PROCEEDINGS of the HUMAN FACTORS SOCIETY-27th ANNUAL MEETING-I983 SEARCHING FOR ITEMS IN MENUS: THE EFFECTS OF ORGANIZATION AND TYPE OF TARGET

Methods of organizing menu structures have received considerable empirical attention. Studies have compared categorical and alphabetical organizations with conflicting results. This experiment examined the effects of these and other organization types on visual search performance with 64-item menus. The effect of target type was also assessed by comparing performance using explicit targets as stimuli with that obtained using target definitions. Categorical menu organization was found to be superior to an alphabetical ordering, particularly when definitions are provided as stimuli. The effects of menu organization on item selection should be considered in the design of the user-system interface. These effects have been examined using both learning tasks (Liebelt, McDonald, Stone, & Karat, 1982; McDonald, Stone, Liebelt, & Karat, 1982) and visual search tasks (Barnard, Morton, & Long, & Ottley, 1977; Miller, 1981; Card, 1982). In these studies menus organized alphabetically, categorically, and randomly have been compared. While little has been directly reported regarding the effects of other variables, the results suggest that performance on menu-based systems may be affected by the number of menu items, the familiarity of subjects with these items, and whether targets are explicitly or implicitly supplied. One question addressed in the current study was: How does menu organization affect performance when there are many menu items? Card (1982), using a visual search task, has shown that for menus of 18 items there is an advantage for an alphabetical menu organization over categorical and random orderings. Using a similar paradigm with 16-item menus, we found an advantage for a categorical organization over alphabetical and random orderings, although the effect was not reliable. In the current study menus containing 64 items were used in order to assess the effect of organization on large menu structures. Five types of menu Organization were examined in this study. All menus consisted of 64 items arranged in 4 columns of 16 items. In three of the organization types, each column contained a different category of items. Within columns, these items were arranged categorically (CC), alphabetically (CA) or randomly (CR) . In the Alphabetical (A) organization the 64 items were presented in alphabetical order while i n the Random (R) condition items were randomly assigned to columns and rows. A second motivation for this experiment was a question concerning the "ecological validity" of the studies reported to date. It is generally held that menu-based interfaces are most appropriate when recall is imperfect and the user must rely on item recognition. In both visual search and learning paradigms subjects have typically been provided with explicit targets. Thus, if a subject is to select DELETE from a menu of word-processing functions, the target DELETE is provided as a stimulus. More realistically, a new or occasional user of a. menu-based word-processing system may want to "throw away" an old document but not know the exact function name (e.g., REMOVE, ERASE, DELETE, KILL) to accomplish the ta.sk. This is probably also a frequent event for users of multiple systems which perform similar tasks. Reinforcing our concern about validity, Card (1982) and others have shown that differences in menu-access performance due to organization disappear with practice. Once users are familiar with the terms used in the system, an experimental paradigm which uses explicit targets seems appropriate. However, as users become familiar with the system, the effects of menu organization on performance are reduced or eliminated! Differences among organizations should be greater when the user is unfamiliar with the system and