Video recording is usually coupled with some form of audio record, which is known as verbal protocol. Sometimes this verbal protocol may contain users' spoken observations, this adds an extra dimension to the information gathered by addressing the cognitive activity underlying the user's physical behavior. From such a protocol it is possible to obtain a wide range of information such as, for example, the way that the user has planned to do a particular task; her reactions when things go wrong; her identification of menu names or icons, and so on.
You may even get a clue about her subjective feelings about the activity from comments and the tone of her voice. Sometimes verbal protocols may be collected on their own without video, either because the video added little extra information or because for some logistical reason use of video was not feasible.
What is think-aloud?
A think-aloud protocol is a term given to a special kind of verbal protocol in which the user says out loud what she is thinking while she is carrying out a task or doing some problem-solving. Verbal protocols place added strain on users, who are required to do two things at once - the task itself and talk about their actions or what they are thinking about. Evidence from cognitive psychology shows that humans are poor at maintaining divided attention for more than a few minutes so you will need to think of ways to support users if you want to collect this kind of data.
Think aloud benefits in usability testing
When the user thinks aloud, what he or she might miss in the interface design becomes clear. This produces valuable data on how to improve the user interface. For example, the facilitator or observer might be very surprised when a user does not click on a call to action button that has been optimized and positioned in a prominent spot of the page layout. This could be due to the color of the button or the text on the button label. In usability testing, there are frequent surprises in how users interact with a prototype. By using the think-aloud protocol in this process, designers and usability experts can better understand the logic behind these revelations.
The running of a think-aloud usability test
In a usability test, the test user is asked to say everything that he or she is thinking throughout the test and say why he or she is doing it. This will enable the moderators to see how the test user might use the technology in a different way than how they predicted and also understand the reasons behind this. The product or prototype will then be modified based on this feedback.
If you are trying to find out why someone cannot use a feature of the system that you thought was quite straightforward you will want to find out what the person is thinking and planning to do so you need to overcome the silence in a way that encourages her to give you this data. One way of doing this is to arrange for two users to work together so that they talk to each other about their thoughts. Allowing users to ask questions if they need to and providing minimal answers, just enough to keep them going, is another variation that you can try. The level of user experience is important for both paired-user and question-asking protocols. In some studies, the researchers have arranged the paired-user situation so that a more experienced user has to teach her less-experienced partner how to use the interface. Alternatively, protocols can be obtained after the tasks have been completed. These are known as post-event protocols. With this technique, users view videos of their actions and provide a commentary on what they were trying to do. This is often used in situations where the tasks require careful concentration and are time-critical, such as air traffic control rooms, where it may be the only feasible way to collect verbal protocols. However, there is some debate on the extent of the differences between "think-aloud" protocols and those collected after task completion, and it should be noted that the post-event protocols can contain recalled information that was not used during the task sequence: hindsight can produce a rationalization of the user's own action. Conversely, however, some researchers report that when users are invited to participate in data analysis, it is often very beneficial because they are stimulated to recall useful details about their problems.