At the Canonical Design blog, Tingting Zhao has written a detailed look at defining and articulating the "tasks" that are given out as prompts in usability testing. This includes finding the correct amount of detail, as well as navigating the distinction between closed- and open-ended tasks, or "direct" and "scenario" tasks. With scenario tasks, for example, "some participants may experience uncertainty as to where to look and when they have accomplished the task. Others may be more interested in getting the test done, and therefore do not put in as much effort as what they would in reality."
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