Today I conducted four Think Aloud tests of a website used in a lot of schools here in Denmark. Unfortunately I did not prepare properly as I didn't think to check weather the test participants already use the website.

I decided to go through with the tests anyway following the same tasks that I had developed thinking the users would not be familiar with the interface.

I think I noticed a couple of usability problems, but I found it very hard to believe in it when the participants know exactly where to look and click throughout most of the test.

My questions to you is:

  • Are my results still valid findings?
  • Is it fine conducting Think Aloud test with users familiar with the interface?

  • What should I have done differently?

2 Answers 2


I feel you are mixing the two (experienced users and thinkaloud) for no good reason.

First-time vs experienced

I assume by your post that your main goal for the evaluation was to identify usability problems.

There is absolutely nothing that states that only first-time users meet the fit-criteria for such purpose. It really depends whether you wish to evaluate the usability for first time users or for experienced ones, which in turn will depend on whether the site was designed more towards this group or the other (sites designed for repeated use, like gmail, may intentionally sacrifice usability for first-time users to gain better usability for frequent users).

Having said that, evaluating with first-time users will nearly always reveal more usability problems than doing so with experienced users (and again, some of these problem may be irrelevant if the site was designed for the latter group). But you'll be surprised how many usability problems you can identify on some systems, even if the participants are daily users with 3 years of mileage.


Thinkalouds are used in evaluation to probe into people minds - to learn what they think first hand, rather than having to subjectively interpret their actions and responses by mere means of observation.

Needless to say, thinkalouds introduce problems of their own, like being a massive hurdle for measurements taking, or the interference itself with puts the whole event even further from a real-world usage.

Whether thinkalouds are done on first-time or experienced users matters not. But like in the previous case, you would typically have greater insights with first-time users - with experienced ones, you are in danger of "I know because I've used it before" type of statements. Yet you can use probing "What would you call it?" to further investigate things.


Are my results still valid findings?

It is impossible to answer without seeing the goals, the process, the results, and your analysis. But if it seems to you unreasonable that you have found usability problems with experienced users - please consider it highly reasonable.

Is it fine conducting Think Aloud test with users familiar with the interface?

It is. In your case, the experienced users is the problem, not the thinkaloud.

What should I have done differently?

It is hard to answer without information about the goals of the evaluation. But seems like you know well that choosing the right participants was key in your case.

As a small tip, when preparing for an evaluation, it is may be easier to start thinking about the exclusion-criteria only then worry about the fit-criteria.


No, your results are not valid

If you designed your usability study intending to observe and test participants who are novice users and you ended up testing experienced users, it's obvious that your data is no good for making conclusions about novice users. As to your second question (can you run think aloud trials on experienced users?), the answer is yes; experienced users are a valuable user group to do usability testing on in many circumstances.

You need to re-run your tests on users that better fit the personas you are designing your thinking aloud tasks for.

Your results might still be useful

That being said, don't throw your data away - usability testing data, even if flawed (like in this case), can still be useful. Some of the tasks you designed might still be applicable to experienced users! You might also be able to use this study to help inform the design of a better study - were there any issues you encountered, etc?

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