Abstract: One of the main objectives of the AVANTI project is to extend the scope of current research on adaptability and adaptivity, in that the needs of disabled and elderly users are also taken into account. Existing user modeling tools can be fruitfully employed in this endeavor.
Research on adaptable and adaptive interactive software systems aims at rendering these systems tailorable to the needs of different user groups. Those end-user groups who have been considered so far were nearly always comprised of users with "average" physical and cognitive abilities. People with special needs (including disabled people, and to some extent also elderly people) should, however, also be given the opportunity to access computers, since they are indispensable at many workplaces and increasingly are becoming a medium through which important services at home and in public places can be accessed. For many categories of disabled people, computers may even allow for (partial) compensation of their handicaps.
Computer access for the handicapped has been a research issue for many years. Considerable effort has been put into making software systems accessible by user categories other than the ones they were -originally- designed for (e.g. for visually or motor impaired users) and into developing databases with information for disabled people that supplements already available data (e.g. information on wheelchair accessibility of public transportation, or verbal descriptions of paintings in major museums). These solutions mostly address a small number of disabled users and are, therefore, usually fairly expensive due to the restricted customer base. It seems, however, that techniques from the area of adaptable and adaptive interactive systems can be extended in such a way that they permit tailoring generic interactive software systems to all users, including the disabled and the elderly. This approach is not only theoretically more satisfactory, but may also be economically more viable than isolated dedicated solutions.
These different users have varying needs with respect to information content as well as information presentation. For example, information for lay-persons should not be very technical and detailed but instead be augmented by explanations and by visual material . Information for motor-impaired users should be supplemented, e.g., by data on wheelchair accessibility. Information for blind users should be complemented by data on services available for blind users. Moreover, such material cannot be presented visually, but only acoustically or via special output devices for the blind.
The selection of options and the preference of alternatives over the default is controlled by the user. If permitted by him or her, the system can, in most cases, choose options and pre-select alternatives automatically (either can be overridden by the user). The selections are made based on a central user model. Information about users is gathered with initial interviews and by monitoring users' interaction with the system. Pending results on user acceptability, smart cards will also be considered as an input device. Secondary information is derived with inference rules and stereotypes. Methodologies and tools for developing a user modeling server  and for producing adaptable and adaptive interfaces [7, 9] are being employed in the project.
The iterative evaluation of the AVANTI prototype is now nearing its completion. In particular, adaptability and adaptivity in the user interface and the information content levels are the subject of a separate, specifically designed part of the evaluation procedure, which is currently under way .
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 C. Stephanidis, Y. Mitsopoulos (1995): INTERACT: An Interface Builder Facilitating Access to Users with Disabilities. Proc. HCI International '95, Tokyo, Vol. 2, 923-928.
 C. Stephanidis, A. Paramythis, M. Sfyrakis, A. Stergiou, N. Maou, A. Leventis, G. Paparoulis, C. Karagianidis (1998): "Adaptable and Adaptive User Interfaces for Disabled Users in AVANTI Project", 5th International Conference on Intelligence in Services and Networks (IS&N '98), "Technology for Ubiquituous Telecom Services", Antwerp, Belgium.
 Stephanidis, C., Savidis, A., & Akoumianakis, D. (1997). Unified interface development: Tools for constructing accessible and usable user interfaces: Tutorial No. 13 in HCI International í97 Conference. Available at: http://www.ics.forth.gr/proj/at-hci/html/ publications.html
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