Second, the term "personality" is used to refer to "characteristic patterns of thoughts, feelings, moods, and behaviors of the whole individual", while for a patient with DID, the switches between identities and behavior patterns is the personality. It is for this reason the DSM-IV-TR referred to "distinct identities or personality states" instead of personalities. The diagnostic criteria also changed to indicate that while the patient may name and personalize alters, they lack independent, objective existence. The changes also included the addition of amnesia as a symptom, which was not included in the DSM-III-R because despite being a core symptom of the condition, patients may experience "amnesia for the amnesia" and fail to report it. Amnesia was replaced when it became clear that the risk of false negative diagnoses was low because amnesia was central to DID.The ICD-10 places the diagnosis in the category of "dissociative disorders", within the subcategory of "other dissociative (conversion) disorders", but continues to list the condition as multiple personality disorder.The DSM-IV-TR criteria for DID have been criticized for failing to capture the clinical complexity of DID, lacking usefulness in diagnosing individuals with DID (for instance, by focusing on the two least frequent and most subtle symptoms of DID) producing a high rate of false negatives and an excessive number of DDNOS diagnoses, for excluding possession (seen as a cross-cultural form of DID), and for including only two "core" symptoms of DID (amnesia and self-alteration) while failing to discuss hallucinations, trance-like states, somatoform, depersonalization, and derealization symptoms.
Vivet was the subject of countless medical papers and became the most studied case of dissociation in the 19th century. Between 1880 and 1920, various international medical conferences devoted time to sessions on dissociation. It was in this climate that Jean-Martin Charcot introduced his ideas of the impact of nervous shocks as a cause for a variety of neurological conditions. One of Charcots students, Pierre Janet, took these ideas and went on to develop his own theories of dissociation. One of the first individuals diagnosed with multiple personalities to be scientifically studied was Clara Norton Fowler, under the pseudonym Christine Beauchamp; American neurologist Morton Prince studied Fowler between 1898 and 1904, describing her case study in his 1906 monograph, Dissociation of a Personality. 20th century
In the early 20th century, interest in dissociation and multiple personalities waned for several reasons. After Charcots death in 1893, many of his so-called hysterical patients were exposed as frauds, and Janets association with Charcot tarnished his theories of dissociation. Sigmund Freud recanted his earlier emphasis on dissociation and childhood trauma.In 1908, Eugen Bleuler introduced the term "schizophrenia" to represent a revised disease concept for Emil Kraepelins dementia praecox. Whereas Kraepelins natural disease entity was anchored in the metaphor of progressive deterioration and mental weakness and defect, Bleuler offered a reinterpretation based on dissociation or "splitting" (Spaltung) and widely broadened the inclusion criteria for the diagnosis.