The Monster Study is the name given to a stuttering experiment performed on twenty-two orphan children in Davenport, Iowa in 1939. It was conducted by Wendell Johnson at the University of Iowa. Johnson chose one of his graduate students, Mary Tudor, to conduct the experiment and he supervised her research. After placing the children in control and experimental groups, Tudor gave positive speech therapy to half of the children, praising the fluency of their speech, and negative speech therapy to the other half, belittling the children for every speech imperfection and telling them they were stutterers. Many of the normal speaking orphan children who received negative therapy in the experiment suffered negative psychological effects and some retained speech problems for the rest of their lives. Dubbed "The Monster Study" by some of Johnson's peers, who were horrified that he would experiment on orphan children to prove a hypothesis, the experiment was kept hidden for fear Johnson's reputation would be tarnished in the wake of human experiments conducted by the Nazis during World War II. The University of Iowa publicly apologized for the Monster Study in 2001.
Patricia Zebrowski, University of Iowa assistant professor of speech pathology and audiology, notes, "The body of data that resulted from Johnson's work on children who stutter and their parents is still the largest collection of scientific information on the subject of stuttering onset. Although new work has determined that children who stutter are doing something different in their speech production than non-stutterers, Johnson was the first to talk about the importance of a stutterer's thoughts, attitudes, beliefs, and feelings. We still don't know what causes stuttering, but the 'Iowa' way of approaching study and treatment is still heavily influenced by Johnson, but with an added emphasis on speech production."