“Task analysis is used mainly to investigate an existing situation, not to envision new systems or devices. It is used to analyze the underlying rationale and purpose of what people are doing: what are they trying to achieve, why are they trying to achieve it, and how are they going about it? The information gleaned from task analysis establishes a foundation of existing practices on which to build new requirements or to design new tasks.
Task analysis is an umbrella term that covers techniques for investigating cognitive processes and physical actions, at a high level of abstraction and in minute detail. ”
From: Preece, J., Rogers, Y., Sharp, H. (2002), Interaction Design: Beyond Human-Computer Interaction, New York: Wiley, p.231