Why is blinding important in research?

Blinding is important to reduce research bias (e.g., observer bias, demand characteristics) and ensure a study’s internal validity.

If participants know whether they are in a control or treatment group, they may adjust their behavior in ways that affect the outcome that researchers are trying to measure. If the people administering the treatment are aware of group assignment, they may treat participants differently and thus directly or indirectly influence the final results.