What is the Hawthorne effect?

• A. The Hawthorne effect is behavior changes due to participants being observed.
• B. The Hawthorne effect refers to sampling bias affecting generalizability.
• C. The Hawthorne effect is the result of random assignment failing.
• D. The Hawthorne effect describes measurement error inflating reliability.

Answer: (A)

The Hawthorne effect is about people changing their behavior simply because they know they are being observed in a study. This idea came from classic workplace studies where workers’ productivity improved not because of the specific changes being tested, but because the presence of observers made them more self-conscious or eager to perform well. This is why the best description emphasizes behavior changes tied to awareness of observation, rather than any manipulation of the experimental conditions themselves. It differs from sampling bias, which is about who is included and how that affects generalizability; from random assignment issues, which concern whether groups are truly comparable; and from measurement error, which is about inaccuracies in how outcomes are measured. So, when you see people behaving differently during observation, it often reflects being studied rather than the experimental treatment itself.