EXAMINING THE EFFECTS OF ICON CHARACTERISTICS ON ICON MENU SEARCH PERFORMANCE
The use of icons is ubiquitous in the computing world of today with icon selection being a typical way to access documents and programs. Icons are used in a variety of ways: search, identification, and selection (mouse, touchpad, etc.). Users search for and identify icons on modern computing devices in order to select the appropriate one. Before being able to identify a new icon or recognize a previously used one, users must engage in a visual search of the interface to pinpoint the icon they wish to use. The icon search action is therefore inherently important since it kicks off each and every icon selection made. For this reason this dissertation focuses on the search aspect of icon usage.Taking the time to examine how icon design characteristics contribute to icon usability behooves both icon and icon interface designers. Researchers have identified a handful of icon characteristics to predict icon usability. Important characteristics used in prior research using antiquated icon sets include visual complexity, and to a lesser extent concreteness, familiarity, and aesthetic appeal. These characteristics affect performance in searching for and locating icons. Small time savings in icon search tasks add up quickly and contribute to smooth user experience. The user's level of satisfaction increases when their interactions are swift and they experience the user interface as easy to use. This dissertation examines the effects of icon characteristics on visual search efficacy by employing a commonly used search task and by including mobile application icons in the stimulus sets. Icons were selected from the Google Play Store and from Apple’s App Store for search experimentation varying orthogonally on icon characteristics across visual complexity, concreteness, and aesthetic appeal. An initial, pilot study employing a naturally occurring set of modern, mobile application icons revealed a joint interaction of complexity and appeal. Previous studies found icon appeal to quicken search only when the icon was already difficult to find, such as when the icon was complex. The pilot study found that appeal quickened search when the icon was simple. Although this finding was not exactly similar to prior work, the appearance of a join interaction between appeal and complexity was remarkable. To better balance the icon characteristics across the stimulus set all follow up studies used subsets of icons that were selected to be as uncorrelated on the three icon characteristics as possible. Unfortunately, efforts in balancing icon characteristics across groups for all three icon characteristics proved challenging, and so visual complexity and appeal were properly varied across four experimental groups for the more in-depth experiments.All experiments, including the initial pilot studies, revealed that visual complexity was the main determinant of icon search time. Given that the icon stimulus set was derived from a mixture of several different icon sets, the variety and therefore the range of appeal across icons in the final stimulus set was greater than that of stimulus sets used in previous work. By including mobile application icons in the experiments, this dissertation makes ecologically valid design recommendations according to design characteristics of visual complexity and aesthetic appeal in modern application icon design. Lastly, the diversified stimulus set of icons used in the main experiments is included for future researchers interested in icon search. The normed characteristic ratings on the Diversified Icon Stimulus set used in experimentation here provides a starting point for further investigation of icon search and of the user experience involved in icon search in general.