For a long time before Rosenhan conducted his experiment, there had been historical attempts to classify abnormal behavior. Notably, the medical model was the most common approach to understanding and classifying abnormal behaviors. The medical model focuses primarily on the treatment of mental illnesses (Kleinman, 2012). The model is also known as psychiatry where psychiatrists are doctors along with other professionals trained to manage mental illnesses. Since the early 1950s, the medical approach has been used for the Diagnostic and Statistical Manual of Mental Disorders (DSM) to classify abnormal behaviors. However, in the 1960s, the model was strongly criticized especially among psychotherapists and psychiatrists. This criticism led to the anti-psychiatry movement. The movement's concern was that the principles of the medical approach were flawed in correctly classifying and identifying people with abnormalities (Huss, 2009). David Rosenhan was among the critics of the medical model and in response decided to conduct an experiment that would be more effective; an alternative to the medical model. The main purpose of Rosenhan's experiment was to test the hypothesis that, using the medical model, psychiatrists could not reliably identify the difference between healthy and insane people. Therefore, he participated in a field experiment in which he managed to manipulate the symptoms of pseudo patients (Huss, 2009). Additionally, the study involved participant observation; upon admission, the pseudo-patients took notes on how the departments worked and how they were treated individually. This research experiment was conducted in two parts: The first part involved 8 sane people who were psychology graduate students in their twenties. The research also involved: A painter Three psychologists A pediatrician A housewife These participants tried