The recognition of Janet’s clinical observations and theoretical notions about trauma and dissociation indeed have received wide recognition, especially among those clinicians and researchers dealing with survivors of chronic traumatization. Of the many theorists of dissociation, Janet unquestionably presented the most detailed and articulate account of the connection between division of the personality or consciousness (i.e., dissociation) and hysteria (cf., Perry & Laurence, 1984; Putnam, 1989a; Van der Hart & Friedman, 1989; Van der Kolk & Van der Hart, 1989). Originally a philosopher and experimental psychologist, in his position as psychiatrist at the Salpêtrière Janet became the leading scientist in the study of hysteria.

His thesis for the doctorat ès-lettres, L’automatisme psychologique: Essai de psychologie expérimentale sur les formes inféreures de l’activité humaine (Janet, 1889), can be regarded as history’s most important work on dissociation. In his Editorial of the American Journal of Psychiatry celebrating its centenary, John C. Nemiah (1989) wrote:

The recent festivities celebrating the bicentennial of the French Revolution have overshadowed the remembrance of another occurrence in French history that, from a scientific point of view at least, is perhaps of equal magnitude. (p. 1527)

Janet considered hysteria to be “an illness of the personal synthesis” (Janet, 1907, p. 332). By this, he meant “a form of mental depression [i.e., lowered integrative capacity] characterized by the retraction of the field of consciousness and a tendency to the dissociation and emancipation of the systems of ideas and functions that constitute personality” (Janet, 1907, p. 332). Janet’s definition of hysteria makes it clear that he distinguished between retraction of the field of consciousness and dissociation. For him, retraction of consciousness merely implied that individuals have “in their conscious thought a very limited number of facts” (Janet, 1907, p. 307). Nowadays many students of dissociation subsume phenomena related to retraction of the field of consciousness, such as absorption and imaginative involvement, under the label of dissociation. Although Janet was not always explicit about this, he thought that these dissociative “systems of ideas and functions” had their own sense of self, as well as their own range of affect and behaviour.

Janet acknowledged a role for constitutional vulnerability in illnesses of personal synthesis, but he regarded physical illness, exhaustion, and, especially, the vehement emotions inherent in traumatic experiences as being the primary causes of this integrative failure (Janet, 1889, 1909, 1911). In keeping with this formulation, the most obvious of these dissociative systems contain traumatic memories, which he originally described as primary idées fixes (Janet, 1894b, 1898). These systems consisted of “psychological and physiological phenomena, of images and movements of a multiform character” (Janet, 1919/25, p. 597). When these systems are reactivated, patients are “continuing the action, or rather the attempt at action, which began when the [trauma] happened; and they exhaust themselves in these everlasting recommencements” (Janet, 1919/25, p. 663).

Janet actually observed that dissociative patients alternate between experiencing too little and experiencing too much of their trauma:

Two apparently contrasting phenomena constitute a syndrome: They are linked together, and the illness consists of two simultaneous things: 1) the inability of the subject to consciously and voluntarily recall the memories, and 2) the automatic, irresistible and inopportune reproduction of the same memories. (Janet, 1904/11, p. 528)

Janet (1889, 1904, 1928) observed that traumatic memories/fixed ideas not only may alternate with the habitual personality, but also may intrude upon it, especially when the individual encounters salient reminders of the trauma.

Janet also drew upon traumatic memories to explain the distinction between the mental stigmata and the mental accidents that characterize hysteria (Janet, 1893, 1894a, 1907, 1911; cf., Nijenhuis & Van der Hart, 1999). He did not make any distinction between dissociation of the mind and dissociation of the body in mental stigmata and accidents. And, like his contemporaries, he regarded symptoms pertaining to movements and sensations as dissociative in nature. The mental stigmata are negative dissociative symptoms that reflect functional losses, such as losses of memory (amnesia), sensation (anesthesia), and motor control (e.g., paralysis). The mental accidents are positive dissociative symptoms that involve acute, often transient intrusions, such as additional sensations (e.g., pain), movements (e.g., tics) and perceptions, up to the extremes of complete interruptions of the habitual part of the personality. These complete interruptions were due to a different part of the patient’s personality that was completely immersed in re-experiencing trauma.

Related to primary idées fixes, i.e., traumatic memories, were secondary idées fixes, i.e., fixed ideas not based on actual events, but nevertheless related to them, such as fantasies or dreams. For example, a patient might develop hallucinations of being in hell secondarily related to an extreme sense of guilt during or following a traumatic experience. Such dissociative episodes were called hysterical psychosis, more recently relabeled as (reactive) dissociative psychosis (Van der Hart, Witztum & Friedman, 1993).

According to Janet, the more an individual is traumatized, the greater is the fragmentation of that individual’s personality: “[Traumas] produce their disintegrative effects in proportion to their intensity, duration, and repetition” (Janet, 1909, p. 1556). Janet regarded multiple personality disorder as the most complex form of dissociation and he noted the differences in character, intellectual functioning, and memory among dissociative parts of the personality (Janet, 1907). He observed that certain dissociative parts had access only to their own past experience, while other parts could access a more complete range of the individual’s experience. Dissociative parts could be present side by side and/or alternate with each other.

In general, Janet believed that dissociation pertains to the division of the personality into dissociative “systems of ideas and functions,” each with its own sense of self. For Janet, the division of the personality into dissociative “systems of ideas and functions” was not restricted to DID, but occurred in many forms of hysteria. It has been suggested that in his later life Janet became dismissive of dissociation and DID as psychological concepts (Hacking, 1995). As testified in one of Janet’s later books, published a year before his death (Janet, 1946), this belief is unfounded. His conclusion on double and multiple personalities in this treatise leaves no space for misunderstanding the value he attached to the phenomenon of dissociation, in even a wider range of mental disorders:

These divisions of the personality offer us a good example of dissociations which can be formed in the mind when the laboriously constructed syntheses are destroyed. The personal unity, identity, and initiative are not primitive characteristics of psychological life. They are incomplete results acquired with difficulty after long work, and they remain very fragile. All constructions built by the work of thought belong to the same genre: Scientific ideas, beliefs, memories, languages can be dissociated in the same way, and the end of illnesses of the mind is the dissociation of tendencies as one observes in the most profound insanities. (p. 146)

Janet (1898, 1911, 1919/25) developed a phase-oriented three-stage treatment approach avant la lettre:

•  stabilization and symptom reduction, aimed at raising the patient’s integrative capacity;
• treatment of traumatic memories, aimed at the resolution or completion of the unfinished mental and behavioral actions inherent in these traumatic memories; 
• personality (re)integration and rehabilitation, i.e., the resolution of dissociation of the personality and fostering of further personality development (Van der Hart, Brown & Van der Kolk, 1989).

Phase-oriented treatment of patients with a history of chronic traumatization is currently considered to be the standard of care (e.g., Boon & Van der Hart, 2003; Brown, Scheflin, & Hammond, 1998; Courtois, 1999; Herman, 1992; Steele, Van der Hart, & Nijenhuis, 2005; Van der Hart, Nijenhuis, & Steele, 2006).

Onno Van der Hart and Martin Dorahy