I was taught that one of the most important aspects of moderating usability study sessions was to encourage participants to think out loud as they worked on tasks. While the technique is good and useful in many usability test situations, it isn’t always the best approach.
Get data about how and why people do things
This “verbal protocol,” as it is known, can be an extremely useful thing to have. If the participant is good at thinking aloud, you all hear about how how she is forming the task and how she is thinking about reaching her goal. You will hear about why she is doing the things she is doing, and the words she uses to describe it all. You also will get verbal feedback about how the participant feels about what is happening because she may say that she’s frustrated, or annoyed or even happy.
What the data means
Hearing how a participant forms a task tells you whether the designers and the user are thinking of (modeling) the task in the same way.
Hearing why a participant is taking a particular step tells you where your design does and does not support users’ goals.
Hearing the words gives you labels for navigation, links, and buttons. Your information architecture should match the participant’s vocabulary.
Hearing the emotion tells you how severe a problem may be.
These are all good things to know.
How to get a good think-aloud
Some people think aloud naturally, or at least will verbalize their questions and frustrations just because there’s someone else in the room (that would be you, the moderator). But most people need to be primed to do it, and some even need practice doing it.
In your introduction to the session, ask participants to tell you what’s going through their minds as they do tasks.
Consider incorporating a practice task that lasts for half a minute, just to get participants to try it out. Encourage them and quickly move on.
When you describe the task scenario to participants, remind them to think aloud.
During the task, when something seems to be frustrating, annoying or hindering -- and the participant isn’t talking -- ask her to tell you what she’s thinking.
Know that there’s more going on than you can hear
People filter automatically
Participants can’t tell you everything they’re thinking. And really, you don’t want that. Humans can process on a number of cognitive tracks at the same time. Most study participants will automatically be able to distinguish between what is related to the situation and what isn’t.
This is a test
They also may filter what they tell you beyond this basic distinction. For example, they want to do well. Although you tell participants you are not testing them, a participant might feel some level of test, even if she’s just in competition with The Machine.
Participants may fear failure or embarrassment. In usability studies, people often persist at times when they would normally ask for help.
People tend to give positive feedback
Participants want to give you a good session. People are conditioned to say and do things for the approval of others. They want the moderator to approve of their performance.
Participants take responsibility for bad design
People who are novices at a task or are working with something outside their experience may excuse the design by taking responsibility for a design problem. For example, they may say they could do it now that they (have failed and) have done it once. Or they just need more time to learn the site. This is especially common among older adults who are unsure of their computer or other appropriate skills.
When you might not want to use think-aloud
There are times when using think-aloud can conflate or dilute your data. There are other situations in which using think-aloud is just difficult, or won’t work for the type of participants you have in your study.
Time on task
If you want to measure how much time it takes people to complete a task because you are particularly concerned with efficiency, introducing think-aloud is probably a bad idea. Talking about what you’re thinking slows you down while you choose words to convey your ideas about what’s happening and why.
Audio feedback in a user interface
Some interfaces incorporate audio feedback to indicate statuses or modes. These auditory cues may be overlapped by the participant talking so the participant may miss something important happening – or you might. Also, many blind people and people with severe vision impairments use screen readers to use software and web sites. If you’re tuned in, you can learn things by listening to the screen reader as it works. And, although most of the people with visual disabilities who use screen readers who I have observed can listen and talk at the same time (like sighted people can see or read and talk at the same time), as a sighted moderator, my auditory channel is challenged by listening to both the screen reader and the participant at the same time.
You’re interrupting a taxed thought process
People who have short-term memory loss, are medicated, or have other cognitive limitations tend to stop talking when they encounter obstacles to reaching their goals. You might be tempted to prompt these people to “tell me what you’re thinking,” but try not to. They’re concentrating on working around the obstacle. If you watch closely, you can see their solution unfold. After it does, then ask them about how they got to it.
An alternative to think-aloud: Retrospective review
“Retrospective review” is just a fancy name for asking people to tell you what happened after the fact. Go back to a particular point in the task, set the context, and ask the participant to tell you what was happening. For example, say something like this: “When you got to this point on the registration form [pointing to a field], you stopped talking. Tell me about what you were trying to do and what was happening.” The participant may revise what happened, but you will have good notes and the memory of someone who was observing closely, not trying to perform, so you can pinpoint issues that you thought were happening. Invite the participant to correct your perceptions.
If you have the tools and time available, you can go to the video recording so the participant can see what he did and respond to that by giving you a play-by-play commentary.
It’s a great tool, used at the right time with the right participants
Think-aloud or verbal protocol can give you rich data about vocabulary and effectiveness of design. From it, you can also get some impression of the severity of problems for a particular participant or the level of satisfaction for someone who had a positive experience. Use think-aloud in exploratory or formative studies to help you understand how users are modeling their tasks. Consider carefully whether to use it in other situations, though, to ensure that you’re not adding to the cognitive load that the participant is already experiencing.