Rachel M. Carmena

Working in a usability lab

Published: 21 June 2019


Rachel, we are creating an app for … (…) … how can we get feedback from real users?

In that moment I recalled my experience when working in a usability lab a long time ago.


They were furnishing a small and comfortable room: a full desk, some bookshelves, several ornamental plants, hidden cameras behind them and a microphone on the table, also hidden.

Next to that room, there was another one with tables and chairs to accommodate more people.

Rachel, would you like to work here until we find usability specialists?

The usability lab

Usability is commonly related to ease of use. However, there are a lot of definitions of usability.

When Steve Krug talks about a usable thing, it means that:

A person of average (or even below average) ability and experience can figure out how to use the thing to accomplish something without it being more trouble than it’s worth.

His first law of usability is:

Don’t make me think!

On the other hand, Jeff Johnson considers 3 components as follows:

  1. It does what the user needs it to do
  2. It does that quickly and safely
  3. It’s easy to learn

He says:

Violins are hard to learn, but they have survived for hundreds of years with little change because they supply the other two more important components of usability.

Jeff Rubin and Dana Chisnell rely on this definition:

When a product or service is truly usable, the user can do what he or she wants to do the way he or she expects to be able to do it, without hindrance, hesitation, or questions.

And they consider five usability attributes: usefulness, efficiency, effectiveness, learnability and satisfaction.

However, Jakob Nielsen considers these other ones: learnability, efficiency, memorability, errors and satisfaction.

The common thing is that if you want to know how usable a product is, you will need information about the use of that product. And that’s what we did in that lab.

When a person was sitting in the first room I described, we observed how that person used an application when doing real tasks.

What was the most important thing? Talking to the people who were going to participate so they could know that they weren’t the object under test but the software application. Besides, I told them the same I tell today when a friend thinks about not being good at using technology:

If you don’t know how to do something, you don’t have any problem. The product has a problem.

We wanted them to be relaxed and to think aloud when performing the tasks to get more information. We recorded the screen, the keyboard, the mouse, the hands, the face and the voice.

How I prepared myself

I received a plan from the lab manager: learning the tools (devices, recording, scoring), studying (materials and books) and practicing.

It included a final point about how to interpret the test results:

  • Common sense
  • Books
  • Experience

How to prepare the lab sessions

I had to prepare four main things among others:

  • Pre-tests to be filled out before using the product. There were different types of forms according to the goal: to get the first impression or the knowledge about the terminology (will they change after the use?), to distribute the participants, etc.
  • Task scenarios with real situations and vocabulary: task selection, successful completion criteria, etc.
  • Post-tests.
  • Deciding the data to be collected during the observation: objective and subjective.

I remember that I found software errors when preparing the sessions, so there were functionalities that I couldn’t include to test and good communication with the companies that had developed the products was required.

Other techniques

Besides the lab, there are other techniques to evaluate the usability:

  • Surveys or interviews
  • An expert or heuristic evaluation
  • A cognitive walkthrough

After reading some books and spending time with the lab manager, I was ready to do some evaluations and I even remember some of them nowadays. I was able to realize things that I had never been aware of. I’ll never forget that experience.

Further reading