You’re defining usability test tasks for a web shop for mobile phones and smartphones. Finding out whether users are able to place an order easily…

A well-defined usability task should be realistic, goal-oriented, and allow for the observation of a user's natural interaction with the system. Option B provides a clear scenario with context (broken phone) and constraints (budget, feature), which represents a typical user's goal. This task structure enables the examiner to assess the entire process from searching and filtering to completing the order, directly addressing the test's main objective of evaluating the ease of placing an order. It avoids prescribing specific steps, which is crucial for identifying potential usability issues.

A: This task is too simplistic and not representative of a real user's goal-oriented shopping behavior.

C: This is a prescriptive script, not a usability task. It tells the user how to act, preventing genuine usability evaluation.

D: This is a background or preference question, not an interactive task that tests the system's functionality or flow.

1. Dumas, J. S., & Redish, J. C. (1999). A practical guide to usability testing. Intellect books. In Chapter 6, "Developing the Test Plan," the authors state that tasks should be "framed as work goals, not as instructions on how to use the interface" and must be "representative of the work users do" (pp. 116-119). This supports option B's scenario-based approach and refutes option C's instructional nature.

2. Rubin, J., & Chisnell, D. (2008). Handbook of Usability Testing: How to Plan, Design, and Conduct Effective Tests (2nd ed.). Wiley. Chapter 6, "Developing the Test Plan," in the section "Creating the Test Scenarios," explains that scenarios should describe a user's motivation and goal, not the interface steps (pp. 128-131). This aligns directly with the structure of option B.

3. ISO 9241-210:2019, Ergonomics of human-system interaction — Part 210: Human-centred design for interactive systems. Section 5.2, "Understand and specify the context of use," highlights the importance of defining tasks based on user goals within a realistic context, which is the core principle demonstrated in option B.