It was conducted by a neurobiologist, Roger Sperry. It was found that cutting the synapse between the two hemispheres (left and right) reduced the onset of seizures in epilepsy patients. A study was conducted to observe what consiquences if any having a "split brain" would entail. In a nutshell, what they found was that, in a patient, when presented with an object to his right eye, he was not able to draw it with his right hand, until his left eye had explicitly seen it first, and vice versa. Also, when asked to draw an object he visualized, he could only draw it with his left hand, and when asked to write a sentence or other logical construct, could only do so with his right hand. If you want to find out more about the expirement, google Roger Sperry and Split Brain
The just of it is that your right hand is better suited for linguistic and logical tasks, and your left artistic endevours.
Last edited by @nthony; 07-17-2007 at 06:52 PM.
Rather than an interesting experiment it's a good skill to acquire since whatever hand you feel writing or painting or whatever you'll use it. I've done that in school, and instead of using my right hand I'd write with left unless writing essays etc. It took me about a full year to get my writing fairly clear, readable and generally pleasing to the eye, although in the beginning it didn't look good. I wasn't able to keep sentences in a straight line, and couldn't nicely write letters like a o d, that involved drawing circles etc :-) I still can see the difference between my left and right mainly because in my right letters are right-inclined while in my left, they're generally straight. Also, I'm not able to draw with my left even nearly as good as with my right but I think it just requires more time.
I think to get your other hand as good as the one you normally use requires many years of work (like writing paragraphs every day, and doing chores with it) since look how many years you've been using it - your age minus maybe 2 or 3. For instance, although I can write fairly good, it's not so fairly simple to quickly open a padlock with my left or use a computer mouse.
Besides, even a finer skill to learn is writing with both hands at the same time. I think it's possible, although I've never seen anyone doing it. I tried but couldn't. Whenever I'd try, my brain would somehow switch to the hand I wanna use, and interrupt the other.
Actually, both halves would probably claim to be the "real you." But if you try to follow your consciousness as an unbroken train from birth until the separating event, what happens at that instant?
My opinion (with no real basis) is that the original conscious being simply ceases to exist, and is replaced by two NEW conscious beings cohabitating in the same body. I can't think of anything else which makes any sense.
Starting at the middle of the page, and writing out to both edges at the same time (with one being the mirror of the other) has to be a neat party trick
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
The textbook goes on further to say that:Instead of the normally unified single stream of consciousness, these patients, behave in many wasy as if they have two independent streams of conscious awareness, one in each hemishpere, each of which is cut off from and out of contact with the mental experience of the other" (Sperry 1968: 724).So it suggests exactly as you said, that split-brain individuals experience a type of duality of consciousness, which is indeed quite amazing to think about (and the sort of things that turned me onto pyschology in the first place). I guess it could be compared to something a schizophrenik or split-personality would experience, although not even they have two active consciouses at one time. Although, from the testimonial of the female patient ("I didnt do that"), it would appear that "she" was operating primarly from one consciousness (the one that "didnt do it"), which leads me to posit that cerebral dominance (i.e. if your right handed, you have left-cerebral dominance) may play a part in determining for these individuals which consciousness is dominant.a) if the corpus callosum is cut, the two hemispheres function independently
b) each hemisphere seems to possess consciousness, but without awareness of the other (in one case, a patient, seeing her left hand make a response, exclaimed, "I didn't do that!")
c) the two hemispheres seem to show different types of specialized abilities, with the left hemisphere usually possessing language, logic and maths skills, and the right hemisphere spatial and musical skills.
It also gives rise to the question of where consciousness resides in the brain. It seems to be amorphous, merging into one stream of consciouness in normal individuals, but still existing as two in split-brain individuals. The textbook, mentions the view (and one that I would subscribe to) that Sperry referred to this as the emergent property of the brain which states that no one individual part or area is responsible for consciousness, rather that it is a result of the system working as a whole, in synchronization (or in the case of split-brain individuals, two wholes).
Last edited by @nthony; 07-20-2007 at 01:04 AM.
Suppose a split-brain individual is suffering from crippling seizures in both hemispheres. These seizures are determined to be caused by damage from severing the c. callosum. As it turns out, the only way to stop these life-threatening seizures is to remove one of the two halves of the brain.
So there are two fully conscious beings at stake. Both of them know that neither of them will survive unless one is killed. Both have a certain degree of control over what the body does. What will they do?
Also, suppose you are a doctor caring for such a patient. Will you make decisions based solely on what the "talking half" of the brain is saying? There is a whole other hemisphere, presumably conscious, which cannot easily voice its opinions. Surely, in such a case the patient would say "cut the right side out," but is this really what you should do?
What if the doctor lies to the patient about which side of the brain is dominant? If the doc says, "It's your right hemisphere which can speak with me now," but it's actually the left, the patient might say "Then cut out the left hemisphere." But since it is a lie, the half which spoke is committing suicide unwittingly.
Is the doctor then guilty of murder?
Interesting... from some of the studies I've heard of that deal with Traumatic Brain Injury, and removal of parts of the brain, I think they literally might be reduced to half-a-brain, as was the case with a young boy who survived a gunshot wound that caused almost the entirety of his right hemisphere to be removed. Although he could still "function" (motor skills, basic thought etc) his brain power was effectively crippled (was reduced to the intelligence level of a 6-year-old I believe). Although this was based on traumatic injury, so it'd be hard to extrapolate for certain if these events would occur in proper surgical removal. I believe though, at the very least, the person would be lose the functionality of almost half their body, as well as most skills (linguistic/logical or artistic/spatial) responsible of the lost half. Also, the book mentions that, although split, the two hemispheres still were able to collaborate effectively (externally through visual/verbal/etc communication rather than internally):Its as if two different people were using the same body to communicate with each other to achieve a common goal. Because of this, I'd tend to agree that "removing" a sphere might be considered murder, but only half-murder! Though in any case you'd be severly crippling the mental ability of the patient, and would probably be equivalent to killing their "person" (which exists as a sort of "team" or symbiot). I'd guess I'd liken it to splitting siamese twins, if one has to die, choose the one with the most to potentially gain (most likely the dominant one); if I were a split-brain stenographer (or some other logical/linguistic task that does not require much creativity), I'd have to part with "mr. right", whereas if I were an aspiring artist, I think both halves might agree after a long debate (if it were an actual vocal debate, that would truly be an interesting experience) that it would be best to let if the left one "left" (excuse the crappy puns...).Over time, it even seems that indirect methods of communicating between the two sides develop. For example, in one experiment, Sperry flashed either a red or green card to the left visual field (right hemishpere), and then asked the person to name (left hemisphere) the colour. As expected, the left hemishpere, not having seen the colour, did poorly. However, if allowed to reconsider, the person was always correct. What seemed to happen was that the right hemisphere, hearing the spoken response of the left hemisphere, would produce grimaces and other gesutures if the answer was wrong. These cuse let the left hemishpere know its error, which it then corrected!
I really do see this whole field taking of in the far future though when the biological breakthrough that allows us to accurately interface with the brain occurs, and people can essentially "network" with each other. This would then mean that the entirety of humanity would cease to exist as individuals and instead become one unified, streamed consciousness, which, (as partially a result of studying this material) has been for a while now my invision of and achievement goal for humankind in the far future.