VTechWorks staff will be away for the Thanksgiving holiday beginning at noon on Wednesday, November 27, through Friday, November 29. We will resume normal operations on Monday, December 2. Thank you for your patience.

Browsing by Author "Kies, Jonathan K."

Now showing 1 - 2 of 2
  • Thumbnail Image
    The effects of system response time and cognitive loading on accessing an automated telephone emergency service: examining elderly and young users
    Kies, Jonathan K. (Virginia Tech, 1994-11-15)
    The user interface for a proposed alternative emergency service was conceived and designed for a standard touch-tone telephone. The service would allow a user to activate an automated, pre-recorded message containing information to aid emergency responders. The user must only press a few specified keys on the telephone key-pad, avoiding the need for verbal interaction with a dispatcher. The interface was designed in terms of providing the necessary instructions for activation and considering various input strategies and feedback. Icons, written instructions, and voice feedback were employed in the development of a successful and effective interface between the user and the system. Because the system is expected to attract elderly users and families with young children, the performance and attitudes of these two age groups in regard to a system prototype were examined to determine if the interface was suitable. A two and eight second initial system response time were imposed upon users to determine any effect these delays might have on user response time, error rate, and subjective attitudes. Additionally, a secondary task, designed to increase cognitive loading was employed to determine if the system is usable while the user is engaged in a dual-task environment. The dependent variables used to gauge the effects of the manipulated variables include the objective measures of user response time and error rate and subjective questionnaire responses. The results of the study indicate that the elderly adults and young children were able to activate the system successfully. System response time and cognitive loading had no significant effect on user performance or subjective attitudes. Distinct practice effects were observed. Attitude scales indicated satisfaction with the service and its interface. Finally, a significant effect of age was observed on average user response time, with the elderly activating the system quicker than the children.
  • Thumbnail Image
    Empirical Methods for Evaluating Video-Mediated Collaborative Work
    Kies, Jonathan K. (Virginia Tech, 1997-03-18)
    Advancements in computer technology are making video conferencing a viable communication medium for desktop computers. These same advancements are changing the structure and means by which information workers conduct business. From a human factors perspective, however, the study of new communication technologies and their relationships with end users presents a challenging research domain. This study employed two diverse research approaches to the problem of reduced video frame rate in desktop video conferencing. In the first study, a psychophysical method was used to evaluate video image quality as a function of frame rate for a series of different scenes. Scenes varied in terms of level of detail, velocity of panning, and content. Results indicate that for most scenes, differences in frame rate become less detectable above approximately 10 frames per second (fps), suggesting a curvilinear relationship between image quality and frame rate. For a traditional conferencing scene, however, a linear increase in frame rate produced a linear improvement in perceived image quality. High detail scenes were perceived to be of lower quality than the low detail scenes, while panning velocity had no effect. In the second study, a collection of research methods known as ethnography was used to examine long-term use of desktop video by collaborators in a real work situation. Participants from a graduate course met each week for seven weeks and worked on a class project under one of four communication conditions: face-to-face, 1 fps, 10 fps, and 25 fps. Dependent measures included interviews, questionnaires, interaction analysis measures, and ethnomethodology. Recommendations are made regarding the utility and expense of each method with respect to uncovering human factors issues in video-mediated collaboration. It is believed that this research has filled a significant gap in the human factors literature of advanced telecommunications and research methodology.