“The Eye of the Beholder”: A Classroom Demonstration of Observer Bias

Abstract

In a class demonstration of observer bias, students were led to believe that the response time of a subject's performance would decrease across three trials of a mirror-tracing task, due to alcohol consumption. The subject (a trained confederate who actually drank a nonalcoholic beverage) maintained consistent behavior and performance across trials. Students reported a trend that was consistent with the expectancy yet was not present in the behavior observed. The demonstration had a strong and memorable effect on students. We discuss the value of this classroom exercise for demonstrating observer bias.