Quotes XIX

Quotations about
THE MODERN PHRENOLOGY OF THE CEREBRAL HEMISPHERES

IT SEEMS OBVIOUS THAT INDIVIDUAL DIFFERENCES IN HEMISPHERE FUNCTION WILL BE HIGHLY RELEVANT TO EXPLAINING HUMAN PSYCHOLOGICAL DIFFERENCES. YET THIRTY YEARS OF WELL-FUNDED RESEARCH WORK HAVE DRAWN VIRTUALLY A COMPLETE BLANK. (THERE IS NOT EVEN ANY IMPORTANT AND RELIABLY FOUND PSYCHOLOGICAL DIFFERENCE BETWEEN LEFT- AND RIGHT-HANDERS; AND THE RELIABLY FOUND SEX DIFFERENCE IN HEMISPHERE SPECIALIZATION REMAINS LARGELY UNEXPLAINED.) IT REMAINS TO BE CONSIDERED THAT THE NON-SPEECH HEMISPHERE USUALLY HOUSES EXPECTATIONS AND THAT THIS ACCOUNTS FOR ITS APPARENTLY SOMEWHAT 'GLOOMY' DISPOSITION; BUT FOR THE MOMENT THE BRAIN CERTAINLY REMAINS THE WORLD'S GREATEST MYSTERY.


The 1960's witnessed the Nobel-Prize-winning work of Roger Sperry on "split-brain" patients. (In these rare patients, the cerebral commissures had been partially severed by surgery to prevent massive epileptic attacks spreading from one cerebral hemisphere to the other). Subsequently, the study of the (putatively) distinguishable functions of the hemispheres became a growth industry in psychology. A person's 'lateralization' was commonly estimated in three main ways: (i) by handedness; (ii) by the visual field (to the right or left of the testee's central fixation) in which a person showed the best visual recognition of briefly presented target stimuli; (iii) with which ear a person showed best recognition of sounds. Thus twentieth-century neuropsychologists hoped to realize the ambition of the Edinburgh phrenologist, George Combe, that human nature and individuality might be read off from 'God's Other Book', the human brain.
At first the notion was that individual differences in hemispheric dominance might be linked to manifest differences in psychometric abilities. But left-handers (and mixed-handers) did not prove reliably obliging in such respects; nor did alternative assessments of a person's 'hemispheredness' produce any clear picture of correlated ability-differences. Faced with this disappointment, by the mid-1970's, interest began to focus on more grand but less definite and less measurable differences-e.g. on the 'parallel processing', 'creativity' or 'primary process thinking' that might possibly, by some criteria, be associated with relative right-hemisphere dominance (at least amongst right-handers). Again, however, little consistent support proved forthcoming for any one theory; and, by the mid-1980's, it was clear that numerous complexities required consideration-not least those of the interaction between the hemispheres (e.g. involving processes of mutual stimulation, compensation and suppression). By 1990, following the arrival of brain-scanning devices (PET, CAT, MRI) it was clear that the two hemispheres are remarkable chiefly for their similarity, at least in normal, commissure-intact people. The main conjecture must therefore be that the hemispheres are rather like identical twins: they are very similar, but one tends 'dominate' the other in behavioural output. [Evolutionarily, there is presumably an elementary need in ground-living mammals for action (movement) to alternate between left and right sides while still realizing one single plan. Perhaps, beyond that, it is simply advantageous-less accident-prone-for the brain to carry a 'back-up' system (in the non-dominant hemisphere) rather than to have all its eggs in one basket: for it would be unlikely that the same form of minor damage would disrupt the functioning of both hemispheres at the same time.]
Amidst all the sophisticated researches of neuropsychologists in the 1990's, remarkable extant problems are: (i) the failure to achieve any interesting and agreed account even of differences in handedness and their origins; (ii) the empirical failure to link indices of hemispheredness with well-established measures of the major six dimensions of personality that repeatedly emerge in psychometric work {see Quotes III}; and (iii) the reluctance to explore, in particular, the likelihood that general intelligence (g) itself is positively associated with cerebral differentiation of function-such differentiation (as expressed in consistent individual preferences in handedness) being conspicuously lacking in mentally retarded people. Researchers can barely say more than that, at least in right handers, the left hemisphere usually houses speech (Broca's area, discovered around 1860) and the right hemisphere houses dressing skills (discovered by Brain around 1940). At present there is general belief that, for whatever reason, males show greater cerebral differentiation of function, and that psychotic disorders are associated with unusual patterns of lateralization. As to hemisphere function, the tendency is to see the left hemisphere as more concerned with focussed attention and sequential, analytical processing of unpredictable material; while the right hemisphere seems more concerned with the holistic patterns, rhythms and expectations that provide the personal background and context to action. Despite its special association with music, song and dance, the right hemisphere is the more 'gloomy' of the two hemispheres-as if it especially housed recognition of negative and punishing features of the environment or was quite simply, the Freudian superego. {E.g. Crow, 1986, Brit. J.Psychiat.; Crow, 1993, Lancet; Cutting, 1992, Brit. J. Psychiat.; Rotenberg, 1993, Dynamische Psychiatrie.} It is sometimes suggested that the right hemisphere especially enables obedient response to authority, both in ordinary social life and under hypnosis. According to this view, normal, modern, non-hypnotized consciousness involves a certain dominance of left hemisphere activity (see Walker, 1984, Br.J.Soc.Psychol.; Jaynes, 1972/1992, The Origins of Consciousness in the Breakdown of the Bicameral Mind.) Perhaps the greater cerebral differentiation of males is somehow associated with their showing more 'extreme' forms of psychosis (notably the manic form of manic-depressive disorder) and social behaviour generally (for, historically at least, men are over-represented in the organisation of both crime and religion). By contrast, perhaps because of lower cerebral differentiation, the more common female shifts (in multiple-usually dual- personality (see Quotes VI)), involve neither such complete loss nor such complete tyranny of superego functions as are sometimes seen in males.






For coverage of intelligence (and 'differentiation') see:
BRAND, C.R. (1996) The g Factor.
Chichester : Wiley DePublisher.

"The nature and measurement of intelligence is a political hot potato. But Brand in this extremely readable, wide-ranging and up-to-date
book is not afraid to slaughter the shibboleths of modern "educationalists". This short book provides a great deal for thought
and debate."
Professor Adrian Furnham, University College London.
The book was first issued, in February, but then withdrawn, in April, by the 'publisher' because it was deemed to have infringed modern canons of
'political correctness.'
It received a perfectly favourable review in Nature (May 2, 1996, p. 33).

For a Summary of the book, Newsletters concerning the
de-publication affair, details of how to see the book for scholarly purposes, and others' comments and reviews,
see the Internet URL sites:
http://laboratory.psy.ed.ac.uk/DOCS/crb/internet.html
http://www.webcom.com/zurcher/thegfactor/index.html

For Chris Brand's 'Get Real About Race!'-his popular exposition of his views on race and education in the Black
hip-hop music magazine 'downlow' (Autumn, 1996)-see:
http://www.bhs.mq.edu.au/~tbates/intelligence/Brand_downlow.html






INDEX to QUOTES XIX
Page

(i) History 5

(ii) The phenomena of lateralization of function, right-
vs-left localization of function, a 'dominant hemisphere', and hemispheric interplay. 7

(iii) How does lateralization (etc.) develop? 10

(iv) The functional significance of lateralization, R-
vs-L
localization, 'dominance', and interplay. 12

(v) Individual (and group) differences in lateralization (etc.)
and their possible relation to differences in abilities and
propensities.
18

(vi)
Developmental origins (in 'nature' or 'nurture') of individual differences in lateralization. 26


Epilogue







(i) History


"In 1844, the eccentric English general practitioner, Arthur Ladbroke Wigan, came up with the idea that insanity ensued when the two brain hemispheres failed to act together in harmony."
A.S.DAVID, 1989, 'The split-brain syndrome'. British Journal of Psychiatry 154.

"I have never believed more profoundly than I do now that (human) character is based on (physical) organisation. I never had a higher appreciation than I have now of the services which phrenology has rendered towards the science of man. But I do not, and I think I never shall, consider every man shallow or unconscientious who is unable to embrace all Mr Combe's views of organology and psychology."
Miss Marian EVANS (alias George Eliot), 1855, after a visit to stay with the Combes in Edinburgh. Cited by Ian Hunter, 1994, Bulletin of the Scottish Branch of the British Psychological Society.

"Miss Marian Evans {alias George Eliot}....has been our guest for a fortnight.... She is a distinguished linguist, including Greek, Latin & Hebrew, German, French & Italian; an admirable musician; and is mistress of all the philosophies of modern times; & is a good political economist; also knows art well. Her brain is large; the anterior lobe & coronal region predominating. Temperament nervous lymphatic: pleasing but not pretty."
George COMBE, 1852, in his diary. Cited by Ian Hunter, 1994,
Bulletin of the Scottish Branch of the British Psychological Society.

"Phrenology is simply the physiology of the brain and its object is the correct exposition of the uses of the different parts of the brain....regarded as the organ of the mental faculties."
George COMBE, 1860.

"I would go without shirt or shoe,
Friend, tobacco or bread,
Sooner than lose for a minute the two
Separate sides of my head."
KIPLING, 'The two-sided man'.

"....the tendency to symmetry in the two halves of the cerebrum is stronger in women than in men." J. CRICHTON-BROWNE, 1879, Brain 2.

"[Among 'opposite' nineteenth-century characterizations of the functions of the two cerebral hemispheres were 'male' and 'female'.] The male hemisphere, as one writer put it in 1898, was "more intellectual,....more stable", the female "more excitable, more readily exhausted". White and non-White differences were, of course, also traceable to brain asymmetry.... Similarly, among the mad, the right, brutish side of the brain had conquered the rational left. Indeed, pathological studies revealed that the weight ratios of the hemispheres in the mad were, as one alienist discovered, "completely reversed"."
Christopher LAWRENCE, 1988, reviewing A.Harrington,
Medicine, Mind and the Double Brain.
Times Higher Educational Supplement, 14 iv.

"The search for generality in the study of brain mechanisms is no doubt laudable - but it seems more than likely that a theory of individual differences is a necessary prerequisite for success in this enterprise."
J.C.MARSHALL, 1973, Neuropsychologia 11.

"It is as easy to construct patterns in the laterality literature as in the Rorschach."
Marian ANNETT, 1980, Behavioral & Brain Sciences 3.

"Excessive generalization and premature conclusions have distorted the picture and encouraged the production of quite wild and certainly unfounded views of the nature and function of cerebral localization."
G.BEAUMONT, 1981.


"Phrenology was to the nineteenth century what psychoanalysis is to the twentieth."
Publisher's announcement, 1982. Greenwood Press.











(ii) The phenomena of lateralization of function, right-vs-left localization of function, a 'dominant hemisphere', and hemispheric interplay.


"If primary process functioning is linked to the right hemisphere, it is no longer possible to assume that it represents some sort of childlike, archaic process."
P.FONAGY, 1981.

"The right hemisphere seems to be especially involved in tasks requiring emotional analysis, particularly when the tone of the displayed emotion is negative."
Ruth CAMPBELL, 1982, International Journal of Psychology.

"[In 'confusional states' caused by right hemisphere damage] action and thought lose their normal coherence, the patient responds in an inappropriate manner, and the line of thinking becomes jumbled in a dramatic fashion.... The importance of the right hemisphere for attention and emotion, and for the configuration of space, all appear to be possibly related to this function."
N.GESCHWIND, 1982, Philosophical Transactions
of the Royal Society
, B298.

"Currently [a relatively] popular belief is that creativity is associated with right-brain processes (see Ornstein, 1977). There is, however, little relevant evidence to support this oversimplified theory (Springer & Deutsch, 1981), except possibly in the visual arts."
P.E.VERNON, 1987, in D.N.Jackson & J.P.Rushton,
Scientific Excellence. London : Sage.

"It is concluded that the right hemisphere does take part in certain formal linguistic aspects of comprehension, has some facility in propositional speech (or may develop it), has special responsibility for prosodic and emotional aspects of language, and may well support certain types of dysphasic speech."
G.E.POWELL, 1987, British Journal of Psychology 78.
(Reviewing C.Code, Language, Aphasia and the Right Hemisphere.)

"In neuropsychology, emphasis on laterality differences in cerebral organization has been replaced, to some extent, by a focus on selective cognitive disorders.... At least three patterns of hemispheric organization can be proposed: strongly unilateral (e.g. speech production); a posterior, possibly equal contribution, regardless of laterality (e.g. some aspects of visuo-spatial processing); and deficits that have been exclusively related to bilateral injury." Z.MEHTA, F.NEWCOMBE & G.RATCLIF, 1987, Bulletin of the British Psychological Society 40, A113.

"....the perception of communicative [distress] calls is lateralized to the left hemisphere in a comparatively lowly species - the house mouse.... Ehret [the researcher who discovered this] has provided an important demonstration of a left-hemisphere advantage in an animal whose rank in the evolutionary scale might have led one to expect a functionally symmetrical brain. But why nature should choose asymmetrical location for critical biological functions remains as mysterious as ever."
J.C.MARSHALL, 1987, Nature 325, 15 i.

"Our review [of handedness in non-human primates] reveals numerous statistically significant instances of hand use asymmetries at the level of population samples. All but one of the left-hand preferences were for reaching. Right-hand preferences were for manipulation and practised performance in stereotyped situations, among other things."
P.F.MacNEILAGE et al., 1987, Behavioral & Brain Sciences 10.

"I.P.Pavlov suggested and experimentally confirmed the conception of "dynamic stereotype" - a stable system of nervous processes which is formed in the human and animal cerebral cortex under the influence of repeated external stimuli.... [We] established that....novelty leads to predominant activation of the left hemisphere, and [that] during repetition of the activity the right hemisphere begins to predominate."
P.V.SIMONOV & M.N.RUSALOVA (USSR Academy of Sciences), 1988, to 24th International Congress of Psychology, Sydney (F715).

"....the intellectual development of the human race appears to be predicated on two events: an increasing specialization of labor between our two brain hemispheres (i.e. lateralization), and the ability to effectively integrate the products of each hemisphere's analyses."
Miles STORFER, 1989, Intelligence and Giftedness.
San Francisco : Jossey Bass.

"With the chicken brain as a model, research has revealed that brain asymmetry changes with age (we do not yet know whether it is ever static), that it can occur at many different levels of organisation in the brain, that it may or may not require left-right side intercommunication, and that its presence and/or direction is influenced by a complex intermingling of genes, hormones and the environment. No longer can we adhere to one cause to explain any sex differences in asymmetry which occur in the human brain."
Lesley ROGERS, 1989, 'The left and right of brains at work'.
New Scientist, No. 1651, 11 ii.

"....song....is primarily a function of the right cerebral hemisphere.... (1)....many elderly patients who have suffered cerebral haemorrhages in the left hemisphere - so that they cannot speak - still sing. (2) The so-called Wada Test is sometimes performed in hospitals to find out a person's cerebral dominance. Sodium amytal is injected into the carotid artery on one side, putting the corresponding hemisphere under heavy sedation but leaving the other awake and alert. When the injection is made on the left side so that the left hemisphere is sedated and only the right hemisphere is active, the person is unable to speak, but can still sing.... (3) Electrical stimulation of the right hemisphere in regions adjacent to the posterior temporal lobe....often produces hallucinations of singing and music."
Julian JAYNES, 1977 & 1990, The Origin of Consciousness in the
Breakdown of the Bicameral Mind
. Chicago : Houghton Mifflin.

"....the position, features and list order of visual objects are all handled by separate regions [of the prefrontal cortex]. Even more remarkably, a nearby region on the left side of this area appears to mediate discrimination of events closely spaced in time. Ninety per cent of dyslexic patients lack this ability, and cannot distinguish syllables differing only in their first 40 milliseconds, but the problem affects other senses as well. The lateralization of speech, rather than being uniquely human, may therefore an adaptation of previously existing neuronal circuitry, an idea supported by the recent demonstration that rats share the right ear advantage previously thought to be confined to humans."
R.SHORT, 1994, Nature 368, 14 iv, p. 583.

"Zaidel and others (Coltheart et al.) have formulated a profile of right-hemisphere language: reduced auditory-verbal short-term memory, better comprehension of speech than reading, and limited access to abstract words in the lexicon. Phonology in the right hemisphere is rudimentary so that rhyme judgements are poor, as are tasks requiring written word-to-sound (grapheme-morpheme) correspondence... the right hemisphere is thought to be "dominant" in such aspects of language as prosody - the variations in pitch, intensity, and rhythm that lend speech its "musical" quality. Furthermore, there is some evidence that the pragmatics of language, the appreciation of humour, metaphor and intended meaning, are curtailed following right-hemisphere damage. To summarise, there is convergence in the neuropsychological literature that the right hemisphere seldom has the ability to speak despite significant language comprehension capacity..... Females may not show such extreme lateralisation. This situation is important as it figures prominently in various psychiatric theories which nominate the right hemisphere as the origin of auditory hallucinations."
A.S.DAVID, 1994, 'The neuropsychological origin of auditory hallucinations.' In A.S.David & J.C.Cutting, The Neuropsychology of
Schizophrenia
. Hove, UK: Lawrence Erlbaum Associates.







(iii) How does lateralization (etc.) develop?


"My own theory of what happens when the cross-connections between these brain-halves [i.e. the cerebral hemispheres] are destroyed is that, in early life, we start with mostly similar agencies on either side. Later, as we grow more complex, combinations of genetic and circumstantial effects lead one of each pair to take control of both."
M.MINSKY, 1986, The Society of the Mind.
New York : Simon & Schuster.
|
"My own reading of the literature is that the basic anatomical asymmetries are present at birth and that a large number of functional asymmetries can be found at as early an age as we have reliable techniques to measure them."
J.C.MARSHALL, 1986/7.

"....we have previously stressed the importance of a fundamental left-hemisphere specialization for fine, sequential, temporal or analytic processing, and suggested that such mechanisms underlay both left-hemisphere language lateralization and a consistent general tendency to dextrality in human populations. Right hemisphere specializations were therefore seen as occurring by default. However, very recent evidence....indicates that domestic chicks have primitive right-hemisphere mediation of spatial processing and the automatic release of emotional behaviour, somewhat analagous to what is reported for humans, with (possibly higher-level) control by the left hemisphere of behaviours in the context of learning and discrimination."
H.K.BRADSHAW & N.C.NETTELTON, 1988, to 24th International
Congress of Psychology, Sydney (S906).

"....language experience can grossly alter cerebral development - and....if it is severely deficient, or otherwise aberrant, it may delay the maturation of the brain, preventing proper left hemisphere development, in effect confining the person to a right hemisphere sort of language [e.g. Curtiss, 1977, Genie; Neville, 1989]."
Oliver SACKS, 1989, Seeing Voices: A Journey into the World of the Deaf. Berkeley, CA : University of California Press.

"....if {as hypothetically in mental handicap} the developmental process is slowed or arrested, there would be a lack of differentiation [of handedness, cf. Palmer, 1964, Psychol. Bull.], and experiences may then be more important in deciding handedness than biological factors."
J.LEWIN, D.KOHEN & G.MATHEW, 1993, 'Handedness in mental handicap: investigation into populations of Down's syndrome, epilepsy and autism'. British Journal of Psychiatry 163.

"....variations in female sex hormones have different and generally opposite effects on tests which differentiate males and females. The articulatory, complex manual, verbal fluency and some perceptual speed tests, on which women are superior to men, generally showed enhancement in the high oestrogen phase [of the menstrual cycle, 5-10 days prior to menstruation]. Tests of spatial ability showed the reverse effect.... ....In humans, we know that fluctuations in estrogen may be associated with alterations in functional brain asymmetry, with left-hemisphere activity relatively enhanced during higher levels of estrogen. Since this is a reversible effect, one might speculate that it is achieved by changing interhemispheric inhibition...."
Doreen KIMURA & Elizabeth HAMPSON, 1993. 'Neural and hormonal mechanisms mediating sex differences in cognition.' In P.A.Vernon, Biological Approaches to the Study of Human Intelligence. Norwood, NJ : Ablex.


"[How late can lesions happen while still permitting re-organization of the brain to take place?] ....a child....sustained left hemisphere damage in utero and enjoyed normal development up to age seven when she started having seizures. At age ten the left hemisphere was removed, but there appeared to be no effect on language functioning and she was able to attend school and take normal examinations."
From a summary of a paper by Dr Faraneh Vargha-Khadem, read to
Academia Rodinensis Pro Remediatione, ix 1994.

"Annett has long subscribed to the notion that the advantage of the right hand for motor skill is due to "something that weakens the left hand." In support of such theorizing, Kilshaw & Annett (1983) investigated hand skill for peg moving as a function of degree of hand preference and found that, irrespective of hand dominance, there was a strong linear trend towards slower peg moving for the non-preferred hand with increasing degree of right-handedness. This finding was particularly evident in females. Moreover, Annett & Manning (1986) reported a similar pattern using a more detailed breakdown of subjects along the left/right hand preference continuum. In composite, such findings suggested to Annett "that strong dextrality depends on a process which induces left hand weakness, probably associated with impairment of right hemisphere function" (Annett, 1995)."
M.W.O'BOYLE, 1995, Cahiers de Psychologie Cognitive 14.
|
"Although our sample [of 80 students {doing a repetitive finger tapping task}] is not representative of the general population, Annett's suggestion that the typical advantage of the right hand is due to a weakened left hand is not supported."
J.W.Van STRIEN, 1995, Cahiers de Psychologie Cognitive 14.


(iv) The functional significance of lateralization, R-vs-L localization, 'dominance', and interplay.


"Why [the right hand] was chosen is a question not to be settled, not worth asking except as a kind of joke."
Thomas CARLYLE.

"Bilateralisation of function arose in response to specifically human pressures, occurring in a socially organised species, the members of which were mutually interdependent."
Jerre LEVY, 1977, Annals of the New York Academy of Science 299.

"The subjective unity of self, of thought and of personal experience is an illusion created by the limited capacity of self-awareness systems and their need to process information sequentially. The illusion is enhanced, in our model, by the suppression of the self-awareness system in one hemisphere by its partner in the other hemisphere."
D.A.OAKLEY & L.C.EAMES, 1985, in D.A.Oakley,
Brain and Mind. Oxford : Blackwell.

"R.Swinburne (1986, The Evolution of the Soul) would "explain" the problem generated by the behaviour of "split-brain" patients as "the problem of discovering the number of souls connected to a given brain."
D.M.MacKAY, 1986, Nature 323, 23 x.

"An obvious starting point [in theorizing about the evolution of handedness] is the reputation of the left hemisphere for time-sequencing - not just for bilateral motor sequencing of hand and face, but for detecting sensory sequences as well. Sequencing suggests specialized buffering such as when a ballistic movement must be planned in advance and then rapidly executed without benefit of further sensory feedback (e.g. when a sequence of sounds must be held and analyzed while determining phoneme and word order).... timing tasks should be especially prone to lateralization because of the slow conduction through the callosum, which would make co-ordination of two centers [in the two separate hemispheres] impossible for brief time frames."
W.H.CALVIN, 1987, Behavioral & Brain Sciences 10.

"It is the demand for precision in timing....that appears to have shifted the hand preference from the left in monkeys to the right in humans."
M.A.GOODALE, 1987, Behavioral & Brain Sciences 10.

"Human handedness is secondary to language."
S.WALKER, 1987, Behavioral & Brain Sciences 10.
(Re-iterating a conclusion that he had first drawn in 1980.)

"The brain is adapted to create and maintain human society and culture by two complementary conscious systems. Specialized motives in the two hemispheres generate a dynamic partnership between the intuitive, on the one side, and the analytical or rational, on the other side, in each person....
The {many} precautions needed to reveal divided awareness after brain bisection emphasize how, in normal active life, information about the world is constantly reflected to all parts of the brain as it and the body engage in changing relations with the external world. It does not appear necessary to imagine that the 'self', which has to maintain a unity, is destroyed when the forebrain commissures are cut, although some of its activities and memories are depleted after the operation."
C.TREVARTHEN, 1987, in R.Gregory, The Oxford Companion
to the Mind
. Oxford University Press.

"....when a person is driving, he or she systematically scans the environment, not simply shifting attention to a single place but setting up a sequence of such shifts. Indeed, when the driver notices something, the scan pattern may have moved on, and he or she will do a double take, returning to the point of interest. In such cases, one does not want to have to co-ordinate corresponding operations on the two sides of the brain. That is, a search path can cross the midline and hence fall under the purview of the contralateral hemisphere. But one does not want each hemisphere to have its own agenda; one wants a co-ordinated search plan extending across the entire field.... Thus, it is not surprising that, in most right-handed males, one hemisphere - typically the right - appears to have a special role in controlling visual search (e.g. De Renzi, 1982)....
We have evidence that the two hemispheres have different facility in computing categorical and co-ordinate representations of spatial relations.... When a categorical representation can be used [e.g. for 'The dot is on/off the line'], the left hemisphere is better; when a co-ordinate representation is more useful [as for 'The dot is greater/lesser than 2mm. from the line'], the right hemisphere is better."
S.M.KOSSLYN, 1987, Psychological Review 94.

"[N.D.Cook's] theory is based on the twin assumptions that the corpus callosum interconnects homotopic cortical columns, and that the fundamental mode of action of this structure....is inhibitory. Activation of a cortical column in, say, the left hemisphere, gives rise to inhibition of a homotopic column on the right side, but to excitation of immediately surrounding columns because of the release from "surround inhibition".... understanding a word is assumed to occur via excitation of a single cortical column corresponding to the word's denotative meaning in the left hemisphere, and, in the right hemisphere, via excitation of a population of columns surrounding the inhibited homotopic column to provide the connotative meaning.... [Cook uses] the metaphor of an "executive" left hemisphere acting under the supervision of a "board of directors" in the right hemisphere. He further argues that the respective abilities of each hemisphere are an important factor in determining personality differences between individuals, and are amenable to psychometric measurement. Such ideas have been the subject of trenchant criticism, on both conceptual and methodological grounds, from J.G.Beaumont and colleagues (Cognitive Neuropsychology 1)."
Michael RUGG, 1987, Nature 325, 26 ii.

"We conjecture that, in the evolution of the brain, there are two opposite tendencies. The first promotes inter-hemispheric asymmetry and specialization.... At later stages of evolution, there emerges a second tendency: a decrease in morphological asymmetry and an increase in functional asymmetry as a result of intensive development of interhemispheric co-operation."
I.I.GLEZER, 1987, Behavioral & Brain Sciences 10.

"Does the [split-brain] operation split the self in two? After it, patients normally exhibit no sign of psychological splitting, appearing to be no less unified than you or I except under particularly contrive circumstances. But, on [Michael] Gazzaniga's view, this does not so much show that the patients have preserved their pre-surgical unity as that the unity of normal life is an illusion."
Daniel C. DENNETT, 1988, Times Literary Supplement, 16-22 ix.

"Humans show a distinctive pattern of laterality that is not shared by other primates. The most obvious components are right-handedness and the left-cerebral control of language. It is suggested that these are manifestations of a more general left-hemispheric specialization for the generation of cognitive representations, in hierarchical fashion. Human language appears to have a uniquely generative aspect, and recent evidence....suggests that the left hemisphere may be specialized for the generation of images, including images of visual shapes and word sounds."
M.C.CORBALLIS, 1988, to 24th International Congress
of Psychology, Sydney.

"The evidence available from studies looking at each [brain] hemisphere's view of itself points to a large degree of unification and consistency. Probing the values and beliefs of each separated hemisphere in one young man revealed high concordance except for career choice, where the left hemisphere chose "draftsman" while the right preferred "automobile racer". Indeed, the strategy of having one hemisphere play the other at chess failed to produce dramatic conflict. It seems that we may have to draw a distinction between having two potentially independent cognitive systems and having two selves."
A.S.DAVID, 1989, British Journal of Psychiatry 154.

"....if the essential higher cognitive function of the right hemisphere (RH) is to build and maintain cognitive "frameworks" (to which the LH sends its literal, denotative language and from which LH receives contextual guidance), the first elements in a central dogma for human psychology can be expressed as the flow of information (1) between the right and left hemispheres;
(2) between the "dominant" LH and the peripheral mechanisms used for verbal communication."
N.D.COOK, 1989, New Ideas in Psychology 7.
¦
"....even if Cook's characterisation should prevail in the case of language, it remains an open question whether or not the same "dogmas" and "axes" would obtain with other symbol systems, modules or intelligences."
Penny PRATHER, H.GARDNER & H.H.BROWNELL, 1989,
Philosophical Transactions of the Royal Society.

"It must be concluded that the costs of left hemisphere specialization are not just to right-hemisphere functions but to overall brain power, that is, general intelligence."
Marian ANNETT & Margaret MANNING, 1989,
British Journal of Psychology 80.

"The idea of a duality between the hemispheres was prompted by the discovery of right-hemispheric superiority for certain skills in commissurotomized patients and was a necessary corrective to the earlier notions of the left hemisphere as the major hemisphere.... However, the reaction may have gone too far, with the right hemisphere achieving even a cult status (e.g. R.E.Ornstein, 1972, The Psychology of Consciousness).... A more dispassionate view of the right hemispheric specialization suggests that it is never so marked as the left-hemispheric dominance for speech, and that it tends to be relative rather than absolute. Right-hemispheric superiorities typically apply to rather elementary functions.... [My own account] relates closely to the idea that the left hemisphere is specialized for analytic processing (e.g. Bradshaw & Nettelton, 1981, Behav. & Brain Sciences 4)....; [but] I have stressed not the analytic aspect of left-hemisphere processing so much as its converse - the ability to construct representations from parts rather than the ability to dissect into parts."
M.C.CORBALLIS, 1989, 'Laterality and human evolution'.
Psychological Review 96.

Among the more widely recognized diagnostic criteria [for schizophrenia] are the 'first rank' symptoms identified by Kurt Schneider. ....these are:
1. Hearing one's thoughts spoken aloud within one's head.
2. Hearing voices arguing.
3. Hearing voices that comment upon what one is doing.
4. Experiences of bodily influence (that bodily functions are affected by an outside agency.
5. Experiences that one's thoughts are being withdrawn from or inserted into one's head.
6. Thought diffusion, or the experience that one's thoughts are broadcast to others.
7. Delusional perception (the attribution of special significance to a particular perception), and
8. Feelings or volitions experienced as imposed on the patient by others.
....all can be summarized by the basic idea that in the schizophrenic brain the unintegrated right-hemisphere consciousness may become an 'alien intruder' on the verbally expressive left hemisphere. In other words, they are prototypical of what one might expect were interhemispheric communication so distorted that the left hemisphere could no longer identify the origin of activities in the right hemisphere as belonging to the unified consciousness of the self."
R. W. DOTY, 1989, 'Schizophrenia: a disease of interhemispheric processes at forebrain and brainstem levels?' Behavioural Brain Research 34.

"Lack of cerebral dominance may underlie language disorders such as dyslexia and stuttering."
M.C.CORBALLIS, 1995, Nature 377, 2 ii.

"....the original evolutionary pressure towards hemispheric specialization may have had nothing to do with language and handedness. Perhaps the imperative was the visuospatial requirement of knowing your own territory and being able to find your way home reliably."
J.F.STEIN, 1995, Cahiers de Psychologie Cognitive 14.

"Ringo et al. (1991, Exptl Brain Rs 86; 1994, Cerebral Cortex 4) suggest that as the brain increases in size there is a corresponding fall in the percentage of connectedness. They plausibly argue that if the percentage of connectedness is to be maintained in the face of increased neuron number, then a large fraction of any brain size increase would be spent maintaining such interconnections while the increasing axon length would reduce neural computational speed. Thus, larger brains would necessarily be limited in allowable interconnectedness, and hence would tend to show more specialization."
L.JÄNCKE, 1995, Cahiers de Psychologie Cognitive 14.

"[Arguably] images are built up by arranging parts and....two different processes can be used to arrange them. Once process uses stored descriptions to arrange parts, and is more effective in the left cerebral hemisphere; the other process uses stored memories of metric positions to arrange parts, and is more effective in the right cerebral hemisphere."
S.M.KOSSLYN et al., 1995, Neuropsychologia 33.



(v) Individual differences in lateralization
etc. and their possible relation to personality differences.


"In general, we suspect that disorders of personality or psychosexual development, if related at all to laterality, are the products rather than the causes of left-handedness or left-right confusion."
M.C.CORBALLIS & I.L.BEALE, 1976, The Psychology
of Left and Right
. New York : Wiley DePublisher.

"Field-independent and field-dependent people have different brain organization - we know this now."
E.ZAIDEL, 1979, to a NATO Conference on Intelligence and Learning.

"....there is a possibility of finding a biological basis for [H.J.Eysenck's dimension of] Psychoticism in the unusual integration of the brain's two hemispheres that has sometimes been observed in schizophrenics (see Tress & Kugler, 1979 {see Quotes XV}). Additional if indirect evidence for associating P with unusual brain organization is provided by the higher rates of mixed-handedness to be found in psychotic young men (Lishman & McMeekan, 1976), juvenile delinquents (Findlay, 1979), and, indeed, high-P scorers (Birrell, 1978)."
C.R.BRAND, 1981, in R.Lynn, Dimensions of Personality.
Oxford : Pergamon.

"All in all, there seems little cause at the moment to give up the hypothesis that left-handers differ from right-handers solely by virtue of preferring their left hands."
J.MARSHALL, 1981, in Y.Lebrun & O.Zangwill,
Lateralization of Language in the Child.

"....in two studies, Standage and his colleagues [e.g. 1983, Brit. J. Psychiatry] found a higher than average incidence of mixed handedness in patients with personality disorders, especially female hysterics."
G.CLARIDGE & P.BROKS, 1984, 'Schizotypy and hemisphere function I'.

"Creativity has been hypothesized to involve the use of primary-process cognition, and such cognition is hypothetically accompanied by activation of the right cerebral hemisphere. In the light of these hypotheses, we predicted that highly creative people should exhibit greater right-hemisphere than left-hemisphere EEG activity during creative performance.... All three experiments supported this prediction."
C.MARTINDALE et al., 1984,
Personality & Individual Differences 5.

"....it seems that in almost any group that differs from the norm, one finds an increased incidence of left-handedness."
P.COREN, 1985, American Journal of Psychology.

"Among extremely mathematically and/or verbally precocious students [the top 1 in 10,000 in such reasoning abilities], the following three physiological characteristics were found at high frequencies:
left-or mixed-handedness; asthma and other allergies; and myopia.
The first two of these may reflect the effects of a common influence (testosterone) on the nervous and immune systems during fetal development. Moreover, our results suggest that such highly able students may exhibit bihemispheric representation of cognitive functions."
Camilla P. BENBOW, 1986, Neuropsychologia 24.

"Contrary to expectation, perceptual asymmetry on the word test decreased with recovery [from schizophrenia and depression], while asymmetry on the tone and dot tests did not change. Results cut across diagnosis, could not be related to medication, and were independent of changes in overall performance.... existing models and concepts are inadequate to explain the findings."
B.E.WEXLER, 1986, British Journal of Psychiatry.

"[The present] findings indicate that masculine men tend to evidence more relative right-hemisphere activation (via left hemisphere de-activation); whereas feminine women evidence a more bilateral pattern of activation.... certain aspects of hemisphere lateralization may be mediated by various experimental factors (e.g. sex role socialization)."
K.A.BERFIELD et al., 1987, Neuropsychologia 24.

"....sex and twinning are associated with variations in the expression of the right shift factor (and the hypothesized rs+ gene), such that females are more strongly right-shifted than males, and the singleborn than twins. These differences, which have been inferred from hand preference data for some years, have recently been demonstrated in data for hand skills, in twins and singleborns of each sex, in the National Childhood Development Survey. Male sex and twinning are both associated with lesser maturity at birth. Similarly the fewer consistent right-handers among dyslexics and homosexual males (J.Lindesay, 1987, Neuropsychologia 25) could be due to any factor which impeded the normal expression of the rs+ gene, probably as it influences cerebral maturation in late fetal or perinatal life."
Marian ANNETT, 1988, Neuropsychologia 26.

"According to Dr Robert Hare {University of British Columbia} who has studied psychopaths for twenty years, the left hemisphere of the brain, which normally controls language, is less highly developed in psychopaths. Clinical tests have proved that their neurological reaction to language is split between the right and left hemispheres and is thus impaired. In effect, although psychopaths can understand the dictionary meaning of a word, it has no emotional impact. 'Psychopaths use a lot of jargon words. They use words that for most of us would be emotional words like "I love you". But there doesn't seem to be an emotional effect, there is no real meaning,' says Dr Hare."
Kevin TOOLIS, 1988, The Observer Magazine, 10 i.

"Better interhemispheric transfer performance [matching stimuli across the body midline] by non-right-handers and by females may be related to the reportedly larger corpus callosum regions in these groups and also to the reportedly less strong lateralization of function."
Susan M. POTTER & R.M.GRAVES, 1988, Neuropsychologia 26.

"The evidence in support of interhemispheric disturbances in schizophrenia does not suggest a total disconnection between the two hemispheres (akin to a functional split-brain condition) but rather a partial disconnection or malconnection.... In general, in the normal brain, a full integration between the two hemisphere systems would lead to coherent exchange of thoughts, feelings, perceptions, cognitions and intentions, resulting in an overall unity of the two spheres of activity and consciousness. In the disintegrated brain, this overall unity is degraded, raising the possibility that each hemisphere might to some extent regard the other as being 'not-of-the-self'....
The above model would predict....that first-rank [schizophrenic] symptoms could not be present in a fully integrated or a totally disconnected interhemispheric system. It is of some interest, then, that both Laitenin (1979) and Wilson et al. (1982, Neurology 32) report that partial sectioning of the corpus callosum alleviated schizophrenic symptoms in two patients. The model is further bolstered by the observations that there are no reported accounts of such symptoms in split-brain patients, in individuals with callosal agenesis, or in cases of right hemispherectomy."
M.BIRCHWOOD et al., 1988, Schizophrenia. London : Longman.

"People with a dominant left hemisphere [should, according to present theories] be better able to control their emotions. It is furthermore interesting that a connection has been found between [right] cerebral dominance and hypnotic susceptibility.... That right hemispheric dominance leads to a greater field dependence has been known for some time. Levy, partly relying on Charman's (1979, Cortex) work, claims that there is also a connection between cerebral dominance and personality traits such as introversion-extraversion."
W.BUIKHUISEN et al., 1988, in W.Buikhuisen & S.A.Mednick,
Explaining Criminal Behaviour. Leiden : E.J.Brill.

""Positive symptoms" [of schizophrenia] (i.e. hallucinations and delusions) were associated (in a study of 26 newly hospitalized acute patients) with normal asymmetries (of hemisphere function); whereas negative symptoms (flattened affect, withdrawal) were associated with absence of symmetry. Antipsychotic drugs tended to eliminate lateral asymmetry...."
V.CARR & Jo WALES, 1988, to 24th International Congress
of Psychology, Sydney (F275).

"[Our] 'left-brained' group was composed predominantly of individuals who were introverted, relied primarily on the senses for perception {according to the Myers-Briggs Type Indicator}, and preferred using a judgement process for dealing with their external environment.... this association does suggest that the underlying tendencies for hemisphericity stem from deep-seated attributes rather than peripheral or malleable performance tendencies. Perhaps personality and hemisphericity are both reflections of a larger determining factor, or perhaps one determines the other."
Deborah L.CROSSMAN & J.POLICH, 1989,
Personality & Individual Differences 10.

"A main purpose of this study [of 102 left-handed writers and 102 right-handed writers at a junior college in a Stockholm suburb] was to analyze cognitive neuropsychological differences between right- and left-handers, taking sex differences into consideration. The results indicated that hand preference was not associated with neuropsychological differences, across sex, or in interaction with gender. Only small and scattered differences in test performance emerged between right- and left-handers. In contrast, there were numerous and pronounced differences in performance between males and females."
Maria LEVANDER, S.E.LEVANDER & Daisy SCHALLING,
1989, Intelligence 13.

"Individuals can be categorized by whether they use the right or left hemisphere relatively more than others. A simple way of doing this is to face a [right-handed] person and ask questions and note which way his eyes move as he thinks of an answer.... It has been reported that people who, in answering questions face to face, turn their eyes to the left, who are thus using their right hemisphere more than others, are much more susceptible to hypnosis."
Julian JAYNES, 1977 & 1990, The Origin of Consciousness in the Breakdown of the Bicameral Mind. Chicago : Houghton Mifflin.

"Arithmetic skill [in 150 representative British children] was strongly associated with the skill of the left hand, even when intelligence and motor skill were controlled. This suggests that arithmetic ability, even in the primary school years, must have some special dependence on the right hemisphere."
Marian ANNETT & Margaret MANNING, 1990, Neuropsychologia 28.

"In the present investigation, the average-ability youths exhibited the prototypical right eye / Left Hemisphere advantage for the presentation of dichotically presented consonant-vowel syllables; while the precocious subjects [in the top 0.5% for intellectual ability as measured by Scholastic Aptitude Test] failed to demonstrate any ear / hemisphere advantage on the task. The absence of asymmetry in the gifted group was due to the surprisingly successful performance of the Right Hemisphere in the processing [by the gifted] of linguistic stimuli."
M.W.O'BOYLE & Camilla BENBOW, 1990, Neuropsychologia 28.

"[Our] study contends that males with the fragile-X syndrome feature problems in the visuospatial sphere as compared with Down's syndrome males matched on vocabulary ability.... It is possible that the deficit in non-dominant hemisphere functioning may be a pathognomonic feature of the chromosomal abnormality."
S.F.CROW & D.HAY, 1990, Neuropsychologia 28.

"There has been, in recent years, increasing medical interest in the relation of left-handedness to various neurological conditions and immune disorders, due mainly to the work by Norman Geschwind and Albert Galaburda.... A total of 437 cases of [migraine, cluster headaches and tension headaches] were studied.... Chi square tests did not show any significant difference [of any group from the normal (10%)] in the frequency of left-handedness. The lack of association between migraine and left-handedness has been noted earlier by Blau (1985, Lancet)."
H.B.MESSINGER et al., 1988, Cephalalgia 8,
as abstracted in ?Medical Monitor, 1991.

"....we found a tendency towards left-handedness in [325 allergy] patients whose allergic symptoms started before puberty.... [An explanation] is suggested by Geschwind's theory, where the association between sinistrality and allergy would result from a developmental defect of both the brain and the thymus during ontogenesis."
Catalina BETANCUR et al., 1990, Neuropsychologia 28.

"The relation between brain activity and the immune system was evaluated by assessing immune responses in twenty healthy women who manifested extreme differences in the asymmetry of frontal cortical activation.... As predicted, women with extreme right frontal activation had significantly lower levels of natural killer cell activity...."
Duck-Hee KANG et al., 1991, Behavioral Neuroscience 105.

"If spatial sex differences were selected for because they maximized the effectiveness of division of labor, then it would follow that sex differences in lateralization emerged as a consequence.... [in our model] males are not regarded as more highly specialized than females {who are actually found to have superior memory for spatial configurations and locations}, but differently specialized."
I.SILVERMAN & Marion EALS, 1992, in J.H.Barkow, Leda Cosmides & J.Tooby, The Adapted Mind. New York : Oxford University Press.

"....the prevalence of frontal left hemisphere activity in focused arousal and selective and discriminative mechanisms increases with the level of extraversion."
V. DE PASCALIS, 1993, Personality & Individual Differences 14.

"[Physiological correlates of extreme mathematical talent] include left-handedness, immune disorders, myopia and enhanced right-hemispheric functioning.... During spatial processing....gifted males demonstrat[ed] the capacity to selectively inhibit regions of the left hemisphere and thereby allow the right hemisphere to predominate in the processing."
Camilla BENWBOW & D.LUBINSKI,1993, in Ciba Foundation Symposium 178, The Origins and Development of High Ability. Chichester : Wiley- Interscience.

"Reading ability is higher in children at the centre of the right-left handedness continuum than at both extremes. Annett (1993, Brit. J. Dev. Psychol.) has shown that educational success in public examinations at 12 years and at 16 years was more frequent in {mixed-handers}."
Marian ANNETT, 1994, Behavior Genetics.

"Numerous teams have....found that the structural and functional abnormalities in the brains of schizophrenics tend to be concentrated in the left hemisphere."
Phyllida BROWN, 1994, New Scientist, 9 vii.

"The two hemispheres of the brain become more different and more specialized in boys. The corpus callosum, which connects the two, grows larger in girls. It is as if testosterone has begun to isolate the boy's right hemisphere from the colonization by verbal skills from the left. ....Language seems to come into the brain like an invading Goth, taking the place of other skills, and testosterone appears to resist this."
Matt RIDLEY, 1994, The Red Queen: Sex and the Evolution of Human Nature. Harmondsworth, UK : Penguin.

"The left and right hemispheres are divided into frontal and basal regions. Known as the four quadrants of the brain, each has its own characteristics {according to American psychologist Dr Katherine Benziger}. 'Dependable conservative types who enjoy routine are dominated by the left basal quadrant whereas people who are naturally intuitive, emotional and empathetic are dominated by the right basal.' Right frontals are creative and imaginative, tending to think in pictures rather than words, left frontals are logical, analytical and good at making decisions.... Benziger's clients include IBM, Shell and Du Pont. 'In most companies, the power is held almost entirely by the left frontals....left basals are middle managers....right basals oil the works and look after the boss....right frontals are the mavericks..."
Rita CARTER, 1995, Sunday Telegraph (Magazine), ii.

"The idea [of Gangsted & Yeo, 1995, Neuropsychology 8] is that polygenic homozygosity [for handedness] leads to developmental instability as manifest in a host of developmental disorders, including schizophrenia, autism, hyperactivity, dyslexia, certain physical anomalies, and susceptibility to pathogens, and it is also expressed as a deviation in either direction from the species-typical pattern of moderate right-handedness. Consistent with their theory, but contrary to what Annett and McManus would predict, Gangsted & Yeo present evidence that extreme right-handers as well as extreme left-handers have a raised proportion of left-handed parents. ....[Another] possibility is that the handedness gene might be localized in an X-Y homologous region of the sex chromosomes (cf. Crow, 1993, Lancet 342). If this were so, then one might expect heterozygous fathers to pass on a particular allele either to their sons or their daughters, but not to both. ....there is a real sense of progress, which I hope will not become mired in dogma or excessive polarization of views."
M.C.CORBALLIS, 1995, Cahiers de Psychologie Cognitive 14.

"Marian Annett's theory....provides a powerful conceptualization of individual differences in pattern of brain organization. We have found that the application of her theory to our own research has produced a rich body of data. ....[E.g. among 218 fourth-graders the mean IQs] were 110, 114 and 109 for the non-right-handers, the moderate right-handers and the strong right-handers respectively, with an effect size of .33."
M.Beth CASEY, 1995, Cahiers de Psychologie Cognitive 14.

"[In] two experiments using the dichotic shadowing technique....high Psychoticism scorers [failed] to show the right-ear superiority shown by the low P scorers....Hare & McPherson (1984) found that a group of criminal psychopaths showed a significantly smaller right-ear advantage."
H.J.EYSENCK, 1995, Genius: the Natural History of Creativity. Cambridge University Press.

"Modern work increasingly invokes some kind of suppression of one hemisphere by the other (e.g. Cook, 1986; Benbow & Lubinski, 1993). Such distinct suppressive processes might yield the greater consistency of lateralization found in females; and their occasional relaxation might account for the female tendency to exhibit multiple personality disorder and 'spirit possession' (Spanos, 1994). By contrast, males show more specialized lateralization of function (McGlone, 1977): this allows suppression not of anything like a whole 'personality' but rather of particular functions. Notoriously such male suppression may be applied to conscience-i.e. to the superego-like "board of directors" (Cook, 1986; Badcock, 1994) that detects and tries to enforce regularities on the "executive" ego. Such more closely targeted suppression of particular functions could explain the extreme and 'bipolar' moods of the acute psychotic disorders to which males are more prone (Cutting, 1990). The idea would be that there is more suppression in females but more effect on specific functions in males."
C.R.BRAND, 1995, Cahiers de Psychologie Cognitive 14.


"....there may be some substance in the early adumbrations implicating the left hemisphere in support of theories of lateralized tempero-limbic abnormalities in schizophrenia (Flor-Henry, 1969....). ....There is more clear-cut evidence if right-hemispheric (or non-dominant) impairment in patients suffering from manic-depressive disorder. A recent review of 25 such studies (Goodwin & Jamison, 1990, Manic-Depressive Ilness, OUP) disclosed a quite consistent pattern of such impairment. Are these data related to psychoticism? Kidd & Powell (1993, PAID 14), using schizotypy tests, have shown that subjects with high schizotypy scores tended towards left hemisphericity and exhibited considerably less bilateral alpha power in the EEG than those with lowered schizotypy scores. 'This is interpreted as offering tentative support for a left hemisphere overactivation hypothesis of psychotic experience.' It will be evident that no clear-cut conclusion emerges from all these studies. Laterality may be connected with psychoticism and creativity, but it would need much more targeted research to make such an hypothesis tenable."
H.J.EYSENCK, 1995, Genius: the Natural History of Creativity. Cambridge University Press.

"[Dr Frank Corrigan, a Scottish expert on Attention Deficit Hyperactive Disorder (ADHD)] is heartened by findings....that show abnormalities in the brains of hyperactive children. "Brain imaging of children with ADHD shows...right lobe asymmetry. In hyperactive children, the right side of the brain appears to be smaller.""
Jean WEST, 1996, The Scotsman, 30 x.








(vi) Developmental origins (in 'nature' or 'nurture') of individual differences in lateralization.


"There is in fact very little evidence that genetic variation plays any significant role in causing variations in human laterality."
M.J.MORGAN & M.C.CORBALLIS, 1978.

"This paper demonstrates that the distributions of left-handedness in all the large studies of family handedness are predictable from the right-shift theory of handedness on the assumption that the shift depends on a single gene.... The slowing of early growth in twins may handicap the expression of cerebral asymmetry."
Marian ANNETT, 1978, A Single Gene Explanation of Right and Left
Handedness and Brainedness
. Coventry : Lancaster Polytechnic.

"Annett's right-shift model of the distribution of skill asymmetry, and of the genetics of handedness is....found to be a less adequate description than is the more intuitively obvious 'symmetric bimodal' model...."
I.C.McMANUS, 1985, British Journal of Psychology 76.

"The claim that the right-shift theory fails is examined and rejected on several grounds.... the common-sense classification into left- and right-handers, although undoubtedly the starting point of all analyses of laterality, including that of the right-shift theory, has led to little progress in the search for the causes and consequences of lateral asymmetries. The classification can lead to sterile arguments about the 'true' incidence of left-handedness, of which examples are to be found in McManus's paper."
Marian ANNETT, 1985, British Journal of Psychology 76.

"Laterality research is unfortunately prone to misapplying complex statistics and producing wrong or uninterpretable findings."
I.C.McMANUS, 1987, Behavioral & Brain Sciences 10.

"The linear subgroup hypothesis [of seven main handedness groups] was considerably more powerful than a classification into two discrete groups, right-handers and left-handers.... Models of the genetics of handedness based on a discrete, binary classification of handedness (Levy & Nagylaki, Genetics 72, 1972; McManus, 1985, Psychol. Med. Monogr. Suppl. 8) cannot account for these findings."
Marian ANNETT, 1994, Behavior Genetics.

"The inability to form a holistic picture of a complex situation, poor powers of reality testing and impaired real world knowledge, the decreased ability to perceive spatial information, the difficulties in labelling emotions expressed in pictures of human faces, the disintegration of non-verbal behavior - all these symptoms [of schizophrenia] are related to right-hemisphere dysfunctions.... [I} agree with Cutting (1990, The Right Cerebral and Psychiatric Disorders, O.U.P.) that the basic dysfunction in schizophrenia is localized in the right hemisphere.... From [my] point of view, it is an inability to [process] a polysemantic context and as a result to create a polydimensional self-image as an integrative unconscious regulator of behavior, which determines the activity of the psychological defense mechanisms.... right-hemisphere insufficiency, determined by the peculiarity of early emotional relationships, produces a general predisposition to the schizophrenic disorders [especially their 'negative' symptoms - of poverty of thought and affect]. However, if the ability to form and manage the polysemantic context is lost....[a patient may make] attempts to compensate [for] his right-hemisphere defect by left-hemisphere overactivation.... [Here] the left hemisphere is able to create an artificial explanatory system, self-determined, managed by formal logical rules and disconnected from reality.... This artificial system is a basis for delusions and hallucinations."
V.S. ROTENBERG, 1994, 'Brain hemisphere functions in schizophrenia: a systemic psychodynamic approach.' Dynamische Psychiatrie 26.

"The fact that variation in handedness can be explained without positing that it reflects genetic variation is demonstrated by Laland et al. (1995, Behavior Genetics 25)."
K.L.LALAND, 1995, Cahiers de Psychologie Cognitive 14.
|
"The claim of Laland to have a better theory than [the right shift factor] is particularly interesting. First, it must be explained that Laland et al. (1995) collected no data themselves, but based their analyses on the Tables produced by McManus (1985). It may be inferred that they did not consult original papers because they reproduce errors in these Tables... [They develop a new model,] summarized as follows. "Variation in handedness among humans is generated by accidents of early development.... All our genes do is simply load the handedness die to favor the right." These are the essentials of the right shift theory .... [The right shift theory] is worth the attention so far expended. Laland et al., starting from different premises and with a different rationale have rediscovered it."
Marian ANNETT, 1995, Cahiers de Psychologie Cognitive 14.

"Twins of both kinds have a higher rate of left-handedness. Some scientists, like Luigi Gedda, the director of the Gregor Mendel Institute in Rome, have suggested that all left-handed singletons may be survivors of a vanished twin pair."
Lawrence WRIGHT, 1995, 'Double mystery.'
New Yorker, 7 viii.













Epilogue


"Split- and whole-brain studies have led to a new conception of human knowledge, consciousness and intelligence. All knowledge cannot be expressed in words, yet our education is based almost exclusively on the written or spoken word.... Many people whom we consider "unintelligent" or "retarded" may in fact possess a different kind of intelligence and may be quite valuable to society."
R.E.ORNSTEIN, 1985, Psychology: the Study of Human Experience.
San Diego : Harcourt Brace Jovanovich.

"Undoubtedly the field of neuropsychology has much to offer the study of intelligence and cognitive development."
F.N.DEMPSTER, 1989, Learning and Individual Differences 1.

"The left brain - right brain story, while giving rise to much creative scientific inquiry, has also spawned some rather dubious psychophantasy."
A.S.DAVID, 1989, British Journal of Psychiatry 154.

"Is emotion processed primarily in the right hemisphere, the left hemisphere, or both? Does it make any difference whether the emotion is positive or negative? After addressing these questions for several years, I have sadly concluded that the answers are by no means simple."
B.D.SMITH, 1991, Abstracts for International Society for
the Study of Individual Differences, Oxford.

"Interest in cerebral asymmetries was first awakened in the 1860's when Broca reported evidence of left cerebral dominance for speech, and a flurry of research and speculation ensued. Fantasy quickly overwhelmed fact.... In the 1960's, history repeated itself when R.W.Sperry carried out his Nobel-prize-winning studies of the so-called split brain patients, leading to the left brain \ right brain cult that is now ingrained in our folklore.... {Today} no single principle seems to capture the increasingly intricate findings, and J.B.Hellige (in Hemisphere Asymmetry, Harvard Univ. Press).... resorts to multiple models, a theoretical strategy that sometimes verges on tautology."
M.C.CORBALLIS, 1993, Nature 363, 24 vi.

"[Michael Corballis, professor of psychology at Auckland University and author of books like The Lopsided Ape] is a world authority on left-brain/right-brain functioning. Techniques that claim to make you smarter or more creative by accessing the right side of the brain or using the whole brain are "about five per cent true", says Corballis. "I think it's used more metaphorically than neurologically, frankly. Some of these techniques - claiming to draw with the right side of the brain, for instance - are probably teaching you how to draw, but I don't think they're necessarily getting into the right side of the brain. Those sorts of things are wild extrapolations about what we've found out about different sides of the brain.... ....[nor is there] evidence to suggest that the world can be divided into right-brain people and left-brain people. In EEG tests of brain activity, with lawyers presumed to be left brain and sculptors presumed to be right brain, researchers could find no overall difference between the two groups....Musical ability is said to depend more on the right brain than on the left hemisphere but, curiously, trained musicians show a left-hemispheric superiority in the recognition of melodies.... In studies of epileptic patients who have had their two hemispheres separated by surgery, there has been no loss of problem-solving ability or major change in intellectual function....nor does there appear to be any loss of that mysterious quality called creativity."
Noel O'HARE, 1995, 'Get smart.'
The Listener (New Zealand), 28 i - 3 ii.

"The difficulty in obtaining laterality effects at all, and particularly the failure to replicate findings across studies should be the focus of further research."
Halle D. BROWN & S.M.KOSSLYN, 1995
in R.J.Davidson & K.Hugdahl, Brain Asymmetry, MIT Press.






FINIS

(Compiled by C.R.Brand, Department of Psychology, University of Edinburgh.)

For coverage of general intelligence and other mental ability differences, see:
BRAND, C.R. (1996) The g Factor.
Chichester : Wiley DePublisher.

"The nature and measurement of intelligence is a political hot potato. But Brand in this extremely readable, wide-ranging and up-to-date
book is not afraid to slaughter the shibboleths of modern "educationalists". This short book provides a great deal for thought
and debate."
Professor Adrian Furnham, University College London.
The book was first issued, in February, but then withdrawn, in April, by the 'publisher' because it was deemed to have infringed modern canons of
'political correctness.'
It received a perfectly favourable review in Nature (May 2, 1996, p. 33).

For a Summary of the book, Newsletters concerning the
de-publication affair, details of how to see the book for scholarly purposes, and others' comments and reviews,
see the Internet URL sites:
http://laboratory.psy.ed.ac.uk/DOCS/crb/internet.html
http://www.webcom.com/zurcher/thegfactor/index.html

For Chris Brand's 'Get Real About Race!'-his popular exposition of his views on race and education in the Black
hip-hop music magazine 'downlow' (Autumn, 1996)-see:
http://www.bhs.mq.edu.au/~tbates/intelligence/Brand_downlow.html




A reminder of what is available in other Sections of 'P, B & S.'
Summary Index
for PERSONALITY, BIOLOGY
& SOCIETY

(This resource manual of quotations about individual and group differences, compiled by
Mr C. R. Brand, is kept on the Internet and in Edinburgh University Psychology Department Library.)
Pages of Introduction
3 - 11 Full Index, indicating key questions in each Section.
12 - 14 Preface. - Why quotations? - Explanations and apologies.
15 - 51 Introduction: Questions, Arguments and Agreements in the study of Personality.
-
Some history, and a discussion of 'realism vs 'idealism.'
52 - 57 Introductory Quotes about the study of personality.
Sections
General problems
1 'Situational' vs 'personological' approaches to human variation.
2 'Nomothetic' vs 'idiographic', 'subjective' and relativistic approaches.
3 Personality dimensions-by factor analysis and otherwise.
4 'Superstructure' and 'infrastructure.' - The 'mind/body problem'.
5 Nature versus Nurture? - Or Nature via Nurture?
6 The role of consciousness in personality and 'multiple personality'.
7 The 'folk psychology' of personality components.
Intelligence
8 The measurement of intelligence. - Does g exist?
9 The bases of intelligence. - What is the psychology of g?
10 The developmental origins of g differences. - The nature and nurture of g.
11 The importance of intelligence. - The psychotelics of g.
12 Piagetianism: Kant's last stand?
13 Cognitivism: 'The Emperor's New Mind?'
Propensities
14 Neurosis, emotion and Neuroticism.
15 Psychosis, psychopathy and Psychoticism.
16 Crime and criminality.
17 Genius and creativity.
Popular proposals - psychoanalytic, phrenological and prophylactic
18 Psychoanalysis: 'Decline and Fall of the Freudian Empire'?
19 Hemispherology: a twentieth-century phrenology?
20 Psycho-social Engineering: therapy, training or transformation?
Group differences
21 Age and ageing - especially, the role of g in 'life-span development'.
22 Psychological sex differences. - Do they exist? Must they exist?
23 Social class. - Does it matter any longer?
24 Racial and ethnic differences. - Their role in 'lifestyles' and cultural attainments.
Ideological issues
25 The psychology of politics and ideological extremism.
26 The politics of psychologists and allied co-workers.
27 Equality and Community: the 'utopian' package of political aims.
28 Freedom and Responsibility: the 'legitimist' package of political aims.
Pragmatic questions
29 Carry on differentializing?
30 Carry on psycho-testing?
Appendix: Factor Analysis. - 'Garbage in, garbage out'?

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