In 1894, Daniel Hack Tuke presented a paper on "imperative ideas"−a term which primarily referred to obsessions and compulsions. The paper was published in the neurological journal Brain and, later, other neurologists responded to it.
In speaking of imperative ideas I refer to those cases in which a person would not be regarded as insane, although the mental trouble may be as distressing as it is in actual insanity....
With regard to the symptoms, they assume different forms. With some, the torment is that certain ideas or words arise with painful frequency and vividness. The thoughts which dominate the mind with morbid persistency are generally of an unusual and unwelcome character.... Then there are persons who invariably touch some object in passing it in the course of an accustomed walk (Délire du toucher), the antithesis of which is seen in the dread of touching certain objects at all, a true mysophobia....
One subdivision of imperative ideas, and a very striking one, is the insanity of doubt (Maladie du doute).... Then we have arithmomania, or the morbid desire to count without rhyme or reason, or to make interminable calculations.... Almost endless, however, are the terms which have been introduced to label the particular form which imperative ideas assume. Certain alienists [psychiatrists] simply revel in coining terms for every imperative idea which they have ever met with....
However allowable it may be for the sake of convenience thus to multiply terms, they must not distract our attention from the fundamental characteristics common to all imperative ideas. These are, their automatism, the overwhelming and recurring tendency to be haunted by a certain idea, to perform certain acts...without delusion..., and indeed with a consciousness of the utter uselessness and absurdity of dwelling upon these ideas, and of the things which are done....
We must, indeed, admit that we can hardly regard the individual who cannot control his thoughts in the way that he wishes to control and direct them as a person of perfectly sound mind; but no "last will and testament" would be set aside in this case, or on the ground that a testator had an invincible desire to touch certain objects, or an intense repugnance to touch certain articles of furniture.... Nor would such morbid habits of thought and association of ideas go far to sustain the plea of insanity and irresponsibility in a criminal trial....
[Here Tuke's paper gets more technical about the neurological basis of imperative ideas.]
...I believe that Dr. Jackson [Hughlings Jackson, who later responds to Tuke's article] has not in any of his writings referred specifically to imperative ideas other than as insane delusions.... [a position Tuke disputes]
Of the malady of doubt I have said that a troublesome, although slight degree of it, is not uncommon in perfectly sane people. It was only the other day that an officer of an asylum engaged in laboratory work, told me that not unfrequently after shutting the door the last thing at night and having no doubt that it was shut, he would return once or perhaps twice to satisfy himself that this was the case. In the same way I have known persons open an envelope in which they had placed a cheque and had exercised great care that the date and signature were correct, in order to satisfy themselves that they were so....
What strikes one forcibly in regard to most, if not all, imperative ideas is that between them and ordinary ideas the difference is one of degree, and that it is a most difficult thing to determine when the boundary line has been passed....
*Tuke also considered phobias to be "imperative ideas." For instance, he mentions that claustrophobia and agoraphobia are imperative ideas. In other words, he lumped OCD and phobias together.