• Think-aloud involves someone thinking aloud during an activity.
  • Think-aloud gives insights into what people are noticing during a task.


  • Inexpensive
  • Useful for seeing what really happens
  • Good for finding out the reasons for what happens


  • Give fragmented insights, not a clear overview

A transcript from a think-aloud session

Well, this looks like… it’s not a bad design overall for a watering can, but they’ve used bronze for the sprinkler part here, which is… it’s a sensible choice in terms of corrosion, of avoiding corrosion, but you need to think about galvanic corrosion here, where you, it’s steel, so that would cause problems. Maybe not a big problem for a small domestic item like this, but it’s something that would be a problem in a big industrial application.

What you need:

  • An activity for the participant to perform
  • The tools, materials etc needed for the task
  • A recording device and/or paper for notes


  • You won’t be able to keep accurate handwritten notes in real time while also observing what’s happening.
  • People are usually OK with being audio recorded, and quickly stop paying attention to an audio recording device.
  • People are usually self-conscious about being video recorded, and this usually lasts through the recording session.


  • Explain what you would like the participant to do.
  • Give them a quick demonstration involving an activity from an area that’s very different from the one they’ll be doing, to avoid bias.
  • Make it clear that there are no right or wrong answers.
  • Tell them that if they’re silent for more than a specified time (e.g. 5 seconds) you’ll prompt them to say what they’re thinking about.


Tip: Don’t let them see the material until you’ve finished your demonstration, or they’ll start doing the task  before you’ve finished explaining.


  • Resist the temptation to talk, make suggestions, or help; you’re trying to find out about the participant’s knowledge, with as little bias or steering as possible.
  • Make a note on paper or mental note of any significant actions that would not appear on the recording.
  • If they are silent for more than the agreed time, use a non-directive prompt, such as: “Could you tell me what you’re thinking about?”


  • Once you have identified the key actions and concepts, you can collect quantitative data using various approaches.
  • Timelines let you see what is happening when; for instance, how often people hesitate or swear when they try to use a particular feature.

The timeline below shows which actions occur in which sequence, with each column representing a change in the action being performed. The first column shows that the person is reading; next, in the second column, they hesitate, and then they click an option, followed by swearing.

This is the most basic form of timeline; it shows the sequence of actions, but not how long each action lasts. More sophisticated timelines show duration, but these are difficult or impossible to fill in while the person is performing the task, and usually have to be completed from the recording of the session. The simplest form of timeline can often be filled in during a task.

Timelines are useful for showing where problems occur, and how often a particular action occurs (for instance, if people are repeatedly swearing while trying to use a prototype product, then that usually tells you where there’s a problem with the design).

You can use the outputs from these methods (e.g. concepts identified as important) as inputs for other methods, for instance within visual analogue scales.

These approaches can be used to identify places where hesitations and errors often occur, so that the causes can be designed out of the system (whether the system is a software, bureaucratic, or physical system).

Copyleft Hyde & Rugg 2021