Think aloud

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Created: SannaH (29 Nov 2007)
Last edited: hamishwillee (06 Feb 2012)


Introduction of usability testing

Usability testing is a method to evaluate a product by testing it on the proposed end user. This gives emperical data about the efficacy and ease of use of the product. This exercise if carried out in an iterative model often helps in diagnosing problems and thereby finding their solutions at a much earlier stage of the development process compared to other approaches where the problems are often diagnosed at a very later stage leading to huge cost and time over-runs. It is important to involve the user at every step of the development process to ensure that the ensuing end product would meet their requirements and usability criteria.

Though considered an expensive exercise at times, usability testing has slowly come into its own in terms of acceptability and most companies now spend considerable time and effort to ensure that the testing is carried out well to reduce after sales and support efforts later on. There are many techniques of usability testing, one of which is think aloud.

Introduction of think aloud protocol

“Think aloud protocol is a technique applied in user testing where users are asked to vocalise their thoughts, feelings and opinions while interacting with a site as they perform a task. While the focus in user testing is primarily on how effectively a user performs the required tasks (and not on how users believe they are performing), verbalizations are useful in understanding mistakes that are made and getting ideas for what the causes might be and how the interface could be improved to avoid those problems.” [The explanation is taken from Usabilitycompany.com


The users are given the product/service to test rather use, and when they are doing so they are asked to express themselves. This means that say the user is going to dial a call using your dialer, he speaks out the steps involved, the things/inputs he makes, how easy or complicated is it use to the dialer to actually place the call, whether the features were in line with his/her expecatations etc. This would then help in understanding what are the user’s thoughts during using the application, whether the user interface was self explanatory and easy to use, where were the variance in terms of user expectations etc.


With think aloud protocol you can gather information about how the user uses the application and you will get to the bottom of the reason why your application is interpreted in the wrong way. Maybe it’s the terminology, maybe the user is used to finding certain features in certain places and now they are not there. When the user says out loud what and why s/he is doing you can “read her/his mind” and learn more about your user. That helps to locate the problems of your application and make improvements.

Comparision with other techniques

Much like think aloud there is another almost similar technique talk aloud in which the users are just asked to describe their actions, they don’t actually explain their actions. This is supposed to be more objective as the investigator gets the data points about how the user is using the application and not his/her rationale. This helps in understanding whether when the user is performing the task does it appear complicated to them, whether the interfaces are easy to use etc.

Additional Resources

Think Aloud Protocol on Wikipedia

Usability first glossary

HCI lecture series


Usability Testing

Heuristic evaluation

Mobile testing


This page was last modified on 6 February 2012, at 06:47.
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