The HCD Iterative Process
Four activities, iterated repeatedly (the "spiral method"), each cycle yielding more insight. Runs inside the The Double-Diamond Model of Design (used in both the find-problem and find-solution phases).
1. Observation
- Design research about the people who will use the product (not lab science).
- Applied ethnography: observe would-be users in their natural environment (home, work, commute). Faster than academic anthropology because schedule/budget-driven.
- Study the activity, not just demographics — activities are similar across cultures (see Activity-Centered Design); study the exact subculture only when the product targets one.
- Go to the actual country/users; don't shortcut with stand-ins at home.
2. Idea generation (ideation)
- Generate numerous ideas — don't fixate early.
- Be creative without regard for constraints — don't criticize ideas (even crazy ones hold insights).
- Norman's third rule: question everything, especially "stupid" (fundamental) questions.
3. Prototyping
- Build quick, cheap mock-ups: sketches, foam/cardboard, slides, index cards, skits.
- Wizard of Oz method: simulate a powerful system with a hidden human (Norman's airline-reservation study revealed users needed problem-solving, not just language parsing).
4. Testing
- Test people matching the target population, in realistic use.
- Even for single-user products, test pairs (one operates, one narrates) to surface reasoning.
- Jakob Nielsen's "five users": test 5, refine, iterate — multiple small cycles beat one big test.
Iteration & requirements
- "Fail frequently, fail fast" (David Kelley/IDEO). Failures = learning.
- The hardest part is getting the requirements right (= solving the right problem). Requirements made in the abstract, or by asking people what they need, are "invariably wrong" — derive them by watching people. Most cases are "special cases."
- Each cycle: observe → ideate → prototype → test, converging over time. The product manager ends it against schedule/budget; final results "only seem to appear in the last 24 hours before the deadline."
Iterative vs waterfall
Iterative (circular, Agile/Scrum) is best for early phases / clarifying the problem; waterfall/gated (linear, management review at each gate) gives control and scales to huge projects. Best practice: iterate inside the stages, between the gates.
Confidence
1.0 — explicit process.
Sources: ["DOET ch.6 'The Human-Centered Design Process' p.221-235"]