6 Processes Underlying Human Performance

Two decades ago, a chapter on aviation with this title might have focused on physical aspects of human performance, on representing the control processes involved in flying. There has been such a fundamental change in our knowledge and techniques that this chapter focuses almost exclusively on cognitive processes. The main aims are to show that relatively few general principles underlie the huge amount of information relevant to interface design, and that context is a key concept in understanding human behavior. Classical interface human factors/ergonomics consists of a collection of useful but mainly disparate facts and a simple model of the cognitive processes underlying behavior— that these processes consist of independent information–decision–action or if–then units. (The combined term human factors/ergonomics is used, shortened to HF/E, because these terms have different shades of meaning in different countries. Cognitive processing is the unobservable processing between arrival of stimuli at the senses and initiating an action.) Classic HF/E tools are powerful aids for interface design, but they make an inadequate basis for designing to support complex tasks. Pilots and air traffic controllers are highly trained and able people. Their behavior is organized and goal-directed, and they add knowledge to th