staff_bob@gsbacd.uchicago.edu (01/19/89)
> >Jaynes was referring to a two-chambered brain, literally the left and >right hemispheres. His theory was, until further evolution of the >corpus callosum (which he supposed to have happened, oh, after _The >Odyssey_, but before completion of _The Iliad_) early man "heard" >voices from his right hemisphere, and interpreted these to be the >voices of gods. > I believe that Jaynes explicitly states that he believes that most of the evolution was social, while at the same time leaving open the possibilty of bio-physical evolution. I do not recall him ever discussing evolution of the corpus callosum. This is not so far fetched. In many so-called mystical writings, one sees admonitions to 'unlearn' or 'relearn' perception. This is manifest in Bhuddism, and for that matter, explicit in the works of Carlos Casteneda. This is consistent with Jayne's position, insofar as he holds that as civilization progressed, became more rational and left brain dominant, it became more and more difficult for right brain (read mystical) activity to occur. He goes into great detail explaining how rituals became more and more a part of the oracular experience, because they were requisite to breaking down socially established barriers. He points out that the best oracles were almost exclusively uneducated peasant girls, not so much because their brains hadn't evolved, but because they were less acculturated into the left brain dominant world. In article <7301@venera.isi.edu>, smoliar@vaxa.isi.edu (Stephen Smoliar) writes... >Granting that you HAVE >the sort of right hemisphere you want to "clean up" (and I tend to agree >with Minsky that one should be suspicious of such brain division), I'm sorry, but I'm going to have to call you (and Minsky) out on this one. Exactly what do you mean, 'that one should be suspicious of such brain division'? Left/Right brain laterality wasn't invented by Julian Jaynes. There's a very extensive body of research, approaching 20 years in age, that effectively *proves* differences between left and right hemispheric processing. Sperry, the researcher who 'discovered' the phenomenon while examining fomer epileptics who had had their corpus callosum cut, was recently awarded the Nobel prize in biology. It might be convenient for Minsky to ignore this sound, scientific research, just as it's convenient for him to ignore the fact that he hasn't made a significant contribution to the field of AI since it was in its infancy, and most of the trails he blazed have turned out to be dead ends, but that makes it no less valid. The fact is that there *are* differences between the operations of the two hemispheres. We have a somewhat better understanding of the left brain than the right, but I would point out that this is most probably because it is much easier for us to create a verbal description of the properties of the verbal side of the brain. Certainly, we are far from knowing all that there is to know, but we are well beyond the point where it is prudent to be 'suspicious of such a brain division'. (What follows has no sound basis in the above mentioned research, it is mere speculation/hypothesis on my part.) It seems to me that such suspicions have their origin in the age old polemic of 'reason' vs. 'mysticism' which quite probably has a biological origin in the different natures of the two hemispheres. Three thousand or so years ago it is quite probable that mysticism dominated reason, and this is not inconsistant with Jayne's hypothesis. Since then, we have seen left brain mediated processes, such as the use of symbolic logic and mathematics, rise in prestige until science has for some people completely supplanted the need for religion. History tells us that the rise of science included a long and difficult struggle against religious elements. One of the charges against Socrates was 'preaching false gods', and the travails of Galileo and Copernicus are well known. Mysticism in its heyday resisted science, and it is obvious from this newgroup that science in its heyday resists mysticism. As a trained Computer (MS) and Behavioral (AB) scientist, I too am inclined to respect the works of science vs. the mysteries of religion, but I am not prepared to reject something simply because I have no respect for it and do not understand it. It almost seems that the more scientific (left brained) one is, the less mystical (right brained) he *can* be, and vice versa. Thus the scientist cannot understand the mystic, nor can the mystic explain himself to the scientist. Is it not possible that the modern day scientist is just as prejudiced against the claims of right brain mediated knowledge as the priests of the Middle Ages were against science?
smoliar@vaxa.isi.edu (Stephen Smoliar) (01/20/89)
In article <1470@tank.uchicago.edu> staff_bob@gsbacd.uchicago.edu writes: >> >In article <7301@venera.isi.edu>, smoliar@vaxa.isi.edu (Stephen Smoliar) >writes... > >>Granting that you HAVE >>the sort of right hemisphere you want to "clean up" (and I tend to agree >>with Minsky that one should be suspicious of such brain division), > >I'm sorry, but I'm going to have to call you (and Minsky) out on this one. >Exactly what do you mean, 'that one should be suspicious of such brain >division'? Left/Right brain laterality wasn't invented by Julian Jaynes. >There's a very extensive body of research, approaching 20 years in age, >that effectively *proves* differences between left and right hemispheric >processing. Sperry, the researcher who 'discovered' the phenomenon while >examining fomer epileptics who had had their corpus callosum cut, was >recently awarded the Nobel prize in biology. It might be convenient for >Minsky to ignore this sound, scientific research, just as it's convenient >for him to ignore the fact that he hasn't made a significant contribution >to the field of AI since it was in its infancy, and most of the trails >he blazed have turned out to be dead ends, but that makes it no less >valid. > I think this matter might best be resolved by my citing Minsky's expression of his suspicions which I agree with (these paragraphs are from Section 11.8 of THE SOCIETY OF MIND): ********************************************************************** The two hemispheres of the brain look so alike that they were long assumed to be identical. Then it was found that after those cross-connections are destroyed, usually only the left brain can recognize or speak words, and only the right brain can draw pictures. More recently, when modern methods found other differences between those sides, it seems to me that some psychologists went mad--and tried to match those differences to every mentalistic two-part theory that ever was conceived. Our culture soon became entranced by this revival of an old idea in modern guise: that our minds are meeting grounds for pairs of antiprinciples. On one side stands the Logical, across from Analogical. The left-side brain is Rational; the right side is Emotional. No wonder so many seized upon this pseudoscientific scheme: it gave new life to nearly every dead idea of how to cleave the mental world into two halves as nicely as a peach. What's wrong with this is that each brain has @i[many] parts, not only two. And though there are many differences, we also ought to ask about why those left-right brain halves are actually so similar. What functions might this serve? For one thing, we know that when a major brain area is damaged in a young person, the mirror region can sometimes take over its function. Probably even when there is no injury, an agency that has consumed all the space available in its neighborhood can expand into the mirror region across the way. Another theory: a pair of mirrored agencies could be useful for making comparisons and for recognizing differences, since if one side could make a copy of its state on the other side then, after doing some work, it could compare those initial and final states to see what progress had been made. My own theory of what happens when the cross-connections between those brain halves are destroyed is that, in early life, we start with mostly similar agencies on either side. Later, as we grow more complex, a combination of genetic and circumstantial effects lead one of each pair to take control of both. Otherwise, we might become paralyzed by conflicts, because many agents would have to serve two masters. Eventually, the adult managers for many skills would tend to develop on the side of the brain most concerned with language because those agencies connect to an unusually large number of other agencies. The less dominant side of the brain will continue to develop, but with fewer administrative functions--and end up with more of our lower-level skills, but with less invovlement in plans and higher-level goals that engage many agencies at once. Then if, by accident, that brain half is abandoned to itself, it will seem more childish and less mature because it lags so far behind in administrative growth. *************************************************************** I do not feel that Minsky is in any way writing off Sperry's observations in this passage. I think he is only cautioning us against interpreting them too simplistically. Much of THE SOCIETY OF MIND is concerned with similar messages--that we should not be seduced by simple answers to complicated issues. Perhaps it is this attitude which exposes him to AD HOMINEM attacks such as the one expressed above. Unfortunately, we are too easily seduced by simplicity, which is why many folks seems a lot more inclined to cite Jaynes and Casteneda than to cite Minsky.
rwallace@vax1.tcd.ie (01/21/89)
In article <1470@tank.uchicago.edu>, staff_bob@gsbacd.uchicago.edu writes: >>Granting that you HAVE >>the sort of right hemisphere you want to "clean up" (and I tend to agree >>with Minsky that one should be suspicious of such brain division), > > I'm sorry, but I'm going to have to call you (and Minsky) out on this one. > Exactly what do you mean, 'that one should be suspicious of such brain > division'? Left/Right brain laterality wasn't invented by Julian Jaynes. > There's a very extensive body of research, approaching 20 years in age, > that effectively *proves* differences between left and right hemispheric > processing. Sperry, the researcher who 'discovered' the phenomenon while > examining fomer epileptics who had had their corpus callosum cut, was > recently awarded the Nobel prize in biology. It might be convenient for > Minsky to ignore this sound, scientific research, just as it's convenient > for him to ignore the fact that he hasn't made a significant contribution > to the field of AI since it was in its infancy, and most of the trails > he blazed have turned out to be dead ends, but that makes it no less > valid. Nobody is denying that there are differences in operation between the left and right hemispheres of the brain. What Minsky is criticizing is the tendency of some people to think that _everything_ can be explained by the left/right division. There are plenty of other productive lines of approach, such as studying the interaction between different levels of the mind, or different systems. And statements that a major figure in AI research hasn't made a significant contribution since the field was in its infancy are all the better for evidence to back them up. "To summarize the summary of the summary: people are a problem" Russell Wallace, Trinity College, Dublin rwallace@vax1.tcd.ie
staff_bob@gsbacd.uchicago.edu (01/21/89)
>I do not feel that Minsky is in any way writing off Sperry's observations in >this passage. I think he is only cautioning us against interpreting them too >simplistically. Much of THE SOCIETY OF MIND is concerned with similar >messages--that we should not be seduced by simple answers to complicated >issues. Perhaps it is this attitude which exposes him to AD HOMINEM attacks >such as the one expressed above. Unfortunately, we are too easily seduced by >simplicity, which is why many folks seems a lot more inclined to cite Jaynes >and Casteneda than to cite Minsky. To begin, I would like to apologize for appearing to cite Casteneda and Jaynes. My mention of Casteneda was intended to demonstrate that mystics often seem to explicitly cite abnegation of reason as a prerequisite to understanding their own, mystical 'truths'. One need not look so far afield to find similar critiques of reason. See for example, "The Dreams of Reason" by the physicist, Heinz R. Pagel. As for Jaynes, he is frequently cited in this conference and provides a convenient point of reference. I do not consider him an authority, and would not cite him as such. More to the point, I guess the question is, who's being easily seduced by simplicity? For example, in your citation from Minsky, he states (Minsky) >For one thing, we know that when a major brain area is damaged in a >young person, the mirror region can sometimes take over its function. We do often observe brain damaged children to do a much better job of compensating for their injuries than similarly disadvantaged adults. Minsky has seized upon this fact and used it to support his own wishful thinking. He would like us to believe that this compensation implies an initial equivalence of hemispheric capabilities. The point Minsky wishes to make has not escaped psychologists, who have endeavored to study it. See Denckla,M.B. et.al, "The Development of a Spatial Orientation Skill in Normal, Learning Disabled, and Neurologically Impaired Children," pp.44-59, of "Biological Studies of Mental Processes", MIT Press 1980. They state, for example, "Even when brain damage is more subtle, inferred from signs, and presumably congenital, right-hemispheric deficit contributes mores heavily to impaired spatial performance in children than does left." Moreover, when there is compensation for damaged areas of the brain, it is not clear that this compensation is achieved by the mirror region in the other hemisphere. What is clear is that "the likelihood of language disturbances to one cerebral hemisphere is greater with left than with right lesions. In infancy, the two hemispheres are not equally at risk for disordered language." (M. Dennis an H.A. Whitaker "Hemispheric Equipotentiality and Language Acquisition). (Minsky) >My own theory of what happens when the cross-connections between those brain >halves are destroyed is that, in early life, we start with mostly similar >agencies on either side. Later, as we grow more complex, a combination of >genetic and circumstantial effects lead one of each pair to take control of >both. An interesting theory, which has been disproven any number of times. See, for example, the chapter entitled "Infant Cerebral Asymmetry", by Dennis Molfese, which appears in the book "Language Development and Neurological Theory" (Academic Press 1977). The fact is that we can find evidence of hemispheric specialization in very early in life. Hemispheric asymmetry a very complex subject, and not only is Minsky guilty of gross over simplifications, his position contradicts a large body of established research. The hemispheres *are* different from the start. Is it not Minsky himself who wishes to seduce us with simplistic arguments? Is he not misleading us in order to discourage us from wondering about the irrational component of the human mind ? Jaynes and Casteneda both raise far more questions than they answer. There seem to be quite a few people who, like Minsky, wish to dismiss these questions out-of-hand, as somehow being beneath them. That is the simple path. The difficult path is to leave them open and examine them, to construct hypotheses and to test them experimentally. The simple path is the self serving pop-logic exhibited here by Minsky. The difficult path is the path of science. To be fair, I believe that it is safe to say that the left brain is not exclusively logical, nor is the right brain completely analogical. Minsky is quite correct in his belief that the two halves of the brain seem to be much more alike than different. The fact is that the brain, taken as a whole, is both logical and analogical. This is not the point. The point is that the focus of what is now called 'Artificial Intelligence' is today almost exclusively upon the logical, rational, symbol processing aspects of human intelligence, while it is clear that a considerable part of the human mind seems to be thus excluded from consideration. As for 'AD HOMINEM' attacks, what is the point of Minsky's >More recently, when modern methods >found other differences between those sides, it seems to me that some >psychologists went mad--and tried to match those differences to every >mentalistic two-part theory that ever was conceived. it may be convenient and even humorous to characterize people with whom he disagrees as mad, but *if* such an attempt was made, it was not madness, it was science.
smoliar@vaxa.isi.edu (Stephen Smoliar) (01/24/89)
In article <1511@tank.uchicago.edu> staff_bob@gsbacd.uchicago.edu writes: > >To be fair, I believe that it is safe to say that the left brain is >not exclusively logical, nor is the right brain completely analogical. >Minsky is quite correct in his belief that the two halves of the brain >seem to be much more alike than different. The fact is that the brain, >taken as a whole, is both logical and analogical. This is not the point. >The point is that the focus of what is now called 'Artificial Intelligence' >is today almost exclusively upon the logical, rational, symbol processing >aspects of human intelligence, while it is clear that a considerable part of >the human mind seems to be thus excluded from consideration. > This is certainly an important point, and I think it is both recognized and honored in THE SOCIETY OF MIND. Minsky's K-line theory of memory represents an attempt to get away from the "propositional" nature of a symbol processing approach to memory in favor of a more "dispositional" approach. Of course, there are a lot of loose ends in what Minksy has written so far; but THE SOCIETY OF MIND is deifnitely not confined to the aforementioned narrow view of artificial intelligence. Another researcher who has tried to get away from these narrow confines is Gerald Edelman, who view his selectionism as an alternative to the symbol manipulation of information processing psychology.
diana@saqqara.cis.ohio-state.edu (Diana Smetters) (01/24/89)
To add a few small points about the discussion on lateral specialization
in brain function, Minsky, and mysticism:
In article <1511@tank.uchicago.edu> staff_bob@gsbacd.uchicago.edu writes:
< (Minsky)
< >My own theory of what happens when the cross-connections between those brain
< >halves are destroyed is that, in early life, we start with mostly similar
< >agencies on either side. Later, as we grow more complex, a combination of
< >genetic and circumstantial effects lead one of each pair to take control of
< >both.
<
< An interesting theory, which has been disproven any number of times. See,
< for example, the chapter entitled "Infant Cerebral Asymmetry", by Dennis
< Molfese, which appears in the book "Language Development and Neurological
< Theory" (Academic Press 1977). The fact is that we can find evidence of
< hemispheric specialization in very early in life.
I have a question about arguments which mention that hemispheric
specialization is present "from the start" or "very early in life"
and then go on to use the presence of this specialization to deduce that
such specialization is innate. Namely: how early is "very early" -- if
you consider the fact that evidence that a particular pattern of hemispheric
specialization is present in the 2yr old child, or even the 3 month
old infant does not constitute evidence that such specialization is
genetically predetermined. A 3 month old infant has already been subject
to a large number of "environmental" influences -- both at the level
of the uterine environment and at the cellular level, in terms of the
chemical influences on the migrating neurons.
I don't want to argue against the point that hemeispheric specialization
is, to at least some degree, genetically determined -- I just want to
emphasize the point that mounting evidence indicates that environmental
effects on development occur much earlier than is usually considered
in arguments of the form "x is true of small children/infants, so x must be
genetically determined".
In addition, I wish to mention that the fact that all individuals seem
to undergo some pattern of hemispheric specialization does not mean that
all individuals undergo the *same* pattern of hemispheric specialization.
(See Geschwind and Galaburda: "Cerebral Dominance" and "Cerebral
Lateralization").
< To be fair, I believe that it is safe to say that the left brain is
< not exclusively logical, nor is the right brain completely analogical.
Lastly, and most emphatically: the evidence to date concerning cerebral
lateralization has focused primarily around lesion studies. There is
evidence of such things as: lesions to areas of the left hemisphere
(ex. Broca's area) tend to produce certain types of language dysfunction.
From this, one can deduce things like "many aspects of language function
may be carried out by the left hemisphere (in most people)". This
does not give any evidence for the claims that the left hemisphere
is logical/analytical, while the right is concerned with creativity,
art, etc. If anyone could give me references that show this sort of
lateralization of higher cognitive functions like "logical thought",
"creativity", "aesthetics", etc., I would really appreciate it. The
fact that the left hemisphere may handle the bulk of low-level language
processing, and that the right may handle spatial processing and the
generation of mental images (to be kept strictly distinct from the
process known as imagination), does not seem (to me, at least) to constitute
evidence for the lateral specialization of any of the high-level
cognitive processes which have been discussed here (under the denotation
"mysticism").
--Diana Smetters
OSU Laboratory for AI Research
diana@cis.ohio-state.edu
geb@cadre.dsl.PITTSBURGH.EDU (Gordon E. Banks) (01/24/89)
I don't want to be seen as supporting any claims about mysticism, but the fact that lateralization is genetic is quite clear. Left-handedness can be shown to be genetic, and most mammals who are territorial have lateralization of function within the hemispheres. The locus of the genes is not known and is probably complex, but it is known that Turner's syndrome (XO) patients have deficient lateralization. It is true that most of the knowledge about it is gained from lesion studies, but other studies involving dynamic PET scanning have backed these up. In addition to the spatial capabilities of the right hemisphere, it appears to be more responsible for affective behavior. By that I mean it has more to do with understanding and expressing emotion than does the left. Right hemisphere strokes may produce a patient often incapable of expressing emotion, or understanding other peoples' emotional states. Howard Gardner has postulated that the right hemisphere contains the person's "theory of mind" such that once that is lesioned, the person become less able to consider other people as having minds and to empathize. Certainly this would be in line with studies of psychopaths which show deficiency in the right hemisphere.
meadors@nprdc.arpa (Tony Meadors) (01/27/89)
In article <1511@tank.uchicago.edu> staff_bob@gsbacd.uchicago.edu writes: >>I do not feel that Minsky is in any way writing off Sperry's observations in >>this passage. I think he is only cautioning us against interpreting them too >>simplistically. Much of THE SOCIETY OF MIND is concerned with similar >>messages--that we should not be seduced by simple answers to complicated >>issues. > >To begin, I would like to apologize for appearing to cite Casteneda and >Jaynes. My mention of Casteneda was intended to demonstrate that mystics >often seem to explicitly cite abnegation of reason as a prerequisite to >understanding their own, mystical 'truths'. One need not look so far >afield to find similar critiques of reason. So, you have something against "reason." When one gives up reasoning as religion and mysticism often requires then 'truths' needn't be. >We do often observe brain damaged children to do a much better job of >compensating for their injuries than similarly disadvantaged adults. >Minsky has seized upon this fact and used it to support his own wishful >thinking. He would like us to believe that this compensation implies >an initial equivalence of hemispheric capabilities. >.... >Moreover, when there is compensation for damaged areas of the brain, it >is not clear that this compensation is achieved by the mirror region in >the other hemisphere. What is clear is that It would seem to me, the fact that other, non-mirror areas can adapt to perform the neccesary processing, strengthens not weakens an argument for brain equipotentiality. >>My own theory of what happens when the cross-connections between those brain >>halves are destroyed is that, in early life, we start with mostly similar >>agencies on either side. Later, as we grow more complex, a combination of >>genetic and circumstantial effects lead one of each pair to take control of >>both. > >An interesting theory, which has been disproven any number of times. See, >for example, the chapter entitled "Infant Cerebral Asymmetry", by Dennis >Molfese, which appears in the book "Language Development and Neurological >Theory" (Academic Press 1977). The fact is that we can find evidence of >hemispheric specialization in very early in life. He did not deny a predisposition measurable early in life. You evidently didn't notice the word "genetic" above. >Hemispheric asymmetry a very complex subject, and not only is Minsky guilty >of gross over simplifications, his position contradicts a large body of >established research. The hemispheres *are* different from the start. Is it >not Minsky himself who wishes to seduce us with simplistic arguments? Is he >not misleading us in order to discourage us from wondering about the >irrational component of the human mind ? Jaynes and Casteneda both raise >far more questions than they answer. There seem to be quite a few >people who, like Minsky, wish to dismiss these questions out-of-hand, >as somehow being beneath them. That is the simple path. The difficult >path is to leave them open and examine them, to construct hypotheses and >to test them experimentally. The simple path is the self serving pop-logic >exhibited here by Minsky. The difficult path is the path of science. Minsky is being cautious. Neither he (nor I) am calling for blanket generalizations concerning the localization of "types of analysis" betwixt the hemisheres. Minsky is one of the most repected AI researchers and theorists of mind of our age. To dismiss his "path" as "pop-logic" in favor of Jaynes and (you've got to be kidding) Casteneda is a grave injustice. The pop-path here is to take the evidence of "somewhat polarized behavioral deficits" from damage to either side of the brain and turn it into some sort of holy grail of organization: postulating a rational/irrational or logical/emotional tug of war. The pop notion is that one hemisphere provides an logical analysis and the otherside provides a wholistic analysis of any given situation. This is not supported by the evidence. >The point is that the focus of what is now called 'Artificial Intelligence' >is today almost exclusively upon the logical, rational, symbol processing >aspects of human intelligence, while it is clear that a considerable part of >the human mind seems to be thus excluded from consideration. I agree. This is the point. The point is that some would take the laterlization evidence as "clearly" showing that the "right" hemisphere is doing some "special, non-logical, intuitive" processing that is distinct from a more "analytic kind." More to the point, the finding that damage to the left causes a greater decrement to languange and reasoning skills while damage to the right to spatial-temporal skills does not show that "a considerable part of the human mind" is devoted to some analogical or irrational aspect of human intelligence. It doesn't even show that those activities are "largely performed by those regions." To interpret a deficit as indicating that those activities impaired are performed "there" is the most common mistake of all in interpreting the data of neuroscience. They usually alert students to this, over and over, in those courses. > > [no name provided] > If I didn't make it clear enough, I object to the claim that the hemisheres are doing different and complementary types of analyses as well as the idea that some fundamentally "irrational" component need be added to models of intelligence. While the traditional AI approaches are of course early and crude attempts at capturing our processing character this is not a fundamental failure to capture some "artistic half" as some would have it. AI is in need of a new paradigm (perhaps pdp control systems), not an "irrational twin" theory. tonyM
staff_bob@gsbacd.uchicago.edu (01/28/89)
>In article <1511@tank.uchicago.edu> staff_bob@gsbacd.uchicago.edu writes: >>>I do not feel that Minsky is in any way writing off Sperry's observations in >>>this passage. I think he is only cautioning us against interpreting them too >>>simplistically. Much of THE SOCIETY OF MIND is concerned with similar >>>messages--that we should not be seduced by simple answers to complicated >>>issues. >> >>To begin, I would like to apologize for appearing to cite Casteneda and >>Jaynes. My mention of Casteneda was intended to demonstrate that mystics >>often seem to explicitly cite abnegation of reason as a prerequisite to >>understanding their own, mystical 'truths'. One need not look so far >>afield to find similar critiques of reason. > > So, you have something against "reason." When one gives up reasoning >as religion and mysticism often requires then 'truths' needn't be. > I have nothing against reason, nor do I profess any sort of faith in any sort of theism or mystical system. If I appear to be advocating an abnegation of reason, Mr.Meadors has misread me. I am trying to point out that the dialectic between what I have generally termed 'mysticism' and its opposite, which I prefer to call 'reason' may in fact be the result of a naturally occurring dichotomy in the structure of the brain. In my mind, this in no way invalidates reason, nor does it raise the stature of mysticism vis a vis reason. I admit that this is a hypothesis, and it has not been proven by research. However, it has not been disproven either, and to me it seems to fit very well with what we have observed. To insinuate from the above passage that I 'have something against "reason"' is insulting, and I believe Mr.Meadors intends it to be so. >>We do often observe brain damaged children to do a much better job of >>compensating for their injuries than similarly disadvantaged adults. >>Minsky has seized upon this fact and used it to support his own wishful >>thinking. He would like us to believe that this compensation implies >>an initial equivalence of hemispheric capabilities. >>.... >>Moreover, when there is compensation for damaged areas of the brain, it >>is not clear that this compensation is achieved by the mirror region in >>the other hemisphere. What is clear is that > > It would seem to me, the fact that other, non-mirror areas can adapt >to perform the neccesary processing, strengthens not weakens an argument >for brain equipotentiality. > Since Mr.Meadors has obviously read my posting, it appears that there are certain points which he is either deliberately ignoring, or which he does not understand. Immediately below this passage I provided the following citation: See Denckla,M.B. et.al, "The Development of a Spatial Orientation Skill in Normal, Learning Disabled, and Neurologically Impaired Children," pp.44-59, of "Biological Studies of Mental Processes", MIT Press 1980. "Even when brain damage is more subtle, inferred from signs, and presumably congenital, right-hemispheric deficit contributes mores heavily to impaired spatial performance in children than does left." This quotation, the entire article referenced and the bulk of evidence I have seen weakens the argument against equipotentiality. If a part of the left hemisphere is injured, and the deficit is compensated for by another part of the left hemisphere, I see no way in which the strengthens the argument for it. >>>My own theory of what happens when the cross-connections between those brain >>>halves are destroyed is that, in early life, we start with mostly similar >>>agencies on either side. Later, as we grow more complex, a combination of >>>genetic and circumstantial effects lead one of each pair to take control of >>>both. >> >>An interesting theory, which has been disproven any number of times. See, >>for example, the chapter entitled "Infant Cerebral Asymmetry", by Dennis >>Molfese, which appears in the book "Language Development and Neurological >>Theory" (Academic Press 1977). The fact is that we can find evidence of >>hemispheric specialization in very early in life. > > He did not deny a predisposition measurable early in life. > You evidently didn't notice the word "genetic" above. Yes, and I also noticed the word 'mostly'. Dr.Minsky has equivocated quite nicely. It seems clear from the passage that he intends to downplay the differences between the hemispheres. If he is not denying an early predispostion to brain asymmetry what is the point of the use of the word 'later'? > >>Hemispheric asymmetry a very complex subject, and not only is Minsky guilty >>of gross over simplifications, his position contradicts a large body of >>established research. The hemispheres *are* different from the start. Is it >>not Minsky himself who wishes to seduce us with simplistic arguments? Is he >>not misleading us in order to discourage us from wondering about the >>irrational component of the human mind ? Jaynes and Casteneda both raise >>far more questions than they answer. There seem to be quite a few >>people who, like Minsky, wish to dismiss these questions out-of-hand, >>as somehow being beneath them. That is the simple path. The difficult >>path is to leave them open and examine them, to construct hypotheses and >>to test them experimentally. The simple path is the self serving pop-logic >>exhibited here by Minsky. The difficult path is the path of science. > > Minsky is being cautious. Neither he (nor I) am calling for blanket >generalizations concerning the localization of "types of analysis" >betwixt the hemisheres. Nor am I. I realize that characterizing one half of the brain as logical and the other as analogical is fraught with difficulties. However, it is clear from what evidence we have that the two hemispheres are different, and that the nature of the differences lie along these lines. It is convenient, and I believe not wholly innaccurate to speak of the differences is this way. More to the point, as I have said, I believe that the difference between the hemispheres is fundamental to the way we think. From what I can gleen from this passage, Minsky does not appear to agree. To qoute Sperry, "The normal bilateral conciousness can be viewed as a higher emergent entity that is more than just the sum of its right and left awareness and supersedes this as a directive force in our thoughts and actions." > Minsky is one of the most repected AI researchers and theorists of mind >of our age. To dismiss his "path" as "pop-logic" in favor of Jaynes and >(you've got to be kidding) Casteneda is a grave injustice. The pop-path >here is to take the evidence of "somewhat polarized behavioral deficits" >from damage to either side of the brain and turn it into some sort of >holy grail of organization: postulating a rational/irrational or >logical/emotional tug of war. The pop notion is that one hemisphere >provides an logical analysis and the otherside provides a wholistic >analysis of any given situation. This is not supported by the evidence. > From Sperry, who in some quarters recieves quite as much respect as Minsky: "the mute, minor hemisphere is specialized for Gestalt perception, being primarily a synthesist in dealing with information input. The speaking, major hemisphere, in contrast, seems to operate in a more logical, analytical fashion." ("The Three Pound Universe", 222-223) Again, Mr.Meadors does not appear to be understanding what he has obviously read. Nowhere in my posting did I make an argument in favor of Jaynes and Casteneda, except to say that they have raised a lot of questions. In fact, I explicitly apologize for having appeared to do so in a previous article, in which I also mentioned Bhuddism. He cited the above passage >>To begin, I would like to apologize for appearing to cite Casteneda and >>Jaynes. My mention of Casteneda was intended to demonstrate that mystics >>often seem to explicitly cite abnegation of reason as a prerequisite to >>understanding their own, mystical 'truths'. One need not look so far >>afield to find similar critiques of reason. and, I might add, left out the next lines: >>See for example, "The >>Dreams of Reason" by the physicist, Heinz R. Pagel. As for Jaynes, he >>is frequently cited in this conference and provides a convenient point >>of reference. I do not consider him an authority, and would not cite him >>as such. My dismissal of Minsky's 'logic' was not in favor of that of Jaynes and Casteneda. It was in favor of Molfese, et.al. who have done research which demonstrates bilateral asymmetry in early life. The fact that Minsky is one of the giants of the field makes it all the more important that he not mislead people to make the facts appear to fit his theories. You say below that you "object to the claim that the hemispheres are doing different and complementary types of analyses", and I daresay that you believe Minsky does also. >>The point is that the focus of what is now called 'Artificial Intelligence' >>is today almost exclusively upon the logical, rational, symbol processing >>aspects of human intelligence, while it is clear that a considerable part of >>the human mind seems to be thus excluded from consideration. > >I agree. This is the point. The point is that some >would take the laterlization evidence as "clearly" showing that the >"right" hemisphere is doing some "special, non-logical, intuitive" processing >that is distinct from a more "analytic kind." More to the point, the >finding that damage to the left causes a greater decrement to languange >and reasoning skills while damage to the right to spatial-temporal skills >does not show that "a considerable part of the human mind" is devoted >to some analogical or irrational aspect of human intelligence. It doesn't >even show that those activities are "largely performed by those regions." >To interpret a deficit as indicating that those activities impaired are >performed "there" is the most common mistake of all in interpreting the >data of neuroscience. They usually alert students to this, over and over, >in those courses. >> You seem to imply that those some who feel that the left hemisphere is more analytical than the right, and that the right is more holistic than the left, are worse that inattentive students. Let me refer you to Bever,J (1975) "Cerebral asymmetries in humans are due to the differentiation of two incompatible processes: Holistic and analytic." In Aronson & Rieber (eds.) "Developmental psycholinguistics and communication disorders." New York Academy of Science." As far as I know, Bever paid attention in his elementary psychology classes. If one reads the literature, one sees very little evidence for hemispheric symmetry, with notable exceptions. In normal humans, EEG scans reveal that during most cognitive and motor tasks, both hemispheres do an approximately equal amount of 'work', regardless of the supposed lateralization of the task being performed. I paid attention in class too, and we were taught that the left hemisphere is tuned to time, the right to space, and that logic, counting, etc. were left lateralized skills. >> [no name provided] >> > If I didn't make it clear enough, I object to the claim that > the hemisheres are doing different and complementary types of > analyses as well as the idea that some fundamentally "irrational" > component need be added to models of intelligence. While the > traditional AI approaches are of course early and crude attempts > at capturing our processing character this is not a fundamental > failure to capture some "artistic half" as some would have it. > AI is in need of a new paradigm (perhaps pdp control systems), > not an "irrational twin" theory. > >tonyM Feel free to object. In my opinion, this theory does not fit the data. As for adding some fundamentally irrational component to models of intelligence, I'm not quite sure what this means. If we are trying to model the human brain, and so pass the Turing test, I don't see how we can do it without building in an irrational component. If, by 'intelligence', one wishes to exclude everything that is illogical and irrational, obviously no model of intelligence could include these components. I am not trying to say that the irrational, 'mystical', part of the brain can never be understood, and is fundamentally 'mystical'. Quite the contrary. I believe that it can be, and should be, understood, and that such an understanding is central to the understanding of the human mind. One final note. The tone of Mr.Meadors posting seems to me quite acrimonious, and I believe that is due in part to my rather personal attack of Dr.Minsky's credentials. I should know better than to villify a god, and as I have already confessed, my doing so was a hasty and ill-advised response to a posting in which Minsky was cited as an authority who was skeptical of the left/right brain division. My criticism that Minsky hadn't done anything for years was ignorant, as my only way of evaluating him was through references to him in the literature. I have not read "Society of Mind", except for one brief excerpt, but I fully intend to. I would therefore like to apologize for these remarks, and hope we can leave it at that. Bob Kohout