On Wednesday, Professor Peterson introduced the concept that our main "conscious" is composed of at least two separate ones. When we got to the example where the subjects' left hand acted on its own, I thought to myself, "How can his hand do things without him realizing it?" and realized the question sounded exactly the same as one I'd asked only about 2 weeks prior: "How could Mr. B-2 have done things for two years without Mr. A realizing it?"
Mr. A is a friend of mine who has something like MPD, and he has alters I shall refer to as B-1 and B-2. Mr. A's MPD differs from the book's description in that while his alters can take over his body, they prefer not to and typically stay within a mental world. Mr. A locked his alters away for a few years, and during those years Mr. B-2 was still actively building things within the mental world while Mr. B-1 was "watching" Mr. A and trying to contact him.
I had assumed that the moment the alters were ignored, they went into a sort of stasis. To hear that they acted on their own seemed impossible to me; just as impossible as the rouge left hand, albeit without any physical evidence. After Wednesday, I can believe that our perceived "conscious" may be composed of multiple ones in a collective.
Perhaps as a result of trauma, parts of the brain start overreacting to everything out of fear, and the rest of the mind habituates itself and starts ignoring the overreactions (a natural attempt of isolating a seizure by cutting the corpus callosum, if you will). Due to the temporary, one-way nature of habituation, this would explain how Mr. B-1 was able to see Mr. A while Mr. A was not able to perceive him until years later
On a sidenote, I don't have space to ponder the following, but I found it interesting and relevant to the concept of a collective conscious: Ants get smarter in groups (#2). I have to wonder if this is the same idea, but with the conscious distributed among millions of bodies.