bi camerail mind

https://en.m.wikipedia.org/wiki/Bicameralism_(psychology)

I heard of this in Graham Hancock book.  That people even 3000 years ago experienced life differently. We have mythology and stories of people hearing Akashavaani, words from the sky. basically in key moments in their life, they experienced some voice - which they interpreted as god, telling them what to do or told a prophecy or what ever. This is in Hindu mythology, Greek , Roman and almost every where else.

The theory is that we have evoled from this and even tho hardware of our brain remains the same, our software has changed radically as we dont hear these voiced anymore.

That is an interesting theory, which has been debunked.

But wait, I think the hearing voices is accurate but the interpretation that it doesnot happen any more is wrong.The hardware or software hasn't changed but we are just not using that voice generating part of our brain or atleast not admitting to hearing those voices.

What he is talking about is detaching from the part of our brain we call as self or ego and paying attention to different parts of our brain like intuition. Basically it is possible to detach from the sense of self,  it is possible to exprience different aspects of our subconscious which is hidden in normal people as a completly different person, like Ramanujan experiencing Goddess Kali, who solved Mathematical equations for him. Modern society calls this schezophernia, thats disfunctionally seeeing the inner working of subconscious. Some spritual people even today meet their spritual guides, see fairies get guidence from them, these are all after all aspects of their own brain,but not identified as self by the brain software. They are however not disfunctional but normal functioning people. The other aspects can also be experienced using Hallucinogens like LSD etc which can cause visions and trips. 

An easyish experiment with detaching from ego is doing seance, dowsing etc. you are moving the coin or the stick, but the part that is moving is detached from ego n operated by some other part of the  brain. It feels like some other entity is moving our hand. We dont own that movement. 

Slightly harder is auto writing or auto drawing. Allowing our hand to draw what it wants, You have no idea where it is going or what is going to happen next but ur hand pics up colours an draws. 

its wonderful to experience that your body is very capable of acting without ego.

In fact the book 'drawing with the right side of the brain ' says that it is imperative that u detach from ego to do art, may be not to this extent but you really want the critical and restless judging part of your brain to give up control. 

This not ego/self part of the brain software is also called intution, when you do a lot of meditation and get in touch with your intuition,  you expereince this - someone telling you what to do phenomenon. Its not blatant and dramatic like voice from the sky, its just another thought but it feels slightly different, u feel like someone else is talking to you. You can follow it and have a great adventure. Take this road, take this bus, get off now! ! you have no idea where it is leading you :) 

Yawning and stretching is a bit like that, our discomfort leading us on to an action which is required. Auto movements during meditation is exaggerated version of that. Do you know that yoga was actually invented like that. The body of the rishis went into these poses automatically as they medidated. My auto movements during meditation some times lead to mudras and to accupressure points.
So I am saying that Bi camerial brain may have been a very simplistic theory but it strayed quite close to the truth.