A user model is created with the help of this information and this model is in turn used as a basis for establishing the user interface adaptation. Task models have also been used for designing adaptive hypermedia. Different types of computer users can be associated with different task models. Task models are used to depict the activities that are to be performed from the user's point-of-view. (Jacko; Sears, 518) Adaptive navigation support for hypermedia systems has also been explored as a means of personalizing or adapting user interface. Several prototypes have also been developed to show the way different navigational possibilities can be presented on the basis of user models. In recent times, research has concentrated on the mechanism of abstractions of objects to produce "operationally reliable software infrastructures" that provide alternative physical realizations. Development of systems like JavaBeans by SunSoft and ActiveX by Microsoft representing componentized technology shows the efforts undertaken by the mainstream division of the it industry to offer technological structures to provide accessibility support and more adaptive interfaces. (Jacko; Sears, 520) Another recent development in this field has been the development of the AVANTI system -- a "single unified user interface" which employs a rule-based adaptivity technique called and has been designed for disabled users. (Aykin, 207)

Adaptive graphical interfaces have a broad range of applications in a wide variety of fields. The field of medical information is one such domain where adaptive graphical interfaces through hypermedia navigation can be made possible. Hypermedia navigation permits relevant information to be directly accessed and the disposal and data presentation mode can be adapted based on the user needs. A clinical workstation prototype, called HEMA -- Health data Manager Application has been proposed by French researchers. The interface provided by this prototype is able to take psychological behavior and cognitive characteristics of each user into account. This prototype can capture and implement a user's manner of working as well as his or her knowledge. The navigational links in this proposed hypermedia application contains both generic and specific links. Generic links are inbuilt into the system based on the knowledge gathered by domain experts and help to create pertinent links which can be instantiated by the system itself during consultation of patient records. On the other hand, specific links can be set up by the user while consulting patient records and can be established to create a new relationship between two areas of information. (Patel; Rogers; Haux, 132)

Another design of an adaptive graphical interface has been put forward by Igarashi et al. For teleoperation system. Teleoperation systems require a fine balance of human abilities as well as computer processing. An adaptive GUI that presents appropriate displays to increase an operator's efficiency and reduce errors by adapting to his/her level of knowledge/cognition would be a significant advancement in this field. In teleoperation, communicational constraints result in a less than adequate supply of feedback information with regard to quantity and quality. (Igarashi; Takeya; Kubo; Suzuki; Harashima; Kakikura; Industrial Electronics Society, 6)

Another problem is that the cognition capabilities of humans and the display functions of the user interfaces possess many limitations even though it is expected that the human operators comprehend a significant portion of the feedback information. On the other hand, it is also a fact that the ability of human beings to create a global plan in response to a potential problem contributes to intelligent operations and a degree of flexibility that no autonomous robots can accomplish. This adaptive GUI design proposed an "effective alert function" based on the characteristics of human cognition which would reduce misrecognition on part of the human operator. These human cognition characteristics may vary based on the position and information emphasis media. Additionally, this design also measures the human sensitivities to the GUI so as to ensure an effective and alert adaptive user interface. (Igarashi; Takeya; Kubo; Suzuki; Harashima; Kakikura; Industrial Electronics Society, 6)

A significant challenge in the field of adaptive GUI development is the ability to create realistic adaptivity which actually enhances the human computer interaction and increases the usability of the system. Nothing can be gained from a costly adaptivity system which provides a minimal enhancement in usability. It would be of no use to create an adaptive interface in response to a user characteristic if that particular characteristic cannot be discreetly or reliably deduced from the system-user interaction. Wrong inferences may reduce the predictability of the system and the confidence of the users in the accuracy and functioning of the system may decrease. (Benyon, Accommodating...

In fact, flexibility and usability are inversely proportional to each other and one of the main challenges of designing an effective adaptive interface is to find the optimal combination of these two important system characteristics. Lack of consistency poses another problem with regard to usability. According to research carried out in the field of human computer interaction, it has been seen that user performance is supported by user interfaces that display consistency. On the other hand, the interactive nature of adaptive user interfaces leads to lack of consistency which may eventually lead to poor system performance. (Benyon, Accommodating Individual Differences through an Adaptive User Interface); (Karwowski, 988)
An adaptive graphical interface may be considered effective if the quality of the information provided by the system is high, accurate, and has an optimal performance time. In addition, its effectiveness also depends on the subjective evaluations of the users. There is a serious dearth of studies regarding the advantages of adaptive systems over non-adaptive ones and the evaluation of adaptive interfaces must deal with two particularly important problems. Firstly, the outcomes, both positive and negative of newly introduced adaptations to graphical user interfaces may not appear immediately but after extensive and more or less long-time use. Research work involving short-term observations or experiments may not provide the correct representation of the actual scenario. Secondly, adaptivity may result in dynamic changes in the properties or functionalities of the computer system which may have differential effects on various users. Some users may find some interface adaptations to be advantageous whereas others may find the same adaptations confusing and would find it better to have them switched off. If adaptive graphical user interfaces have to achieve success, then these potential variations in user reactions must be considered. (Benyon, Accommodating Individual Differences through an Adaptive User Interface); (Karwowski, 988)

An important point in the context of adaptive graphical interfaces is the use of culturally adaptive interfaces. There has not been much research in this area since the growth of Internet has led to most of the work being conducted in the adaptive hypermedia systems or web-dependent. As a result, studies in other areas have more or less stagnated. An adaptation to the user's cultural frame is not something that the global user is accustomed to and is more familiar with software that embeds the cultural values of the Western world. On the other hand, culturally adaptive interfaces may be distinctly helpful and may even increase the efficiency of the user. It may be possible to map specific cultural behavior onto a user interface model. This would require identification of universally applicable cultural markers that are valid across all user interfaces. (Aykin, 210)

Again, the usability factor must be thoroughly investigated in every case. In this context, it is important to remember that the average global user is not accustomed to having cultural adaptations made to his/her graphical interface and may initially feel uncomfortable and even reject the adaptations. Repeated and prolonged use may overcome user resistance and the advantages may finally outweigh the uneasiness of dealing with the new modifications. In these cases where adaptations are extremely important but infrequent, it is better to choose computer-supported adaptation, where control lies more with the user, over automatic adaptation. A useful addition to such an adaptive GUI would be to incorporate an easily accessible history log which tracks the recent adaptive changes which also permits the user to retract changes at any point of time. (Aykin, 210)

In recent times, there has been a proposal to develop adaptive and self-managed GUI using agent-based technology. Such an approach may become necessary since this technology allows an expansion or modification of the system to be anticipated and implemented during run-time. It also allows certain components of the GUI to have autonomous features. Such adaptive GUIs may possess various diverse or complex kinds of interaction between internal components along with interaction with heterogeneous resources that are externally distributed. This technology also has the advantage of providing fault tolerance. (Kernchen; Dumke, 40)

Having discussed a wide variety of technologies and techniques being pursued in the development of adaptive graphical interfaces, one can understand the significance of having adaptive mechanisms inbuilt into the system as well as providing some degree of control to the user. Another factor which has emerged from the discussion is the…