Alternative Computer Access PDF Download

Current access technology for people with disabilities is based on a concept called transparency. Developers have generally interpreted this by building access systems that emulate the keyboard and mouse. In contrast, this thesis proposes and studies a refinement to transparent access, called task transparency. This approach has much potential impact on scanning access within a GUI. Here, scanning is applied to the underlying tasks, rather than emulating the input devices. The goal is to derive new knowledge and understanding of the interactions that arise with a number of strategies that apply switch-based scanning to text selection in a task transparent fashion. In the case of selecting text, it was demonstrated that directness to the task could be achieved with minimal effort by applying scanning within the text area itself. The concepts are readily extended across other GUI objects including menus, buttons, and window controls. These objects can be incorporated within the access system such that they are directly engaged in the scanning. Through such strategies, users can significantly reduce their efforts and in doing so achieve greater overall productivity, and accomplish tasks that are otherwise strenuous. Text scanning was implemented using repeating keys injected by an on-screen keyboard such that the user perceived scanning in the text area. Two test applications were developed and used to evaluate a number of proposed text scanning strategies. In addition, predictive performance models were derived to predict performance measures under error-free conditions. Initial design guidelines for scanning in a task transparent fashion were also formulated. An access system developer could extend the concepts in new ways with scanning and other access methods. Future areas of research are identified that may improve overall productivity. Through this work I have contributed new knowledge towards improving scanning access and I have demonstrated the feasibility of task transparency by which further gains are possible.