Delusion
A doctor or psychiatrist may say that a delusion is false because it seems to be improbable or strange. Because psychiatrists do not always investigate a person's claims completely, they will sometimes wrongly diagnose a patient as delusional. This is called the Martha Mitchell effect, which was named after the wife of the attorney general in the Nixon administration. Martha Mitchell said that illegal activity was happening in the White House. At the time, people thought she was mentally ill. However, after the Watergate scandal, she was proved right.