Human Factors of Functionality and Intelligent Avionics
John M. Hammer Hammer & Associates, Norcross, GA
The usability of systems is determined by interface functionality and presentation. Much research in human factors has concentrated primarily on presentation--the surface aspects of the interface. Today, interface presentation and interaction have greatly improved to the extent that navigating the interface is much easier. Understanding the functionality of the interface from its presentation can still be quite difficult, and this functionality has a significant impact on usability. This problem is termed the human factors of functionality. It complements the area of mental models, which studies how users adapt and understand system functionality ( Kieras, 1990; Rouse, Salas, & Cannon-Bowers, 1992). This chapter deals predominantly with how system functionality should be designed to adapt to users.
How does functionality influence usability? First, the functionality partly determines the tasks that the user performs and, in some cases, how these tasks are performed. The functions require inputs, and there are a variety of ways that inputs can be organized conceptually. The concepts presented determine in part how the user thinks about the interface. For example, the degree of control level automation determines whether the user is continuously involved in the task or only intermittently involved. The amount of sensing available and the information integration determine whether the user must gather information from one subsystem source and enter it into another subsystem. The degree to which the system understands its own functions, their applicability, and the user's goals can have a potentially tremendous impact on the usability of functions ( Hammer & Small, 1995; Rouse, Geddes, & Curry, 1987; Rouse, Geddes, & Hammer, 1990).
This chapter argues that a system that understands itself and the user is the next revolutionary step in avionics architecture. It covers some human factors problems in avionics functionality and describes a revolutionary avionics architecture that we feel can address these problems.