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HCI Lecture 5
The details of this lecture are available on pages 12-14 of the handout.
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The main points to be addressed in this lecture were:
- What is a think-aloud protocol?
- In what way(s) can their usefulness be optimised?
What is a think-aloud protocol?
Think aloud protocols consist of observing a user working with an interface
while encouraging them to "think-aloud"; to say what they are thinking and wondering
at each moment. Think-aloud protocols are of particular value because they
focus on the problems a user has; when the user is working without difficulty, direct observation (and hence the think-aloud protocol itself) is
of very limited use. This is because the user is unable to communicate as fast
as they think and
act, unless a specific problem arises which slows them down. It is at these
times when this method really shines as it allows the observer to correlate the
actions and statements of the participant.
We see the main advantages of this method as:
Furthermore, the protocol may be used in two distinct scenarios.
- Rapid, high-quality, qualitative user feedback (e.g. as compared with
- Data is available from a broad range of sources, such as:
- Direct observation of what the subject is doing.
- Hearing what the subject wants, or is trying, to do.
- If the subject gets into difficulties, the observer has
the chance to clarify the situation.
- High degree of flexibility; the experiment may easily be steered by the
- The presence of two people allows meaningful, direct dialogue.
- The observer specifies a definite task to be accomplished by the subject.
- This allows the observer to concentrate on a specific task they are
- 'Open-ended'; no task is specified, and the user is free to choose their own task.
- Allows the observer to concentrate on naturally occurring problems
In what way(s) can their usefulness be optimised?
This may be answered by giving an overview of how a think-aloud protocol should
be conducted in practice, in order for its results to be realistic and helpful
to the observer. The purpose of the experiment, e.g. to examine in detail a specific 'corner' of
the interface, or to gain an outline of its general efficacy, should of course
be decided upon initially. This will allow the observer to choose one of the
scenarios given above, and to tailor the protocol accordingly.
As an observer, you need to make sure of the following:
- That user realises that the interface, not they, are under scrutiny.
- That the user should at all times comment liberally on his/her actions,
intentions and thoughts.
- That the user is at ease. This involves explaining that you may give only a
bare minimum of help to the user, and apologising in advance for
this. The user should try to find their own way as much as possible.
- Any help given to the user should be carefully thought out, in order for
its effects to be recorded as part of the experiment.
Use of video recording equipment
- The main task of the observer is to jot down what happens.
- The moment when an observer notes what a subject is doing/saying only occurs once and thus needs
to be recorded.
- This can be aided by a structured data sheet, can include categories to
observe and also prompts
- Note taking is still relevant even when videoing the experiment as the video representation
cannot capture everything and there is no way of clarifying ambiguities when watching a video.
- Useful because session can be recorded for later analysis
- With the observers usual position beside the participant they may miss
- BUT, for the reasons specified above, note taking is still vital
- For monetary and accuracy reasons an effective alternative to the videoing
of a session may be to simply repeat the session with different participants
Use of Prompts
There is a considerable difference between prompting and biasing the user,
basically say as much as necessary to keep user happy without helping and
making suggestions. Such questions may include:
- What are you thinking now?
- Why did you do that?
If a subject is completely stuck a decision may have to be made as to whether
to help the participant or not.
It is up to the judgement of the observer, but if a decision is made to
allow some help the following should be noted:
All of the above maximise the effectiveness of the experiment by noting the
effect of your input.
- Ask what the user would do if the oberver wasn't there
- Take a note of what you said and what happened afterwards
- Was the problem solved?
Usually done informally at the time by careful note taking but a more
quantitative content analysis can be done by examining video evidence after
The method is informal and the most effective single way to maximise
effectiveness is to create an informal atmosphere.This is where the subject can
feel relaxed and as unaware as possible that their actions are being recorded.
As mentioned above hints may well contribute to such an informal atmosphere.
The Think-Aloud Protocol is a very perceptive and informative method and when
used effectively can result in a lot of information, regarding an interface
etc., being discovered that might not otherwise have been. It is however noting
that there are many ways to lessen its effectiveness and it is expensive in
investigator and subject time.
This page was created by Angus Beaton, Steven Nicholson, Neil Halliday & Keith