When researchers' biases influence the participants of an experiment.
The observer expectancy effect, also known as the experimenter expectancy effect, refers to how the perceived expectations of an observer can influence the people being observed. This term is usually used in the context of research, to describe how the presence of a researcher can influence the behavior of participants in their study.
Every research interaction is a delicate ballet between objective observation and unconscious influence. Even the most experienced researchers must navigate this complex dynamic, where their knowledge and assumptions can inadvertently guide participants toward expected behaviors, potentially masking crucial insights about genuine user needs.
In design research and usability testing, this effect manifests when researchers unknowingly guide users toward preferred interactions or when test facilitators give subtle cues about "correct" paths. These unconscious influences can compromise the validity of user research, leading to design decisions based on biased data rather than authentic user behavior.
The impact extends beyond immediate testing scenarios into the entire design process, affecting everything from initial user interviews to final usability validations. Understanding and controlling this effect is crucial for maintaining the integrity of user-centered design processes.