that node. An example is in
. 2. Decisions based on DOMAIN, and TIMING on the adaptation MANNER at any point of interaction. Structured Knowledge Representation This category discusses about the expert system that is used for making and carrying out the adaptation decisions at any place of user interaction. For N-CHIME, it has the following properties: 1. Analytic: analyze an interaction to identify and classify the user. 2. Synthetic: construct the interaction advises based on individual user and situations. 3. Control Type: address problem of interpreting, predicting, repairing and monitoring system behavior 4. Productive: consist of production rules, working memory, and rule interpreter. The expert system must be embedded in the interface such that it must act on the user's behalf without the user necessarily being aware of its activities. To accomplish that, it must be very efficient. It also must handle multifaceted domain utilization. The expert system for N-CHIME is modeled in
. Steps in developing an expert system are to 1. define the problem - control user interaction by modifying interface dynamically. 2. identify the types of relevant knowledge - interface, application, user and what the user knows. 3. determine how to represent the knowledge - rules with subsets associated with interactive state. The components of N-CHIME knowledge representation scheme are 1. States - state scenario graph 2. Rules - to control adaptation and assistance features - conditions & actions 3. Models - N-CHIME, HSL, M&S, User The criteria considered in N-CHIME rules conditions include: 1. Position in user state scenario graph 2. Session goal, as stated at the beginning of the session 3. user's level of expertise 4. Command selection 5. Stated preferences 6. Past behavior in same high-level state 7. Frequency of use and time lapse since previous use of tools 8. Recent command history The actions considered by N-CHIME include: 1. Tailor the output in a certain way 2. Act on a stated preference 3. By-pass a choice point 4. Provide guidance/feedback supportive of a declared goal 5. Produce an explanation 6. Enable interaction modes 7. Update user model parameter 8. Accumulate evidence of user behavior Analysis of N-CHIME knowledge considers global visible features, such as windows, local visible features, such as supportive tools, logical features, such as how to display. HSL knowledge analysis is guided by user goals. Analysis of modeling and simulation methodology is directed toward expert system support of various user goals. Analysis of dynamic user model considers who is to be modeled, what is to be modeled, how the information is to be acquired and how the information is to be maintained. Interface Software Architecture The architecture must provide the INTERFACE MEDIUM capable of accommodating the adaptation MEANS and METHODS, within the structured interaction, in a way that will support adaptation performance as desired. With N-CHIME, the architecture is based on hierarchical nodes types which is then associated with widget classes. The associations are depicted in
. Its software module also adheres to good practices of user interface design such as modular design, separation of physical and logical devices, separation of interaction techniques from dialog control, and separation of dialog control from application software.