In my research I gradually came to a conclusion that the phenomenon known today as the split personality is not fully understood. In my opinion every healthy and normal human has two personalities in their brain. The first one is the normal state of mind, which is directing our behaviour for 99% of our lives. The second mental state, which we can call “critical”, “alternative”, “collective”, or by some other names, gets activated only in the most critical moments of life, mostly when our physical survival in on the line.
In such critical moments (traffic accidents, natural disasters, terrorist attacks, combat situations) the “second personality” is activated. As a result, our usual “everyday” self has no control over our behaviours anymore, and our memory has no recollection of the subsequent events experienced while in the second state. This second, critical, or alternative personality has no ability to think rationally, to ask questions, or to say “no” to any suggestions or orders. This personality is accessible only when a person is in a deep hypnosis.
I suggest that for the healthy functioning of the brain these two personalities have to be fully isolated from each other. If the isolation between these two personalities is not strong (because of genetic predilections or overpowering stress), the isolation breaks down and the dramatic memories from the critical part of the brain enter into the first, “normal” personality. This is when the syndrome of split personality is manifested via sudden splitting headaches, nightmares, flashbacks, or unfounded and unreasonable phobias.
- For further reading you can see "Singing and Unconscious Thinking: Freud, Jung, Hypnosis and Split Personality" and "Unconscious Mind and Split Personality, or Why Did You Kill John Lennon?": excerpted from my 2011 book Why Do People Sing? Music in Human Evolution.