Navigation 2 Map Windows 3 The Two Navigational Techniques Studied 4 Objectives 4 Map Window 5 Zoom Navigational Technique 5 Roam Navigational Technique 5 Experiment 6 Results of Task

Often the components of a problem can be arrayed on a two-dimensional information space (e.g., abstract tree or Hypertext) far too large to fit onto the display screen of a workstation. With current navigation techniques it is often difficult for users to keep track of their location or to move rapidly to remote locations in the space. We developed two similar direct-manipulation techniques that both use a mapwindow--a miniature of the entire information space--with a wire-frame box to aid users in remembering their location. The first technique allows the user to rapidly "roam"' over the information space by moving the location of the wire-frame box. The second allow for 'zooming" as well as roaming. A controlled experiment compared the above techniques to scroll bars for determining whether a target word was in a large balanced binary tree of words. The experiment also examined the merit of the map window. Map windows significantly improved user performance, and the roam and zoom techniques were significantly faster than the scroll bars. Our observation of subjects and their verbal protocol indicated that a paging feature on the scroll bars--allowing rapid movement of the screen a page in any direction--was advantageous.