Friday, March 11, 2011

The right brain

In the last post I presented what is well known (and not particularly controversial) about the functions of the two brains.  In this post I will tell you what I think is happening.  Much of it is controversial. Most of it has some evidence, though I will not present the evidence.  If it resonates with you and you want to learn more, I encourage you to read the source materials for the blog, given in the first post.

First I will describe the right brain.  This is not arbitrary.  While neuroscience has previously referred to the left brain as the primary or dominant hemisphere, those labels are being called into question.  For example, in the book titled The Master and His Emissary, the master is the right brain, and the emissary is the left brain.  I hope you will agree after I describe this relation that this may be true.

The right brain sees the world as it is.  It perceives the world in concrete terms.  It doesn't interpret the world through any sort of symbolism or abstraction or rubrik.  It perceives the world in real time.  It doesn't form opinions about the world; it doesn't judge what it perceives.

The right brain sees the world as a flow in time.  One microsecond flows into the next, with no boundary or step.

The right brain perceives the world through all the senses all the time and integrates the senses into a single flow.  It doesn't focus on any one sense or any one sensation.

In the last post I said that the left brain only has access to the right visual field.  Further, it only has access to the center of the right side of the visual field.  I'll say more about that later.  I bring that up to contrast it to the visual access of the right brain.  The right brain has access to both the left and right sides of the visual field, and it has access to peripheral vision, which the left brain does not.  Thus, if the left brain is damaged, the right brain still has access to the full visual field, quite different from when the right brain is damaged.

The condition called asomatognosia illustrates the difference in perception.  A person with a right brain stroke, able to perceive only with the left brain, may be unable to perceive the left side of the body, depending on the extent of right brain injury.  If so, the person will often deny that the left side of the body even exists.  Such a person may complain that someone else is in bed with them, because that arm isn't theirs.  By contrast, a person with left brain stroke will generally not experience asomatognosia.  Such a person will have full body awareness, though sensation from and control of the right side of the body may be compromised.  The difference is that the right brain was aware of that side of the body all along and so has a memory of it.

The right brain sees the world in 3D.  This is aided by the availability of peripheral vision.  It knows how objects fit into 3-space and understands how they relate to one another.  It knows about depth and occlusion.  Note that this 3D view doesn't depend on binocular vision, which only works in a narrow range of near distances, so one-eyed people still see the world in 3D.  This 3D perception of the world comes from moving through the world and seeing how things change their relation as we move.

The right brain holds our true memories of the past.  These are sensual memories of the events that actually happened, integrating all the senses with the emotional context that accompanied them.  A recent 60 Minutes episode reported on "superior autobiographical memory", in which 6 people worldwide have been identified as able to recall every event in their lives.  It is likely that we all have some version of this kind of memory.  The issue is recall.

The right brain can extrapolate reality into the future.  This doesn't involve theorizing, it is just a continuous extension of current knowledge a few milliseconds into the future.  This is how a professional baseball player can hit a pitch when it is known that his eye-to-arm reaction time is much of the time it takes a baseball to travel from the pitcher's mound to the plate.  He doesn't "think" about hitting the ball so much as "seeing" it a bit early.  (And it's obviously not perfect.)  The professional baseball player also extrapolates the detailed body motions of the pitcher into an understanding of where and how fast the ball will arrive.  Personally, I've experienced catching something I knocked off a table, without any time to think about it.  These are all abilities of the right brain.

The right brain doesn't perceive boundaries.  In its 3D world view it doesn't see the boundaries between the objects we normally think of.  Moreover, it doesn't see a boundary between itself and the rest of the world.  It doesn't see itself as an active agent in the world.  It sees itself as continuously connected to all it perceives, including other people.

In the next post I will describe the left brain.  It is much different from the right brain, and I have hinted at some of the differences already.

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