• Alec
    45
    The following is an argument for an odd conclusion: That we are not merely one mind in one body, but one of two minds in one body. Normally people tend to think of themselves as being alone, but it seems as though findings in empirical science suggest that there is more to the brain than we would like to think. Here's a helpful video that illustrates what I am talking about:



    People who have had their brains split in two (their corpus callosum severed) have been known to exhibit some very strange behaviour. Under certain experimental situations where split-brain subjects are shown certain images on the left side of their vision, they do not report ever seeing anything in their visual field, and yet their hands may be able to draw out what they claim to not see. In other situations, a person may also be shown a funny image in their peripheral vision, causing them to laugh but not be able to explain why they are laughing.

    In addition, in more extreme cases, people who suffer from alien hand syndrome may even find themselves fighthing with themselves, or at least, their own hands. They may reach for objects that they didn't consciously want to reach out for and they may have to restrain themselves in such cases. In these situations the people who are afflicted are also known to have had severed or at least damaged corpus callosums as well.

    So what are we to make of this? Let us consider some of the possible explanations that are available:

    One Mind, Scattered Experiences: The first suggestion states that there is only one mind, but that the contents of their consciousness are scattered and disunified. This means that a single conscious subject will find themselves at any time to be having an experience of one set of experiences that feels alone while having another that similarly feels that way as well, despite them being had together. In the experiments above, subjects may see red in their entire visual field, as well as green in their entire visual field, or they may find themselves wanting and not wanting to reach for an object simultaneously. This approach pushes ahead with the One Mind view even in the situations above. The problem with this view though is that it sounds impossible, as the requires that one conscious subject has an incompatible set of experiences. What would it possibly be like to see a red patch and a green patch in the exact same region of your vision for instance? Or two experiences alongside one another in one experience when both feel like they are had alone? It would be like imagining a square circle, a married bachelor, or (literally in this case) a red-green ball, which is to say it is an impossible experience.

    One Mind, One Hemisphere: There have been explanations which try to limit the mind to one hemisphere in the brain. It can be either of the hemispheres but generally people seem to favour the left hemisphere as that is the hemisphere that is capable of speech. This view, unlike the former, is not strictly impossible as it gives a coherent view of experience for the conscious subject by taking only one side of the story in each of those cases as the one that is had by the conscious mind. However this proposal seems problematic as well, as both hemispheres are equally functional post severing of the corpus callosum. Thus it doesn't seem as though we should say that one of them suddenly loses it's mind. Even if we are forced to say which one is which, it doesn't seem like we have any means for favouring one hemisphere over the other either. Although both hemispheres serve different functions, they are both equally complicated in their own right. So given the similar complexity in both hemispheres it is hard to believe that only one retains a mind while the other does not.

    One Mind that splits into Two Minds under certain conditions: According to this option, there is one mind that operates in normal day to day activities, but splits into two minds under certain situations such as the ones mentioned above. This concedes that there are two minds involved in the situations above, but retains the view that there is one mind in normal everyday situations. I am not a fan of this view either since it seems a bit much to say that a new mind is literally created when a split brain subject is subject to certain situations where two minds are necessary, only to destroy that mind when that situation passes. In addition, such a proposal does sound contrived to me as well.

    Two Minds: At last, we are left with the option that I have been trying to lead to all this time. The proposal here is that there are two minds at play within the split-brain individual, each of which represent one hemisphere in the brain. One is able to see the things on the left side of their vision while the other sees nothing there and they react accordingly. One may want to reach out for an object, while another may disagree with that desire. The notion that there are two minds in contrast, though strange, is not inherently implausible. It allows us to make sense of the split brain cases without creating impossible experiences, privileging one hemisphere, or making the dual minds a temporary case. As far as I see it this seems to be the commonly accepted view, given that other explanations that try to endorse one mind are known to end up with serious problems as mentioned above.

    Of course, this story is usually intended to be reserved for people who have severed corpus callosums to begin with, and not regular people like you or me. As some may argue, we would normally have one mind, but when we have our brains split, we acquire a new mind in the process. Although one may say that, I don't believe that this duality is just a unique feature for severed brains alone.

    In a way, it is hard for me to believe that the act of cutting the corpus callosum would lead to such a radical change as an addition of a new mind. For consider a ship of theseus style case where one tries to sever the corpus callosum bit by bit. When does the addition occur; is there a step in the process that determines when one mind becomes two? What happens to the old mind? Is it going to cease to exist or does it become one of the hemispheres? Given these considerations, it seems easier to say that we have two minds all of the time and sounds alot more simpler by comparison.

    So this leaves us with the final option, and the one that I have been trying to argue for: That the brain has two minds all along! There is no conceptual problem in envisioning two minds in one body, and the worst problem seems to be in explaining how split brain individuals function normally most of the time despite their severed corpus callosum. And although I do not deny the strangeness of this view, it isn't all that surprising when we understand how the brain operates. In fact a deeper understanding of the brain shows that this idea isn't so far fetched at all. As neuroscientists study the brain more, they have discovered that both hemispheres are quite autonomous, capable of processing information and making decisions independently of the other. There have been reported cases where patients have had entire hemispheres removed from their brain and yet they are still capable of functioning normally despite the missing half. This has been seen in both the removal of the left and the right hemisphere and seems to suggest that each half can alone be sufficient for a conscious mind.

    So it seems that we are not really alone, even when we are. There may be a second "you" in your body having essentially the same experiences (with some exceptions of course) as you do.

    Questions? Objections? Thoughts? Feel free to leave them here.
  • wellwisher
    163
    The split in the two hemispheres appears to correlate to differential versus integral thought processing and thinking. Either method of thought processing can orientate one to reality. Like in math, differentiation finds the slope of a curve at a given point, while integration finds the area under a curve from point A to B.

    Differentiation sees uniqueness and detail, whereas integration sees commonality. For example, if a Westerner was to travel to the Orient, the integration factor would make it seem like everyone looks similar; commonality. If we stay long enough, we would start to differentiate more and more subtle differences.

    Normally both operations occur in the brain, with both operations self standing. Differentiation is more conscious than integration in most people. This could be due to the needs of language, as you pointed out. One can see the process of differentiation in science, which generates and collect data faster; differential, than it processes or integrates it. Differential is 2-D whereas integral is 3-D.

    Relative to emotions, love and hate have a connection to integral and differential thinking, respectively. Love integrates people with each other. Love seeks commonality; family and friends. Hate is more differential since it isolates and differentiates. Our emotions cross the boundaries. Religions based on love attempt to induce integral thinking; 3-D. Racism is a composite that differentiate a subset of all people, and then integrates that subset, into an average.
  • Alec
    45
    Making this post partly as a bump for discussion, but really I just want to point to a nice short video I've just found that illustrates my point:



    For those of you who are worried about the text and all that, then hopefully this will help set things up.
  • BC
    13.1k
    If the halves of the brain were never connected by the cerebral commissure, then two "persons" might develop (from birth forward). I don't know whether this has ever happened and been observed. Severing the cerebral commissure in someone who has already developed an intellect and personality (using both hemispheres of the brain) results not in two persons, but two now uncoordinated hemispheres. I (quite literally) can not imagine what that would be like.

    The topic is fascinating. Some very radical brain surgeries are still done to control refractory epilepsy, such as severing connections to selected areas of one hemisphere where seizures arise. These are often close to the language centers, so prior to doing this sort of surgery, a preliminary test is done on the exposed brain (and conscious patient) to map out exactly what features will be lost if the surgery is performed as planned. Sometimes it is found that too much language facility will be lost -- and then the surgery is not worth doing, even for refractory epilepsy.

    It should be noted that severe epilepsy that doesn't respond to medication (is refractory) is quite destructive--so drastic measures may be worth trying.
  • Alec
    45
    If the halves of the brain were never connected by the cerebral commissure, then two "persons" might develop (from birth forward). I don't know whether this has ever happened and been observed.Bitter Crank

    Apparently in some cases, the infant brains will create new connections between the two hemispheres as they develop, but I'm not sure what will happen in cases where that does not happen. I wonder if something akin to a conjoined twin scenario could occur as a result of being born with a completely separated brain.

    Severing the cerebral commissure in someone who has already developed an intellect and personality (using both hemispheres of the brain) results not in two persons, but two now uncoordinated hemispheres. I (quite literally) can not imagine what that would be like.Bitter Crank

    If by "persons" you are referring to conscious minds, then I would say otherwise (or rather I would say that brains in general would possess two "persons" or minds whether split or not). Like you I would not be able to imagine what it is like to have a single mind in the split brain cases above, which I would take to count against that scenario's possibility.
  • BC
    13.1k
    I am loath to admit 2 minds in one brain. Admitting two separate minds in one body gets out of hand very quickly.

    Interestingly, people can live without the right hemisphere of their brain. On a few occasions, the hemisphere has been removed because of disease. I'm pretty sure nobody who had this done counted it as an improvement, but they didn't drop dead from it, either. I suppose they could live without a right hemisphere (not in addition to losing the right hemisphere, but as an alternative -- though I have met people who appear to be without any brains whatsoever). If the left hemisphere was removed, they wouldn't be able to tell us much about what it was like.

    The two hemispheres are not duplicates of each other, but are rather complimentary. Different specialties are allocated to opposite hemispheres -- such as language being in the left hemisphere, while rhythm is a specialty of the right brain. The left brain thinks more in a sequential, linear fashion, while the right brain is given to more of a gestalt, a-linear style. On the other hand, each hemisphere processes left/right body sensory information (sight, hearing, touch, proprioception, smell, taste, etc.).

    There is an interesting book by a brain anatomist, Stroke of Genius by Jill Bolte Taylor. She suffered a severe stroke; the book is about her recovery and about brain function and anatomy. Easy read, very interesting. Search YouTube for Jill Bolte Taylor and you can watch her TED talk -- summarizes everything in the book.
  • Alec
    45
    I am loath to admit 2 minds in one brain. Admitting two separate minds in one body gets out of hand very quickly.Bitter Crank

    I can understand the resistance, but that seems like the only sensible option IMO. Most of the crazy situations you'd expect come from such a scenario would come when both parts of the brain are incapable of communicating with each other. So for most normal people (without split brains), you don't have to worry about fighting with yourself.

    Interestingly, people can live without the right hemisphere of their brain. On a few occasions, the hemisphere has been removed because of disease. I'm pretty sure nobody who had this done counted it as an improvement, but they didn't drop dead from it, either. I suppose they could live without a right hemisphere (not in addition to losing the right hemisphere, but as an alternative -- though I have met people who appear to be without any brains whatsoever). If the left hemisphere was removed, they wouldn't be able to tell us much about what it was like.

    The two hemispheres are not duplicates of each other, but are rather complimentary. Different specialties are allocated to opposite hemispheres -- such as language being in the left hemisphere, while rhythm is a specialty of the right brain. The left brain thinks more in a sequential, linear fashion, while the right brain is given to more of a gestalt, a-linear style. On the other hand, each hemisphere processes left/right body sensory information (sight, hearing, touch, proprioception, smell, taste, etc.).
    Bitter Crank

    I believe there are also cases where people have lived without their left hemisphere as well. Most people who would go through such an operation won't function to the same degree as normal people, for obvious reasons, but I find it fascinating that they can function at all in any capacity. Some may still even exhibit signs of above average intelligence, and in one purported case, one subject had managed to go to graduate school despite the lack of one hemisphere. It's interesting stuff.

    My takeaway from it is that the individual hemispheres, though they may coordinate with each other, are capable of operating independently when need be, which I take to be a sign of their autonomy. The corpus callosum seems to serve mainly as a communication channel for the two of them rather than a mental glue that makes them one.

    There is an interesting book by a brain anatomist, Stroke of Genius by Jill Bolte Taylor. She suffered a severe stroke; the book is about her recovery and about brain function and anatomy. Easy read, very interesting. Search YouTube for Jill Bolte Taylor and you can watch her TED talk -- summarizes everything in the book.Bitter Crank

    Thanks, I'll check it out.
  • BC
    13.1k
    individual hemispheres, though they may coordinate with each other, are capable of operating independently when need beAlec

    Yes, but we have to put that into evolutionary context. 99.999% of the time, brain hemispheres have never had to operate independently (at least in primates) and the opportunity to do so came about only in the past few decades. Otherwise, any injury or disease which destroyed a hemisphere would have led to death. Normal primates do not have brains with independent hemispheres.

    Now, some animals -- certain dolphins, if I remember correctly, are able to put 1/2 of their brain to sleep while the other half pays attention. These dolphins live in non-ocean environments where sleeping in both hemispheres at the same time would lead to disaster. That is a unique evolutionary adaptation not available to other species.

    There are lots of very interesting neurological cases. Henry Molaison for instance. He had radical surgical for epilepsy in 1953 or 1957. He recovered--but without the capacity to form new memories. For the rest of his life (he lived a normal life span, and died just a few years ago) his supply of permanent memories were what he had accumulated by age 21 (+/-). He spent the rest of his life being looked after. He could read, but he couldn't remember what he had read. (I believe he had some procedural memory -- he could find his way to the washroom and back, for instance (If I remember correctly, he said ironically). And remarkably, his performance improved slowly over time on a particular test (where the subject copies an object by looking at a mirror image of it). This type of procedural memory had not been previously observed. He could cooperate in research (which is what he did much of his life) but he couldn't remember anything about the researchers with whom he worked--once they left the room for a minute or two. When they came back into the room, it was like he was meeting them for the first time.

    Books by neurologist Oliver Sacks are collections of these kinds of situations. (Maybe you know of Sacks?) If not he wrote fascinating books about brain dysfunction like "The Man Who Mistook His Wife for a Hat". Sacks himself was 'face blind' -- he could not remember faces. He also died just recently.
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