Chapter 8. Dissociation and Neuroscience (1) the “Hidden Observer” (2)

In this experiment, it was not particularly DID patients who were chosen to be the subject. Hilgard’s experiment poses us a question about whether any of us can have a potential condition of DID, so long as they are hypnotized and reveal the existence of their “hidden observers”. Actually this was the question that came up to my mind when I first read about this experiment.
I also have the same question when I see some scenes of stage hypnosis. Stage hypnosis is performed in front of an audience for the purposes of education or entertainment. Typically an age regression is induced and the subject becomes a small child and speak and act as such. If a portion of the population is susceptible enough to be hypnotized to the level where they demonstrate the existence of an independent observer or childhood personality, does it mean that they potentially have DID or DID-like condition?
These questions are relevant, but we do not seem to have any clear-cut answer. What is clear is that not everyone gets hypnotized as Hilgard’s experiment reports. Only a small percentage of us get hypnotized to a level where age regression can be induced. Those who demonstrate age regression can only be rare cases, or the stage hypnosis itself might really be a “staged” one.
However, there is another possibility: those who shows hidden observers or age regression might happen to be patients with DID. It is because DID in the general positions and highly hypnotizable people are comparable in number. Highly hypnotizable population is reported to be around 10~15 % (Raz, et al. 2007) whereas the incident of DID among general population is reported to be around 2~4 % (Dell, 2009).
Raz,A. et al.（2007）Suggestion overrides the Stroop effect in highly hypnotizable individuals Consciousness and Cognition 16: 331-338
Dell, P. (2009) OUTlINE The Long Struggle to Diagnose Multiple Personality Disorder: Partial MPD. in DISSOCIATION AND THE DISSOCIATIVE DISORDERS. DSM-V AND BEYOND Edited by Paul F. Dell, and John A. O'Neil. Routledge.
Neural Network Model
Instead of asking whether we have homunculus in our head or not, modern neuroscience asks if there are neural networks in which different identities can reside. Human brain consists of a huge system of neural networks. There is no rule that there is only one identity that the neural networks can hold, taking into consideration that animals with neural networks of much smaller sizes seem to have their own minds.
Considering DID from a neural network point of view gives us a tangible idea about what we are dealing with. Imagine that there are two identities that are based on two different locations of brain. This can be demonstrated on fMRI, as when personality A is active, location a might show elevated activities whereas B is active, location b can show high activities on the imaging. However, in fact, neural networks that different personalities are based on seem to be so closely enmeshed with each other, that no discernable activity patterns of separate identities are demonstrated on the fMRI.