Watch people try to do realistic tasks with your design. You learn where it fails, which is something no amount of asking will tell you.
Written as practical advice. Where a step rests on established research practice, the source is listed under References. Nothing here is a universal rule.
Say who you are and that you are testing the design, not them. Confirm consent and recording.
"Tell me what you are thinking as you go." Show them briefly what you mean.
Read it out, hand it over in writing, and then stay quiet.
Note hesitation and backtracking. Do not confirm whether they are right.
"What makes you say that?" "What would you expect to happen?"
Ask what stood out, thank them, and store any personal data securely.
Weak
Click Settings and change your email.
Better
You recently changed your email address. Show me how you would update it here.
Why. The first names the button, so it tests whether they can follow instructions.
Weak
Tell me where you would click next.
Better
Find a film you would like to see on Sunday afternoon.
Why. Ask people to do the thing, not to describe how they would.
Weak
Go to the site, sign in and find your transcript.
Better
Look up the results of your midterm exams.
Why. Steps contain hidden clues about how the interface works.
Senior designer note“If your usability task tells participants where to click, you are testing their ability to follow instructions.”
References