Human Factors & Ergonomics — Disciplines, Methods & Applications

Human factors and ergonomics apply science to fit systems to people. Depending on the product and context—costs, safety, user interface, tasks, and legacy expectations—different sub-disciplines are combined to reach a usable, safe, and efficient design.

When and why to apply HF/E

• Product requirements: manufacturing costs, marketing goals, safety and regulatory constraints.
• User–product interface: handheld, seated/standing use, mobile vs. fixed, environmental constraints.
• Applications & tasks: task complexity, feedback needs, training burden, error tolerance.
• Legacy & expectations: prior models, user habits, industry conventions, migration paths.

Rule of thumb: Combine 2–3 relevant disciplines for each major design decision; iterate as fidelity and evidence increase.

Core disciplines

1) Human–Machine Interface (HMI) layout

Assesses whether the layout of controls and displays (buttons, screens, handles, seats, etc.) supports tasks, priorities, and risk controls.

• Outputs: control–display mapping, grouping by frequency/criticality, labeling, coding (shape/size/color), placement rules.
• Inputs: task analysis, use scenarios, environmental constraints, safety requirements.

1a) Reach envelope analysis

Verifies that the target user population can reach and operate components within posture and clearance limits.

• Dataset & coverage: representative anthropometry; often design for 3rd–97th or 5th–95th percentile depending on risk.
• Methods: digital human models, mock-ups, on-body measurements; confirm with formative tests.

1b) Visibility / view analysis

Ensures the user can see displays, indicators, and hazards in expected postures and conditions.

• Consider: eye/neck limits, obstructions from body/structure, glare, luminance/contrast, symbol legibility.
• Methods: DHM/line-of-sight tools, visual cones, viewing task maps; confirm with user trials.

2) Workload analysis

Evaluates task order, complexity, and cognitive load to reduce error risk and optimize performance.

• Techniques: scenario-based observation, time-on-task, error logging, subjective ratings (e.g., NASA-TLX), think-aloud.
• Outcomes: display/control re-prioritization, automation aids, training cues, procedural changes.

3) Human error analysis

Identifies error opportunities (slips, lapses, mistakes, violations) and designs mitigations.

• Approach: test with less-experienced users first to reveal ambiguity; apply clear labels/symbols, affordances, interlocks, confirmation steps.
• Deliverables: error list, risk ranking, mitigations, residual-risk documentation.

4) Task & task-profile analysis

Builds the conceptual backbone: task flows, action–object mappings, states, and transitions used by other HF/E studies.

• Outputs: user goals, preconditions, success criteria, exception paths; candidate acceptance criteria.

5) Predetermined time standards

Estimates process times and analyzes time–motion efficiency to improve throughput.

• Examples: Work-Factor, MTM/Mento-Factor; requires well-defined task models and observation.

6) Cognitive task analysis (CTA)

Surfaces the knowledge, strategies, and decision cues required in realistic, variable, or stressful contexts.

• Notes: high effort/cost; valuable for complex domains (aviation, healthcare, control rooms).

7) Critical decision analysis

Interview-based method with expert users to extract decision points, cues, and pitfalls for high-stakes tasks.

• Tip: use experienced facilitators; triangulate with observation data.

Typical process & deliverables

1. Define users & context: personas, environments, constraints.
2. Map tasks: task profiles, scenarios, critical paths.
3. Model fit & view: reach envelopes, visibility maps, clearances (see Anthropometry).
4. Prototype & test: formative evaluations; capture errors, workload, and usability issues.
5. Iterate & mitigate: apply design changes; re-test.
6. Document: requirements, rationales, datasets, acceptance criteria, and residual risks.

Typical deliverables: user profiles, task flows, HMI layout rules, reach/visibility maps, workload and error findings, mitigations, and test reports that tie back to acceptance criteria.

References

• Pheasant, S., Haslegrave, C. M. (2006). Bodyspace: Anthropometry, Ergonomics and the Design of Work (3rd ed.), CRC Press.
• MIL-STD-46855, Human Engineering Requirements for Military Systems, Equipment, and Facilities (2011).
• MIL-HDBK-759, Human Engineering Design Guidelines (2012).
• MIL-STD-1472, Human Engineering (2012).
• MIL-HDBK-1908, Definitions of Human Factors Terms (1999).

Related: Ergonomics — Definition · Anthropometry — Definition · Tools & Simulation Standards . Ergonomics Case Study