The role of the experimenter in a concept learning task

Since the Renaissance scientific experimentation has been plagued by the experimenter's effect upon the observation, collection, and reporting of data. Only recently, however, has this variable been recognized as one that can be investigated. Psychological experiments with animal and human subjects in clinical, experimental, social, survey, and educational research have shown that experimenters can and do influence their data. Specific factors which have been investigated include experimenter's status, prior experience, previous interaction with subject, modeling effects, early data returns effects, sex, and expectancy. This experiment was designed to investigate the effect of experimenter's expectancy. The experimenter was told he was dealing with two different groups—a bright one and a dull one--and that these two groups would perform very differently in a concept learning task. A 2x2x2x4 mixed hierarchical analysis of variance desgn was used, with eight experimenters testing 64 subjects. No significant effects were found. A discussion follows, and the differences between this study and others which found significant differences in their results are explored. In future experiments it is suggested that the experimenter be given an opportunity to score, summarize, and interpret his data, and that the subject be allowed to make subjective judgment of his behavior in relation to his perceived idea of whether or not he is pleasing the experimenter, and, if not, an opportunity should be provided for him to be able to alter his own behavior in keeping with the set or expectancy of the experimenter.