Errors: An Inherent Part of Human-System Performance - Foundations for Designing User-Centered Systems - page 276

Chapter 10
Errors: An Inherent Part
of Human-System Performance
Abstract In this chapter we consider how errors contribute to accidents, large and
small, and what we can do about them. We discuss the problem of post-hoc
analyses, the types of human error that can occur, and how to design systems in
such a way that the errors can be appropriately managed. The examples illustrate
how user's characteristics in terms of psycho-physiology, fatigue, cognitive pro-
cessing, and social situations can all contribute to failures. We especially note the
importance of Norman's (and others') main guideline about needing to design for
error.
10.1 Introduction to Errors
In this chapter we provide an introduction to the topic of what is often called
human error. As Reason ( 1990 ) notes, ''human error is a very large subject, quite
as extensive as that covered by the term human performance,'' so we can only
really provide a selective overview of some of the major issues.
We have deliberately separated the discussion of errors into a separate chapter.
This is because errors are an inherent part of system performance. In other words,
they often arise as a combination of factors at the anthropomorphic, behavioral,
cognitive, and social levels in the ABCS framework. If you look again at the
example of the Kegworth air accident (see the Appendix), you should be able to
appreciate this more fully at this point in the topic.
Our purpose here is to highlight the need to think about your users in context,
and to determine what kinds of factors can give rise to erroneous performance. By
highlighting the relationship between system performance and error, we hope to
show you why it is important to think about designing for error (Norman 1988 ,
2013 ). One way of designing for error is to identify the situations that can lead to
erroneous performance, and then put in place appropriate mechanisms to either
prevent the errors, or at least mitigate the adverse consequences arising from those
errors.