Context card
Task analysis: one task, three lenses
Is task analysis one method, or are technical, collaborative and cognitive task analysis different things?
The short answer
They are three lenses on the same task. ISO 9241-11:2018 defines a task as a set of activities undertaken to achieve a specific goal and notes that these activities can be physical, perceptual and cognitive. Hierarchical task analysis asks what has to be done and in which order, team task analysis asks how the work passes between people, and cognitive task analysis asks what people have to know, notice and decide.
For: Technical writers, information architects, usability and human factors specialists, training designers
Key points
- Hierarchical task analysis (HTA, Annett and Duncan 1967) breaks a goal into subgoals and operations linked by plans; it is the backbone of procedures.
- Team task analysis (TTA) looks at the parts of a task no one can do alone: handovers, shared decisions and the flow of work and information between roles.
- Cognitive task analysis (CTA) makes visible the knowledge, cues, judgments and decisions experts use — what cannot be observed.
- Labels such as "technical", "collaborative" and "personal" task analysis are informal names for these established methods.
- RACI matrices, work breakdown structures and Kanban boards can use the results of a task analysis, but they are planning tools, not task analyses.
- In PLC programming, a "task" is a different concept: the execution unit of a controller.
The context
Same task, different questions
Task analysis studies how people achieve goals with a product or system. ISO 9241-11:2018 defines a task as a set of activities undertaken to achieve a specific goal; the activities can be physical, perceptual and cognitive. That is why the methods below are not alternatives: each describes another side of the same work, and a documentation project chooses the lens its readers' tasks need.
| Lens | Established method | Question | Typical output |
|---|---|---|---|
| Steps and plans | Hierarchical task analysis (HTA) | What has to be done, in which order, under which conditions? | Goal hierarchy with plans; procedures, preconditions, results |
| People and handovers | Team task analysis (TTA) | Which parts cannot be done by one person, and how does work pass between roles? | Role and handover map; responsibilities, communication points |
| Thinking | Cognitive task analysis (CTA) | What do people need to know, notice and decide? | Cues, decision points, typical errors, expert strategies |
Where the methods come from
HTA goes back to John Annett and Keith Duncan (1967): a goal is broken down into subgoals linked by plans that say when each subgoal is triggered, and the analysis stops where further detail no longer pays off. Team task analysis was developed in team training research (Baker, Salas and Cannon-Bowers 1998; Arthur and colleagues 2005, with "team relatedness" and "team workflow"). Cognitive task analysis is summarised in Working Minds by Beth Crandall, Gary Klein and Robert Hoffman (2006), for example with the Critical Decision Method.
One example, three lenses
Take the restart of a packaging line after a zone stop, as on the EPPO page Restart after a zone stop. HTA gives the steps: clear the cause, close the guard, reset, restart the zone in the right order. TTA shows the handover: the operator who reports, the maintenance technician who clears the jam, and who confirms that nobody is inside the zone. CTA shows what the operator has to recognise before the reset — a jammed carton that will block the next station, or a reset that only works locally. Procedures such as DITA tasks carry the HTA result; the other two lenses decide the warnings, notes and role assignments around it.
What task analysis is not
A RACI matrix or a work breakdown structure assigns and plans work; it can use the results of a team task analysis but does not analyse the task. Task allocation between people and machines is a design decision based on such analyses. And task analysis finds where human error is likely; it does not prove that a design or a document is safe.
Questions readers ask next
- Which lens does a technical writer need?
- Usually HTA for the procedures, plus the cognitive lens for decision points and warnings and the team lens wherever a task changes hands between roles.
- Is "personal task analysis" an established term?
- No. The established name for analysing the mental side of a task is cognitive task analysis (CTA).
- Is a RACI matrix a task analysis?
- No. It records who is responsible, accountable, consulted and informed. A team task analysis can provide the input for it.
Sources
- ISO 9241-11:2018 Ergonomics of human-system interaction – Part 11: Usability: Definitions and concepts (sample) — ISO, 1 March 2018
- Hierarchical task analysis: Developments, applications and extensions (N. A. Stanton) — University of Southampton, 1 January 2006
- Working Minds: A Practitioner’s Guide to Cognitive Task Analysis (Crandall, Klein, Hoffman) — MIT Press, 7 July 2006
- Team Task Analysis: Identifying Tasks and Jobs That Are Team Based (Arthur et al.) — Human Factors, 1 September 2005
Review log and changes
Every context card is checked against its sources before it is published, and again whenever it changes; the date under the byline is the last review. Corrections (something was wrong) and additions (something was missing) are logged below with date and time (Berlin time). Typos, formatting and link fixes are not listed.
Reviewed
No corrections or additions since publication.