One basic feature of the existing mainstream WIMP (Windows, Icons, Menus, and Pointer) interfaces is that the user communicates with the computer system via a single stream of spatial input, physically driven by a 2 degree of freedom input device, typically a mouse, and graphically displayed as a cursor. The universal cursor travels around the entire interface, switching its functions from pointing, to selection, to drawing, to scrolling, to opening and to jumping, according to what virtual devices (widgets), such as the main document/window, a menu, a scrolling bar, an icon or a hyperlink, has been acquired and engaged. Such a single stream operation, needless to say, has offered the users many advantages such as the ease of understanding and learning the interaction mechanism. The disadvantage, however, is the limited communication bandwidth (Buxton 1986) and the physical (Buxton and Myers 1986) and cognitive (Leganchuk, Zhai and Buxton 1996) cost of switching between widgets and control points.
To overcome these problems, our research at the IBM Almaden Research Ccnter investigates various devices and techniques that provide multi-stream input, manipulated by either one or two hands. One of the several experimental studies we have conducted to date is multi-stream document (web) browsing.
One of the most frequent tasks in interacting with computers is browsing. A document, such as a text file, a spreadsheet, a folder, and most importantly, a WWW page, is often larger than the viewing window that competes for space with multiple other windows on the same limited computer screen. When working on such a document, the user's point of interest often moves to outside of the viewing window, forcing the user to move (scroll) the document.
In a task that involved both scrolling and pointing, we evaluated three multi-stream input methods against the current, standard mouse with a scroll bar technique. The results showed that a mouse with an finger wheel (the Microsoft IntelliMouse), did not improve user’s performance. Two other methods, namely a mouse with an isometric rate-control joystick operated by the same hand (Trackpoint Mouse) and a two handed system that put a mouse on the dominant hand and a joystick on the other (Trackpoint in keyboard + Mouse), both significantly improved users’ performance. Subjective preference were in agreement with the performance measures.