In a double-blind experiment, which statement is true?

• A. Neither the participants nor the researchers know who receives the treatment.
• B. Only the researchers know who receives the treatment.
• C. Only the participants know who receives the treatment.
• D. Both the participants and the researchers know who receives the treatment.

Answer: (A)

Double-blind design hides who is getting the treatment from both the participants and the researchers to prevent bias. When neither side knows who receives the real treatment, participants’ responses aren’t swayed by expectations, and researchers’ ratings or interactions aren’t influenced by knowledge of who got the treatment. This helps ensure that any differences observed are due to the treatment itself, not to placebo effects or observer bias. In practice, the assignment is randomized and coded, often by a third party, and the code isn’t revealed until after data collection and analysis. That’s why the true statement is that neither the participants nor the researchers know who receives the treatment.