Evaluating Software Usability – Think it out loud

“Think it out loud” methodology – user verbalises their through processes.
Useful, for example, when user is navigating a complex UI and they have some familiarity with it and are perhaps performing one than more operation at the same time.
This HCI (Human-Computer Interface) evaluation process evolved from design based approaches to producing qualitative data as part of observational process.
Object not directly measure performance of set of tasks but to describe their feelings and thoughts when carrying out task or series of tasks.
Main problem with “think it out loud” is because of ease of setting up and running, the design of task/tasks may influence the participant to provide positive outcomes irrespective of the usability of interface.
Just by talking about what they are doing/thinking/feeling can affect the behaviour and how they interact with interface.
Should not be considered as an ethical research method.