User Centred Design

User-centred design (UCD) — also called human-centred design (HCD) — grounds every design decision in evidence about real users' needs, behaviors, and context, gathered and re-checked iteratively, rather than in assumption or internal opinion alone. ISO 9241-210 is the formal standard defining the process; this skill covers the working method.

The iterative cycle

1. Understand context of use — who the users are, what they're trying to do, and the environment/constraints they do it in.
2. Specify requirements — user needs and success criteria derived from that understanding, not just business requirements.
3. Produce design solutions — from low-fidelity (sketches, wireframes) to high-fidelity (interactive prototypes), evaluated and refined in rounds rather than shipped from a single pass.
4. Evaluate — usability testing and other feedback methods, against the requirements from step 2 — and loop back to step 1 or 3 based on what's learned.

The cycle repeating — not any single step — is the actual discipline; doing one round of user research and then never revisiting it isn't UCD, it's research-informed design done once.

Research methods

• Qualitative (why/how): contextual inquiry (observing users in their real environment), semi-structured interviews, diary studies, think-aloud usability testing.
• Quantitative (how much/how many): analytics, A/B testing, surveys with closed questions, first-click testing, tree testing (navigation structure validation).
• Generative vs. evaluative — generative research (early, open-ended, "what should we build") explores the problem space; evaluative research (later, "does this specific design work") tests a concrete artifact. Confusing the two — running a usability test on a blank-slate problem, or an open-ended interview when a specific prototype needs validating — wastes both the method and the participants' time.

Personas and journey maps

• A persona is a composite, research-grounded representation of a user segment — useful for keeping a team's mental model of "the user" aligned and evidence-based; harmful the moment it's built from assumption rather than actual research and then treated as fact.
• A journey map traces a user's steps, thoughts, and emotions through a task or process over time, surfacing pain points and gaps between touchpoints (including ones outside the product itself) that a screen-by- screen view misses.

Usability testing

Watch a representative user attempt real tasks with a prototype or live product, using a think-aloud protocol (narrate what they're doing and why) — the moderator observes and asks follow-up questions but doesn't lead the participant to a "correct" path. 5 users per round is a widely-cited (if debated) rule of thumb for catching most usability issues in a single round at low cost; more rounds with fewer users each catches more issues overall than one large round, because the design changes between rounds.

Accessibility as part of UCD, not separate from it

Designing for the full range of human ability (vision, hearing, motor, cognitive) is part of understanding real context of use, not an add-on compliance step after design is "done." WCAG conformance (see HTML's accessibility section for concrete technique) is a minimum bar, not a substitute for testing with people who actually use assistive technology.

Common pitfalls

• Skipping straight to solutions — designing screens before understanding the actual user need risks solving the wrong problem elegantly.
• Research theater — running interviews or tests but not actually changing the design based on what's learned; if findings never affect a decision, the research step isn't doing its job.
• Recruiting convenient participants instead of representative ones — testing with colleagues or friends who aren't the target user segment produces confident-sounding but misleading results.
• Treating a persona as demographic decoration — a persona built from guesses about age/job title rather than actual behavioral research patterns gives false confidence without the grounding UCD is meant to provide.
• One round of testing, ever — a single usability-test round validates one specific design snapshot; it doesn't validate that the next set of changes is also good, which is why the cycle is iterative by definition.

Learn more

• ISO 9241-210 — the formal human-centred design process standard.
• Nielsen Norman Group — widely-cited practitioner research and methodology guidance.
• GOV.UK Service Manual: User research — a real, public, government-scale UCD process.
• HTML for concrete web-accessibility technique that UCD's inclusive-design principle depends on.