Human Factors and Human Error Analysis
This domain tests whether you can explain human error using a model, identify performance-shaping factors, and choose design changes over blame. Questions often describe a task failure and ask for the error type or the most effective corrective action.
Error types and context
Skill-based slips and lapses occur during routine action; rule-based mistakes occur when a known rule is misapplied; knowledge-based mistakes occur when the situation is unfamiliar. Violations are deliberate deviations from rules. Rasmussen’s skill-rule-knowledge framework helps classify demands. Performance-shaping factors include fatigue, workload, time pressure, training, interface quality, procedures, supervision, staffing, and environment. Latent conditions in design or organization often set up active failures.
Analysis methods
Task analysis and hierarchical task analysis break work into steps. Human HAZOP, HEART, THERP, and CREAM support error identification and quantification. Walkthroughs and simulators reveal interface problems that paper analysis misses. Design should prevent error where possible and tolerate it where prevention is impractical, with clear feedback, affordances, and unambiguous displays.
Worked example
A technician opens the wrong valve on a panel where two valves look identical. Calling this “carelessness” is weak. The error is a skill-based slip caused by poor discrimination. The strongest correction is to differentiate the controls physically or by location, add an interlock, and require independent verification. Retraining alone is weaker because the design still invites the same slip. Reasoning: predictable error should be designed out, not attributed to character.
Traps that cost marks
- Using “human error” as a root cause and stopping there.
- Choosing training as the default fix for a design-induced error.
- Ignoring fatigue, staffing, and workload as performance-shaping factors.
- Missing latent organizational conditions behind an active failure.