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Research methodEstablished researchFoundational

Usability Testing

Watching people attempt real tasks, which is the most direct evidence available about whether a design works.

Definition

Usability testing observes participants completing tasks with a product or prototype. The output is behaviour: what people did, where they hesitated, and what they failed at. Opinions gathered alongside are secondary.

Established research. Originates in published research and has been replicated. The effect is real. Its size in your product still needs measuring.

On this page
  1. Definition
  2. Running a session
  3. In practice
  4. Sources
  5. Continue from here

Running a session

  1. 1

    Write tasks, not instructions

    'Find a hotel in Lisbon for next weekend under 200 euros' is a task. 'Click the search button' is a script.

  2. 2

    Say what you are testing

    Tell the participant you are testing the design, not them, and that any difficulty is useful information.

  3. 3

    Stay quiet

    Silence produces data. Answering their questions destroys it. When asked, redirect: 'What would you expect to happen?'

  4. 4

    Record behaviour, not just opinion

    Task success, time, errors, hesitations and the recovery attempt when something goes wrong.

  5. 5

    Debrief afterwards

    Ask opinion questions at the end, so they do not contaminate the tasks.

Do

  • Test early, with rough prototypes, when changes are still cheap.
  • Test with people from outside the team and outside the domain.
  • Report task success rate alongside quotes.
  • Include participants who use assistive technology.

Do not

  • Ask whether participants like it.
  • Lead with questions that presuppose an answer.
  • Rescue a struggling participant before the struggle has told you something.
  • Treat satisfaction ratings as evidence of usability.

In practice

Unmoderated testing at scale

Remote research

Unmoderated platforms trade the ability to probe for larger samples and faster turnaround. They suit validating a specific known question and are poor for open exploration.

Sources

Where a source establishes something narrower than the popular reading of it, the note says so.

  • A mathematical model of the finding of usability problems

    J. Nielsen and T. K. Landauer, INTERCHI, 1993

  • Beyond the five-user assumption

    L. Faulkner, Behavior Research Methods, Instruments, and Computers, 2003

Continue from here

Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.

Applies when you are designing

A CheckoutA DashboardA Data TableA FormA Mobile AppA Pricing PageA Search ExperienceAn AI ProductAn Ecommerce ExperienceAn Onboarding FlowAuthentication

Explains

The mechanism underneath these entries.

  • Curse of KnowledgeCognitive bias

    Testing exists because you cannot un-know your own interface.

Principles behind this

The reasoning this solution is an application of.

Often used with

These usually appear in the same screen or the same decision.

Alternative approach

A different answer to the same problem, with a different cost.

  • Guerrilla TestingResearch method

    Cheaper and faster, with a sample you did not choose.

  • Heuristic EvaluationResearch method

    Expert judgement finds different problems from watching real people, and finds them before you have users.

Commonly confused with

Close enough to be mixed up, different enough to matter.

  • A/B TestingResearch method

    One tells you why something fails with five people. The other tells you which version wins with thousands, and not why.

Short definition

The one-paragraph version, for when that is all you need.

Related concept

Connected closely enough to change how you apply this.