http://www.washingtonsblog.com/2009/05/conspiracies-and-martha-mitchell-effect.html

John Mitchell was the Attorney-General during the Nixon administration.

His wife - Martha Mitchell - told her psychologist that top White House officials were engaged in illegal activities. Her psychologist labeled these claims as caused by mental illness.

Ultimately, however, the relevant facts of the Watergate scandal vindicated her.

In fact, psychologists have now given a label - the "Martha Mitchell Effect" - to "the process by which a psychiatrist, psychologist, or other mental health clinician mistakes the patient's perception of real events as delusional and misdiagnoses accordingly".

The authors of a paper on this phenomenon ( Bell, V., Halligan, P.W., Ellis, H.D. (2003) Beliefs About Delusions. The Psychologist, 6 (8), 418-422) conclude:

Sometimes, improbable reports are erroneously assumed to be symptoms of mental illness [due to a] failure or inability to verify whether the events have actually taken place, no matter how improbable intuitively they might appear to the busy clinician.

In other words, psychologists who haven't taken the time to examine for themselves the claims of their patients will tend to label as delusional anything which they "intuitively" feel is improbable.

Many psychologists - just as Martha Mitchell's - will tend to assume any claim of conspiracy is improbable. However, conspiracies are actually common occurences which are well-recognized by the law.

Psychologists are even more apt to label government conspiracies as improbable. However, as Martha Mitchell's psychologist learned, they do happen. Watergate, for example, was a conspiracy.

Psychologists who have attempted to label as delusional those who raise the possibility of government conspiracies do not have even a basic understanding of the Martha Mitchell Effect, or have not examined whether or not there is any factual basis for their patient's claims.

Obviously, some people are delusional, and see conspiracies where none exist. But it is equally true that when millions of scientists, military leaders, historians, legal scholars, intelligence officials and other rational people say the government is lying, psychologists who dismiss similar claims by their patients are falling prey to the Martha Mitchell Effect. They are too busy and/or arrogant to actually examine their assumptions as to whether or not the claims which feel improbable to them are true.