Usability Testing

Learn how to test if your software is actually easy to use. Covers heuristic evaluation, user research basics, and the think-aloud protocol.

Manual QA • Module 3 • Lesson 2
10 min read

What you'll learn

  • Understand what usability testing is and why it matters
  • Run a heuristic evaluation using Nielsen's 10 principles
  • Conduct a think-aloud session with a real user
  • Tell the difference between a usability bug and a functional bug
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Usability Testing

Software can work perfectly and still be terrible. Usability testing asks a different question: can a real person actually use this?

Usability Bug vs Functional Bug

Functional Bug

  • The thing is broken
  • Button does not respond when clicked
  • Form submits the wrong data
  • Page throws a 500 error
  • Found by checking requirements
  • Fixed by changing the code logic

Usability Bug

  • The thing works but confuses people
  • Button works but nobody can find it
  • Form works but label is unclear
  • Page loads but users give up
  • Found by watching real users
  • Fixed by changing design or wording

VerdictA working product that nobody understands is just as bad as a broken one.

Quick check

Question 1 of 10 correct

A user cannot find the 'Delete Account' option even though it exists in Settings. Which kind of bug is this?

Nielsen’s Heuristics

Jakob Nielsen wrote 10 rules for good design. These are the most important ones.

The Think-Aloud Protocol

The best way to find usability bugs is to sit next to a real user and listen to them think.

  1. 1

    Recruit

    Find 5 real users who match your target audience. Not your mom. Not your coworkers. Real users.

  2. 2

    Brief

    Tell them: 'Say everything you are thinking out loud. There are no wrong answers. We are testing the product, not you.'

  3. 3

    Give the task

    Hand them a real task: 'Please order a pair of red shoes in size 9.' Do not tell them how. Watch them try.

  4. 4

    Listen and observe

    Stay quiet. Do not help. Write down where they hesitate, click the wrong thing, or say 'hmm...'

  5. 5

    Debrief

    After the task, ask open questions: 'What was confusing? What did you expect to happen?'

What to Watch For

How Bad Is It?

Not every usability issue is equally serious. Rank them so the team fixes the worst ones first.

Catastrophic
Major
Minor
Cosmetic
  • Catastrophic:Users rage-quit or call support.
  • Major:Users finish but with heavy frustration.
  • Minor:Small friction — users still complete.
  • Cosmetic:Visual polish issue only.
Severity of usability issues.

A/B Testing

Common Mistakes

Practice: Match Heuristic to Violation

Drag each design problem to the heuristic it violates.

Quiz

Question 1 of 30 correct

You run a think-aloud session. The user stops talking, sighs, and finally asks you where the 'Submit' button is. Which signal is this?