The effect of experimenter bias on the performance of the albino rat


  • We want to thank Dr. Ralph H. Kolstoe for his advice regarding animal handling procedures, and Miss Linda L. Vikan and Mr. Gordon Persinger, National Science Foundation Undergraduate Research Participants, for their assistance in the conduct of this experiment and in the analysis of the results.


That an experimenter can very easily influence his subjects to give him the response he wants is a problem that every investigator recognizes and takes precautions to avoid. But how does one cope with the problem of unconscious influence? It is possible that a good many contradictory or unexpected findings are due to the fact that the experimenter unknowingly communicated his desires or expectations to his subjects. Though this problem has been generally recognized and much discussed, there has heretofore been no systematic test of the hypothesis that an experimenter can obtain from his subjects the data he expects or wants to obtain. This paper reports just such a test, and discusses what can be done to avoid experimenter influence, both conscious and unconscious.