During usability tests, participants are asked to narrate theirthoughts. Applying the concurrent think-aloud method (CTA), theverbalization happens simultaneously while participants are interactingwith the test product. This enables the moderator to develop a betterunderstanding of which contents the participants are engaging with, whatthey are thinking, whether questions arise or what participants arefeeling. This method is very well suited for identifying usabilityproblems. Moreover, it also is time saving, as it is applied whileparticipants are completing the test tasks.

The concurrent think-aloudmethod has also been criticized: experiments have shown that because ofthe simultaneous verbalization of thoughts, the completion of test taskssometimes takes longer. CTA can also have an effect on the success oftask completion. Because they are thinking aloud, some participantsreflect more on what they are doing and are able to better organizetheir thoughts.

Also view: Retrospective Think-aloud