Below is an excerpt from psychologist John Kihlstrom’s ¬≠2005 review article on dissociative disorders where he talks about the sudden ‘epidemic’ of multiple personality disorder, now know as DID, in the 1960s and 70s.
Dissociative Identity Disorder or DID is a diagnosis that describes where someone manifests various personalities, often of a diverse range of people – from children to adults of either sex.
It is controversial partly because diagnoses seemed to massively increase when two famous films on the disorder were popular.
Kihlstrom makes the interesting point that the increase in the number of people diagnosed with the disorder was also matched by an increase in the number of personalities each person seemed to have.
An interesting feature of the DID “epidemic” is an increase not just in the number of cases but also in the number of alter egos reported per case. In the classic literature, the vast majority of cases were of dual personality (Sutcliffe & Jones 1962, Taylor & Martin 1944). By contrast, most of the new cases compiled by Greaves (1980) presented at least three personalities; in two other series, the average number of alter egos was more than 13 (Kluft 1984, Putnam et al. 1986).
As Kenny (1986) noted, it was almost as if there were some kind of contest to determine who could have (or be) the patient with the most alter egos. The famous Eve, of course, appeared to have three personalities (Osgood & Luria 1954, Thigpen & Cleckley 1954). But when popular and professional interest in MPD was stimulated by the case of Sibyl, who was reported to possess 16 different personalities (Schreiber 1973), Eve replied with her own account of her illness, eventually claiming 22 (Sizemore & Huber 1988).
Despite the almost-infinite number of possible synaptic connections in the brain, one might say that the mind simply is not big enough to hold so many personalities. The proliferation of alter egos within cases, as well as the proliferation of cases, has been one of the factors leading to skepticism about the disorder itself.
In general, dissociative disorders are where one part of consciousness seems to be ‘split off’ or inaccessible to another.
For example, psychogenic amnesia or conversion disorder (‘hysteria’) are more common examples and hypnosis seems to reliably induce the phenomena in some people.
These are still some of the most mysterious processes in psychology and are fraught with controversy, particularly as they’re often linked to repressed memories from abuse or trauma.
This is one of the more difficult areas to study scientifically because it largely relies on self-report, and Kihlstrom notes there is still no convincing evidence that trauma or abuse leads to amnesia for the event.
Link to PubMed abstract of Kihlstrom’s review.
Link to full-text of pre-print.
Mind Hacks 
I think is just a matter of degrees. The mind and the ego aren’t a whole in themselves. Every spiritual path states that our mind is scattered without a unifying center. A quote from Aldous Huxley: “Since human craving can never be satisfied except by the unitive knowledge of God and since the mind-body is capable of an enormous variety of experiences, we are free to identify ourselves with an almost infinite number of possible objects – with the pleasures of gluttony, for example, or intemperance, or sensuality; with money, power or fame; with our family, regarded as a possession or actually an extension and projection of our own selfness; with our goods and chattels, our hobbies, our collections; with our artistic or scientific talents; with same favourite branch of knowledge, some fascinating “special subject”; with our professions, our political parties, our churches; with our pains and illnesses; with our memories of success or misfortune, our hopes, fears and schemes for the future; and finally with the eternal Reality within which and by which all the rest has its being. And we are free, of course, to identify ourselves with more than one of these things simultaneously or in succession. Hence the quite astonishingly improbable combination of traits making up a complex personality. Thus a man can be at once the craftiest of politicians and the dupe of his own verbiage, can have a passion for brandy and money, and an equal passion for the poetry of George Meredith and under-age girls and his mother, for horse-racing and detective stories and the good of his country – the whole accompanied by a sneaking fear of hell-fire, a hatred of Spinoza and an unblemished record for Sunday church-going.”
Similar phenomena ocurred when a huge increase in those exhibiting what was referred to as being spiritually “possessed” (by the devil [sic]) and subsequent exorcism rites (by religious authorities
who were quite enthusiastic about reporting such
incidents to underscore the existence of the “Devil”) in the aftermath of the release of the movie “The Exorcist” in 1973.
Hi msavoy,
Thanks for that, it’s just reminded me of a classic paper on The Exorcist and ‘cinematic neurosis’. A post is forthcoming…