Background: The medical model attempts to group symptoms of abnormal behaviour and classify mental illnesses accordingly. This is also known as psychiatry. Beginning in the 1950s this medical approach has used the DSM to classify abnormal behaviours. However, in the 1960s a number of psychiatrists and psychotherapists, known as the anti-psyhciatry movement started to criticise the approach. Rosenhan can be seen criticising this model in this study as he wanted to demonstrate that psychiatric classification is unreliable. Aim/M&P: To test the hypothesis that psychiatrists can't reliably tell the difference between sane people and insane people. The main study is an example of a participant observation; done by several pseudo-p's (a researcher pretending to be a patient), took detailed notes of their time on the ward. A small natural experiment was also conducted during the research. The first part of the study involved 8 sane people; 3 women; 5 men. The pseudo-patients phoned the hospital for an appointment, and arrived at the admissions complaining they could hear noises. They said the voices was unfamiliar, and was of the same sex as themselves, and was often unclear but it said the words "empty", "hollow" and "thud". The pseudo-p's were given a fake name and job (to protect future health and employment records) but all other details were true i.e. general ups and downs of life; relationships etc. After pseudo-patients were admitted to the ward they stopped displaying any symptoms of abnormal behaviour. Rosenhan noted the pseudo-patients were nervous, i.e. possible fear of being exposed as a fraud. The pseudo-p's took part in ward activities; spoke to patients and staff. Each pseudo-patient was told to get out by their own devices by convincing staff they were sane. Pseudo-patients spent time writing notes about their observations; was done secrety; but no one was bothered about their note taking and was done more openly.