A physician in charge of a well-known asylum for the care of the insane recently said: There is one infallible test either for the approach or the presence of lunacy. If the person whose case is being examined is seen to make no use of his thumb, if he lets it stand out a right angles from the hand, and employs it neither in salutation, writing, nor any manual exercise, you may set it down as a fact that that person’s mental balance is gone. He or she may converse intelligibly, may in every respect be guarding the secret of a mind diseased with the utmost care and cunning, but the tell-tale thumb will infallibly betray the lurking madness which is concealed behind a plausible demeanor.
So, do you think this is in the DSM-IV?