Today the effective use of computers (e.g. those with Internet browsers and graphical interfaces) involves the use of some sort of cursor control like what a mouse provides. However, a standard mouse is not always the best option for all users. There are currently many devices available to provide alternative computer access. These devices may be divided into categories: brain-computer interfaces (BCI), mouth-based controls, camera-based controls, and head-tilt controls. There is no single solution as each device and application has to be tailored to each user's unique preferences and abilities. Furthermore, each device category has certain strengths and weaknesses that need to be considered when making an effective match between a user and a device. One problem that remains is that these alternative input devices do not perform as well when compared to standard mouse devices. To help with this, assistive user interface techniques can be employed. While research shows that these techniques help, most require that modifications be made to the user interfaces or that a user's intended target be known beforehand by the host computer. In this research, a novel target-agnostic assistive user interface algorithm intended to improve usage performance for both head-operated and standard mouse devices is designed, implemented (as a mouse device driver and in host computer software) and experimentally evaluated. In addition, a new wireless head-operated input device requiring no special host computer hardware, is designed, built and evaluated. It was found that the Virtual Dynamic Tunnel algorithm improved performance for a standard mouse in straight tunnel trials and that nearly 60% of users would be willing to use the head-tilt mouse as a hands-free option for cursor control.

Computer usage today is predominantly based on graphical interaction, where the visual presentation of information is essential both for input (hand-eye coordination when using a computer mouse), and output (seeing the information on a computer screen). This can create difficulties for blind computer users, both at an individual level when interacting with a computer, and also when collaborating with other computer users. The work presented in this thesis has investigated interaction for blind computer users in three stages. First investigating access to information by making studies on an interactive audio-only game, drawing conclusions about auditory direct manipulation and auditory interface design. Second studying collaboration between blind and sighted computer users in two different contexts, leading to questioning of commonly expressed design principles regarding access to collaboration. Finally studying accessibility in a working environment, finding out how technology, the assistive device used by the blind person, communication with others and professional knowledge interplayed to create an accessible work environment. Based on these empirical studies, the main conclusion from this work is a proposal of a research perspective, Assistive interfaces as cooperative interfaces. Here, the context where the interface is going to be used is in focus, and cooperative and social dimensions of interaction are acknowledged and highlighted. The design and analysis of assistive devices should be highly sensitive to the socio-interactional environment, and not just focusing on the single individual using an assistive device. / QC 20100921