Human Error
Title: Human Error
Author: James Reason
Paperback: 316 pages
Publisher: Cambridge University Press (October 26, 1990)
Language: English
ISBN: 052131419
Author: James Reason
Paperback: 316 pages
Publisher: Cambridge University Press (October 26, 1990)
Language: English
ISBN: 052131419
Overview
This book is very academic, but does have useful information about the reasons people make mistakes and how to categorize them. This kind of information is crucial for understanding how to make software more survivable “in the wild.” To understand the following tables and diagrams, you need to understand a little about GEMS, the Generic Error-Modeling System. Reason separates errors into three categories:
- Skill-Based Errors (SB)
- Rule-Based Errors (RB)
- Knowledge-Based Errors (KB)
Distinctions between error types2
| DIMENSION | SKILL-BASED (SB) ERRORS | RULE-BASED (RB) ERRORS | KNOWLEDGE-BASED (KB) ERRORS |
| TYPE OF ACTIVITY | Routine actions | Problem-solving activities |
|
| FOCUS OF ATTENTION | On something other than the task in hand |
Directed at problem-related issues |
|
| CONTROL MODE | Mainly by automatic processors |
Limited, conscious processes | |
| PREDICTABILITY OF ERROR TYPES |
Largely predictable “strong-but-wrong” errors |
Variable | |
| RATIO OF ERROR TO OPPORTUNITY FOR ERROR |
Though absolute numbers may be high, these constitute a small proportion of the total number of opportunities for error |
Absolute numbers small, but opportunity ratio high |
|
| INFLUENCE OF SITUATIONAL FACTORS |
Low to moderate; intrinsic factors (frequency of prior use) likely to exert the dominant influence |
Extrinsic factors likely to dominate |
|
| EASE OF DETECTION | Detection usually fairly rapid and effective |
Difficult, and often only achieved through external intervention |
|
| RELATIONSHIP TO CHANGE | Knowledge of change not assessed at proper time |
When and how anticipated change will occur unknown |
Changes not prepared for or anticipated |
The dynamics of the generic error-modeling system (GEMS)3
Failure modes at each performance level4
Skill-Based (SB) Performance
| Inattention | Overattention |
| Double-capture slips | Omissions |
| Omissions following interruptions | Repetitions |
| Reduced intentionality | Reversals |
| Perceptual confusions | |
| Interference errors |
Rule-Based (RB) Performance
| Misapplication of good rules |
Application of bad rules |
| First exceptions | Encoding deficiencies |
| Countersigns and nonsigns | Action deficiencies |
| Informational overload | Wrong rules |
| Rule strength | Inelegant rules |
| General rules | Inadvisable rules |
| Redundancy | |
| Rigidity |
Knowledge-Based (KB) Performance
| Selectivity |
| Workspace limitations |
| Out of sight out of mind |
| Confirmation bias |
| Overconfidence |
| Biased reviewing |
| Illusory correlation |
| Halo effects |
| Problems with causality |
| Problems with complexity |
| Problems with delayed feed-back |
| Insufficient consideration of processes in time |
| Difficulties with exponential developments |
| Thinking in causal series not causal nets |
| Thematic vagabonding |
| Encysting |
Footnotes
1 All footnotes and quotations that are not otherwise attributed are from:
Human Error, James Reason, Cambridge University Press, New York, 1990
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+Bob Hays
- I'm a father and husband, have two schipperkes, like to read, compose music, travel. And I manage a couple software development teams at DIRECTV.
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September 11th, 2005 by alephnaught