David raised the subject of 'schizophrenia', which is coherent example of something modern day psychiatry views as being purely due to brain malfunctioning, a viewpoint based on hallucinations not matching our physical world, which according to the materialist's paradigm means evidence of 100% false delusions...
however ....
..... as indicated in the dream telepathy controlled lab experiments (and in fact any successful telepathy experiment), it doesn't matter if such hallucinations only slightly match our physical reality, if these are shared with another mind to any degree beyond statistical chance measurement, we have to seriously consider that *some* 'schizophrenic' hallucinations may be 'virtually real' and not necessarily a disease generated solely by the physical brain.
The controversial subject of 'possession'
To confuse matters, when most people think of 'possession' today, they imagine a horror film scene with Christians grasping crucifixes in fear, holy water splashed everywhere, praying frantically for satan to be exorcised from some crazed violent person, usually with demented organ music in the background in some dimly lit location....... one almost expects comedian Dave Allen to emerge from the possessed body with a funniest of punch lines
So let's put those religious, film and comic images to one side and ask a very serious question .....
*If* telepathy exists (and the evidence for weak on average telepathy is compelling unless one demands a constantly repetitive effect) ...... can one mind adversely affect another? The answer is most probably yes.
Are there logical reasons why telepathy would be commonly weak or borderline effect in most people?
Yes is the answer. Debunkers in the past have taken pot-shots at telepathy for not evolving to be strong evolutionary advantage ... this is fallacious argument...... because perfect 100% telepathy would lead to a loss of sense of individuality and individuality is clearly a major component of 'self' in consciousness, a sense of self essential for competitive survival on earth.
This could be one (along with several other) good reasons why the physical brain evolved to filter out telepathy and why it is found commonly weak or erratic in most parapsychology trials.
Psychiatrists may counter that brain damage/changes in cases of schizophrenia are the only cause, however with the hypothesis the brain is a filter of a creative external consciousness, any disruption of the brain filtering is arguably likely to increase hallucination when the mind is detached from the physical senses and from any other 'shared' sense of reality. Nor can schizophrenia be solely predetermined from birth, as there are cases of only one of a pair of identical twins being affected by the condition.
Reincarnation?
If the physical brain evolved to shut down telepathy for several good reasons, we also have to consider that telepathy may be a mechanism closely linked to accessing our own private memories that are not necessarily stored within the brain (until science proves otherwise). In fact we could speculate much further and suggest consciousness is split by incarnating into a physical brain, the physical brain shuts of past memory (and the memories of others) as unwanted intrusions and a new individual consciousness splits off from a prior one i.e. Reincarnation (but not quite in the eastern religious sense). This might also explain why the often claimed 'collective unconscious' is unconscious and not consciously accessed while functioning through a brain