Why a Moderated Session Isn't the Same as Unobserved Behavior
A participant in a moderated usability test behaves more carefully and deliberately than they would unsupervised, simply because they know someone is watching.
What's this effect called, and what's one recommended mitigation?
The correct answer is "The Hawthorne effect; frame the session as testing the product, not them."
This subject names the effect directly: people behave differently simply because they know they're being observed — a specific risk for contextual inquiry and moderated usability testing, less so for passive, unannounced methods like analytics. The recommended mitigation is framing the session as testing the product, not the participant ("we're testing whether the design works, not whether you can use it"), and leaning on behavioral/passive data when the effect would specifically distort the finding needed.
The distractors mismatch the effect or the mitigation: social desirability bias is a related but distinct effect, about giving answers that make the participant look good rather than about being more careful because they're observed, and "only ask yes/no questions" isn't this subject's stated mitigation for either bias; confirmation bias is about the researcher's synthesis, not the participant's behavior during the session; and recruiting bias is about who's in the study, not about how being watched changes behavior mid-session.
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