The design and evaluation of transparent user interfaces, from theory to practice

grantor: University of TorontoThe central research issue addressed by this dissertation is how we can design systems where information on user interface tools is overlaid on the work product being developed with these tools. The interface tools typically appear in the display foreground while the data or work space being manipulated typically appear in the perceptual background. This represents a trade-off in focused foreground attention versus focused background attention. By better supporting human attention we hope to improve the fluency of work, where fluency is reflected in a more seamless integration between task goals, user interface tool manipulations to achieve these goals, and feedback from the data or work space being manipulated. This research specifically focuses on the design and evaluation of transparent user interface "layers" applied to graphical user interfaces. By allowing users to see through windows, menus, and tool palettes appearing in the perceptual foreground, an improved awareness of the underlying workspace and preservation of context are possible. However, transparent overlapping objects introduce visual interference which may degrade task performance, through reduced legibility. This dissertation explores a new interface technique (i.e., transparent layering) and, more importantly, undertakes a deeper investigation into the underlying issues that have implications for the design and use of this new technique. We have conducted a series of experiments, progressively more representative of the complex stimuli from real task domains. This enables us to systematically evaluate a variety of transparent user interfaces, while remaining confident of the applicability of the results to actual task contexts. We also describe prototypes and a case study evaluation of a working system using transparency based on our design parameters and experimental findings. Our findings indicate that similarity in both image color and in image content affect the levels of visual interference. Solid imagery in either the user interface tools (e.g., icons) or in the work space content (e.g., video, rendered models) are highly interference resistant and work well up to 75% transparent (i.e., 25% of foreground image and 75% of background content). Text and wire frame images (or line drawings) perform equally poorly but are highly usable up to 50% transparent, with no apparent performance penalty. Introducing contrasting outlining techniques improves the usability of transparent text menu interfaces up to 90% transparency. These results suggest that transparency is a usable and promising interface alternative. We suggest several methods of overcoming today's technical challenges in order to integrate transparency into existing applications.Ph.D