When a person observes an event, participates in an activity, or makes a decision, he or she forms a "mental model" of the event, activity, or decision. These mental models are a person's conceptual thoughts of the way objects work, events take place, or people behave. In general, people form these mental models to manage the many inputs they are constantly receiving, including their own thoughts and sensory experiences (sights, sounds, and physical sensations) as well as the thoughts and experiences of others. By developing mental models, people learn how to effectively use the multiple inputs.
One disadvantage of this tendency to manage thought processes is that mental models are often constructed from fragmentary evidence, with a poor understanding of what is happening and a tendency to assumes causes, mechanisms, and relationships even when there are none. People tend to create cause-and-effect relationships whenever two things happen in succession.
In addition, people may even eliminate useful input because of their mental models, then become surprised by a false assessment in an accident or error. Yet, from the point of view of the person actually making the false assessment, the assessment appears quite natural at the time. When an L-1011 lost all three engines because of low engine oil (see main article), the crew did not believe that such a condition was possible. Indeed, the chances that all three engines could fail, according to the captain, were "one in one million." Once people have an explanation--correct or incorrect--for otherwise discrepant or puzzling events, the discrepancy or puzzle no longer exists. As a result, people become complacent about the explanation, at least for a while, regardless of additional events that may occur.
Mistakes, especially when they involve misinterpreting the situation, are difficult to discover. This is because the interpretation appears reasonable at the time. Many accident sequences or maintenance errors occur because the participants "explain away" the anomalous information, evidence, or circumstances that they later understand caused the error.
return to top | Boeing Home | Commercial
Copyright © The Boeing Company. All rights reserved.