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Observer Expectancy Effect. The observer expectancy effect, also called the experimenter expectancy effect, is a phenomenon that can occur when a researcherâs beliefs or expectations cause him or her to unconsciously influence the participants of an experiment. In order to conserve the internal validity of an experiment, researchers can use a double-blind experimental design.
The experimenter, a stern man in a gray laboratory coat, explained the purpose and procedure: the experiment measured the effects of punishment on learning. One subject was the teacher, who would read a list of word pairs to the other subject, the learner: for example, blue-girl, nice-day..