Recently, there are a lot of studies on eye-gaze input interfaces. Because the eye-gaze input interface enables users to operate PC by eye movements, even disabled persons with deficiency on the upper limb can easily interact with a computer. However, many problems remain to be overcome so that the eye-gaze input systems can be put into practical use. The scroll method that changes the scroll velocity nonlinearly as a function of scroll location has not yet been proposed. It has also not been explored how the scroll location on Web browsers affects the performance. Although a few scroll methods have been proposed, these are not assumed to be used on Web pages. In this study, an attempt was made to determine empirically the optimal one among the four types of scroll method (improved scroll-icon, auto-scroll and improved auto-scroll method (quadratic and quadratic combination)). As a result, it was found that the improved auto-scroll methods (quadratic and quadratic combination) with nonlinear relationship between the scroll location and the scroll velocity were optimal from the viewpoints of the task completion time, the error rate and the subjective evaluation on usability.

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For the efficient transfer of skills from expert workers to inexperienced ones, it is necessary to analyze their performance. In the present study, we evaluated the skills of workers at the process of glass forming, wherein the workers heat up a glass cylinder with fire and form glasses into different shapes. In the process, workers are required to rotate a glass cylinder over a gas burner for uniformly heating up the glass. Three workers with different skill levels performed two different tasks —stretching a glass cylinder and expanding the end of a glass cylinder into a funnel shape— were monitored using video cameras and an infrared thermograph. These workers also performed the task of rotating a glass cylinder, in which five inexperienced workers also participated in. Results indicate that, by stably rotating the glass cylinder, an expert worker can increase the production rate and the quality of the products. Moreover, the stability of rotation showed a positive correlation with the stability of finger movements of the worker. A further analysis of the finger movements suggests that dexterity and a unique way of holding the glass cylinder enables the expert worker to smoothly and stably rotate the glass cylinder.

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