Quotations about

The main lines of battle about nature/nurture questions in general are set out in Quotes V; and questions about the psychometric measurement and the psychological bases of intelligence differences are covered in Quotes VIII and IX. Here, the concern is with nature and nurture (and with the 'nature via nurture', 'nature/nurture interaction', etc.) of the IQ-type differences found in children and adults. Classical studies of twins and adoptees are considered, as are modern data and modern interpretations; and it is also asked whether relatively novel environmental inputs to IQ-type intelligence levels may be occurring from distinctively late-twentieth-century improvements in pre-schooling ('Head Start' programmes), ante-natal care and diet.
The main general question is still that of the adequacy of the hereditarian vision, with whatever modifications and refinements: for few strong explanatory claims are advanced currently about intelligence from environmentalist quarters. A major adoption study by keen social-environmentalists in France (M.Schiff & R.C.Lewontin, 1986, Intelligence, Education and Class: the Irrelevance of I.Q-Genetic Studies) found no more effect of 'environment' than Arthur Jensen and Hans Eysenck had long predicted (see Brand, 1987, Nature 325); and an equally impressive study of separated twins recently came to largely (though not wholly) hereditarian conclusions (Bouchard et al., 1990, Science).
Many psychologists would support Leon Kamin (e.g. 1974, The Science and Politics of IQ; Rose, Kamin & Lewontin, 1984, Not in Our Genes, Penguin) in wishing to query what studies of twins and adoptees (and lately half-siblings - Teasdale & Owen, 1984, Nature 309) can really prove. This is because children, as they grow, increasingly select and create their very own environments (of friends, books, TV programmes, etc.- Plomin & Daniels, 1987, Behavioral & Brain Sciences 10). Thus it can seem as if nature and nurture 'cannot be separated-a welcome possibility to those who rather fear the power of 'nature' that might otherwise have to be admitted. Yet such complexities rejoice the hearts of hereditarians equally. The occurrence of such genetic-environmental covariation certainly does not culminate logically in a claim that the heritability of intelligence is zero-and Leon Kamin has wisely never made that claim. Rather, Kamin's support has been as much for 'agnosticism' as for his personally preferred class-based environmental explanations.
However, even agnosticism became a much harder position to maintain in the 1990's as psychogenetics had revived in the USA, Australia and Scandinavia, and as older (and sometimes dubious) studies could be set aside. If they are consistent in their antipathy to genetic inheritance, opponents of a high heritability estimate for IQ today must frankly doubt even the heritability of human height and weight differences-an unenviable position of self-declared ignorance after a century of genetic science. {The Edinburgh University geneticist, Professor Geoffrey Beale, used to attempt this feat; and his students Oliver Gillie and Professor Steve Jones (1991 BBC Reith Lectures) sometimes appear to continue this tradition.}
No matter how individual differences in g arose amongst children and adults in the past, it could still be that, today, we need to recognize other, relatively novel influences in IQ and IQ-type intelligence. One such type of influence may have been uncovered in the 'Head Start' programmes that were so popular in the USA in the 1970's, and in similar efforts in the 1980's by Reuven Feuerstein. Another influence, according to the New Zealand political scientist, Professor James Flynn, may involve some more naturally-occurring cultural, obstetric paediatric or dietary change that Flynn takes to have raised IQ levels "massively" in the West over the last two generations. {Flynn thus scorns those psychometrician-psychologists who feared that 'national intelligence' levels were actually declining. However, complicating matters, Flynn himself believes IQ tests measure not intelligence but merely "problem solving ability", "a correlate with weak causal links to intelligence"....} Such possible generational changes are therefore considered in the Quotes.
{Another possibility that IQ tests may pick up rather special-and artefactual- variance. This may happen especially when they are used to compare (e.g. across cultures) testees who approach tests with very different strategies (e.g. with very different speed / accuracy trade-off functions, or with different levels of confidence). Questions of the fairness of tests to particular groups of testees are considered in Quotes XXIV} Pointing to the future, perhaps, the work of Fagan and Bornstein has loosened the Piagetian shackles on developmental psychology by studying apparently simple processes of adaptation-to-novelty in infancy: this work is novel in showing that the intellectual differences of childhood and adulthood may already be detectably 'in place' in neonates-before many putatively environmental influences have had time to affect intelligence and yield individual differences.

{See Quotes V for nature/nurture issues in general-e.g. methodological problems.}


For more coverage of nature/nurture questions
about individual differences in intelligence, see:
BRAND, C.R. (1996). The g Factor.
Chichester : Wiley DePublisher.
[The book was first issued, in March, but then withdrawn by the 'publisher' because it was deemed to have infringed modern canons of
'political correctness.']

For a Summary of the book, Newsletters concerning the
de-publication affair, and others' comments
and reviews, see the Internet URL sites:

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:



(i) History of the nature/nurture debate about IQ 4

(ii) What about Sir Cyril Burt? 6

(iii) Modern hereditarian claims 12

(iv) Modern environmentalist claims 16

(v) Interactionist and transactionist claims 19

(vi) What about Head Start programmes? 22

(vii) What about intergenerational IQ-type changes? 30


(i) History of the nature/nurture debate about mental ability.

"Once feeble-minded, always feeble-minded-only in a less degree."
A.C.ROGERS (President of the Association of Officers of American
Institutions for Idiotic and Feeble-minded Persons), 1891.

"W.H.Cooley (1897, Annals Amer. Acad. Pol. & Soc. Science Rev. 9) questioned Galton's conclusion that genius alone is sufficient to cause a person to rise to fame, but he appeared not to reject Galton's notion that genius was hereditary. The issue first became prominent in the 1920's, with Walter Lippmann's (1922, New Republic 32) critique of intelligence testing, and again in the late 1930's with the claim of a group of University of Iowa psychologists (Skeels & Dye, 1939, Proc. Amer. Assoc. Mental Deficiency 44) that intelligence could be increased by special training and environmental adjustments."
J.B.CARROLL, 1993, Human Cognitive Abilities.
Cambridge University Press.

"....research carried out by Mr Hugh Gordon puts to a prolonged trial the assertion made by many test enthusiasts....that almost total absence of schooling leaves the Binet IQ uninfluenced. To test this in a systematic way Mr Gordon turned to two special classes in England, gypsies and canal boatmen, whose children get very much less schooling than the ordinary child. His general plan was to see whether, under such neglect, the IQ sinks as the child gets older, and his evidence points to this being the case."
Godfrey H. THOMSON, 1924, Instinct, Intelligence and Character.
London : George Allen & Unwin.

"[A] milestone in twin studies was reached in 1924. In a study reported in Psychological Monographs, Curtis Merriman (1924) was the first to employ standardized individual and group IQ tests to test the intellectual similarities of twins. The results of his investigation finally convinced psychologists that there are two types of twins, fraternal (two eggs) and identical (one egg)."
R.Travis OSBORNE, 1980, Twins: Black and White. Foundation
for Human Understanding: Alexandria, VA ; Athens, GA.

"The native intelligence hypothesis is dead."
C.C.BRIGHAM, 1930.

"....the child's intellectual qualities, his intelligence, is acquired through learning."
A.W.STAATS, 1971, Child Learning, Intelligence and Personality.
New York : Harper & Row.

"Geneticism is a word that has been coined to describe the enthusiastic misapplication of not fully understood genetic principles in situations to which they do not apply. IQ psychologists are among its most advanced practitioners...."
P.B. & J.S. MEDAWAR, 1977.

"Intelligence tests may help predict children's school performance, but they say nothing about any fixed 'biological potential' of the individual."
UK National Union of Teachers, 1978, Race, Intelligence and
Education: A Teacher's Guide to the Facts and Issues

"We do not have 'genes for intelligence'."
D.W.PYLE, 1979.

"It is my conviction that the isolation of the mental abilities will turn out to be essentially a problem in genetics."
L.L.THURSTONE, 1934, Psychological Review 41.

"There can be no doubt that intelligence, however it may be measured, is to some degree inherited, and that most of the genetically determined variation is multifactorial, i.e. due to many genes, each with small effects."
D.S.FALCONER (Edinburgh University Professor of Genetics), 1966.

"It is not true that everyone can reach the same academic standards if provided with adequate opportunities, and the heritability of IQ is a partial measure of that untruth."
J.M.THODAY, 1973, Nature.

"[L.Kamin's The Science and Politics of IQ] lacks balanced judgement and presents a travesty of the empirical evidence in the field. By exaggerating the importance of what are, in reality, idiosyncratic details rather than typical features, he totally avoids the necessity to consider the data as a whole. The cumulative figure is overwhelmingly in favour of a substantial heritability of IQ"
D.W.FULKER, 1975, American Journal of Psychology 88.

"....the 'environmental' influences of family background, economic stress and ethnic origin on IQ's are being grossly overestimated by the psychosocially minded educator."
R.KOHEN-RAZ, 1977, Psychological Aspects of Cognitive Growth.
New York : Academic Press.

"A mere decade from now....even questions of whether intelligence....is inherited....will become respectable for the first time since the nineteenth century."
Editorial in Nature, 14 iv 1983.

(ii)What about Sir Cyril Burt?

"[Burt] was undoubtedly the first psychologist to understand thoroughly, and to use, the important contributions of Fisher, Haldane and Mather in biometrical genetics.... In the theoretical aspects of the applications of quantitative genetics to psychological data Burt was outstandingly ahead of all others of his time."
A.R.JENSEN, 1974, Behavior Genetics 4.

"[To cope with Menière's attacks I] found it a good rule to keep absolutely still where one is, and particularly to avoid moving the head about from the very onset. (One is tempted to rush off to a bedroom and collect basins and towels around one {to cope with vomiting}.) Then when the world begins to go round it seems pretty effective steadily to fixate a given spot with the eyes. This has to be kept up with little intermittence for three-quarters of an hour or more, and so ultimately gets very tiring.... [The attacks of giddiness are] of course very violent. The tiniest movement of the head is apt to make one feel as though the bed had rapidly shifted its position and angle by many yards and by many degrees. Also the world will spin round with amazing rapidity when the nystagmus begins - that is if one lets the nystagmus have its way."
C.L.BURT, 1942, letter to his sister, Dr Marion Burt, 22 ii.

"[In 1943] Burt expressed doubts on the desirability of 11+ as the age of transition [to secondary schooling]. 'The grounds for allocating children to schools of different types at the early age of 11 are administrative rather than psychological', he now maintained. He objected also to the delineation of three types of child based on their possession of qualitatively different specific aptitudes (verbal, mechanical and practical) rather than on 'all-round innate capacity'.... And he perspicaciously asked whether 'once the children have been sent to some special types of school at the age of 11 there is really much likelihood of any large re-sorting at a later age."
L.S.HEARNSHAW, 1979, Cyril Burt: Psychologist.
London : Hodder & Stoughton.

"I would like it to be emphasised that throughout his whole life Cyril was handicapped by poor health.... he was understandably secretive....lest he should be judged 'neurotic'.... his intimate friends were men with permanent physical or physiological drawbacks.... ....I think his semi-circular canals were not innately very efficient.... [he had] more than normal difficulty in learning to cycle and to dance; great difficulty, according to Mother, to get him to jump even from a couple of steps; also virtual horror of the school gymnasium, as you can see in his letters from Christ's Hospital, pathetically begging his father to get him excused from it."
Dr Marion Burt, c. 1975, to L.S.HEARNSHAW, and given in Cyril Burt: Psychologist. London : Hodder & Stoughton.

"There was really no point in preserving [Burt's documents]: only Professor Burt himself could have re-assembled and reworked them, should there ever have been cause to do so. Whether they dealt specifically with his twin studies, or some other project, I do not know."
Professor Liam HUDSON {the Professor of Education (at Edinburgh University at the time) who, on Burt's death (1971), advised Burt's housekeeper to get rid of the piles of documents kept in his attic}. Quoted by Stephen BATES, 1992, 'Intelligence Quotient 2',
Weekend Guardian, 18/19 vii.

"Lionel Penrose is credited with remarking of a lecture given by Burt: "I greatly admire the way the old boy says it-but I don't believe a word of what he says.""
W.H.JAMES, 1995, 'Fraud and hoaxes in science.' Nature 377.

"[In the Sunday Times of 24 x 1976], four main charges were levelled against Burt by Gillie:
first, Burt often guessed parental IQ's....;
secondly, that [two female collaborators never existed];
thirdly, that the concordant correlations noted by Kamin could only
have been arrived at by working backwards....;
fourth, that Burt fabricated data to fit the predictions of his
favoured genetic theories....
....[From Burt's post-1953 diaries, over the period when he claimed to have been gathering fresh data on the intelligence monozygotic twins reared in uncorrelated environments] we can be sure that Burt himself did not collect any data on twins, or any other topic, during these years, and that he was never visited either by Miss Howard, or by Miss Conway [claimed as co-researchers], or by any other assistant actively working for him.... We are forced....to the conclusion that the accounts given in Burt's published papers were false, and that a measure of deception was certainly involved.
[However] the 1955 paper and the 1966 paper were written in pique and in answer to his critics.... They were not, in the proper sense, research reports, written calmly and painstakingly.... We must not forget, too, that Burt was all the time heavily involved in other activities - in 1964, for example, he read and reported on twenty-one manuscripts for Allen and Unwin, wrote other articles, acted as examiner, reviewed books, sometimes at length, and [at age eighty-one, suffering è disease and deafness] wrote hundreds of letters. In such circumstances careless mistakes are likely to occur.... Burt himself was well aware of [his] tendency to inaccuracy.... [In 1963] he said 'My mind seems to be ageing.... What I write has to be checked and re-written many times before it is fit for the printer. Most of the mistakes are quite childish.'
[Carelessness] was not, however, the only ingredient. There was also deception.... ....[By c. 1955, Burt's] whole world was insecure. His home had broken up; his research data had perished; his health was precarious; his old department had defected; he had been robbed of his journal; new modes of thinking and younger rivals were ousting him from the centre of the stage; the doctrines he believed in were being rejected. The changes in his personality from the late 1930's onwards were responses to these threats.... He attempted to fight his battles single-handed, and in doing so became distinctly paranoid.... ....[Yet] the combination of a high-powered grasp of scientific methodology with humanistic insight makes Burt's theoretical psychology [with its dualism, evolutionism, holism, probabilism] important, and indeed almost unique. It was well in advance of its times, and also, it must be admitted, far beyond Burt's capacity to realise in practice.... ....Nevertheless the future may well vindicate the central core of Burt's insights - his stress on individuality, and the importance of some genetic contribution to it; his faith in quantification; his hierarchical reconciliation of university and diversity; and his blending of humanism and methodology.... .... In spite of the tragic flaws in his character Burt may yet be accorded a place in history as one of psychology's imaginative pioneers."
L.S.HEARNSHAW, 1979, Cyril Burt: Psychologist.
London : Hodder & Stoughton.

"Hearnshaw has mistaken the direction of causality when he suggests that [Menière's] disease was a cause of Burt's moral aberrations."
O.GILLIE, 1980.

"We conclude....that Burt's contribution to typographic practice was marred by the same defects that one can find in his other work."
J.HARTLEY & D.ROOUM, 1983, British Journal of Psychology.

"....I could not take [Burt] seriously. He was vain, and status-conscious to an absurd degree.... He wrote superbly on occasion, but often spoiled the effect by putting in long footnotes, the only purpose of which was to show off his erudition.... Burt was a great scientist, but a very odd human being. I was lucky in having an outstanding psychometrician as a teacher but unlucky in having to deal with a psychopath."
Hans EYSENCK, 1994, Times Higher Educational Supplement, 10 x.

"[Burt] must either simply have fabricated the data [on secular trends in IQ], or have relied on different tests at different times, which, in spite of his explicit claims to the contrary, he had never standardized against each other."
N.J.MACKINTOSH, 1995, 'Does it matter? The scientific and political impact of Burt's work.' In N.J.Mackintosh, Cyril Burt: Fraud or Framed? Oxford University Press.

"Mackintosh [in N.J.Mackintosh (ed.), Cyril Burt: Fraud or Framed, O.U.P.] ....justifiably concludes that Burt is at least guilty of deception. [However,] Eysenck states that "at bottom, [Burt] preferred theory and statistical analysis to experimental rigour and hypothesis testing along deductive lines." I more or less agree.... ....I believe it is misleading to hold [Burt] up as the icon of academic fraud."
R.AUDLEY, 1995, 'A true pro and his cons.'
Times Higher Educational Supplement, 20 x.

"The fact that the researches of others and later studies come to broadly similar conclusions [to Burt's] is only relevant insofar that Burt may indeed have 'arranged' his later work to join this consensus."
Halla BELOFF (former President of the British Psychological Society), 1996, Behaviour Research & Therapy.

"My critics seem to be suggesting that Burt suffered from innate wickedness - a strange contention indeed from the opponents of heredity!
Bulletin of British Psychol. Society 74.

"I conclude that Burt's exposure makes very little difference to our knowledge of IQ and its heritability...."
J.M.THODAY, 1981, Nature 291.
(Reviewing Halla Beloff (ed.), A Balance Sheet on Burt.)

"Having savagely attacked Burt for "elitism", for opposing equality of opportunity, for advocating a kind of selection to secondary education which was on a par with Nazi policies on race [Oliver Gillie, the scientific journalist] who made the first public charge of fraud against Burt (in The Sunday Times, 24 x 1976) himself sent his children to private schools."
Prof. Ronald FLETCHER, 1987, Social Policy & Administration 21.

"Burt's work was more detached than that of Kamin, more self-critical than that of Eysenck, more firmly based in experience than that of the Clarkes, more accurate than that of Hearnshaw, and more knowledgeable than that of all of them combined. But all was to no avail once he was dead. Then he could be attacked with impunity."
R.B.JOYNSON, 1989, The Burt Affair. London : Routledge.

"On the basis of a detailed analysis, R.Fletcher (1991, Science, Ideology and the Media: the Cyril Burt Scandal, Transaction Publishers) finds the only suspicious invariant correlation [in Burt's twin data] to be the repetition in 1966 of [the correlation of] 0.771 first found in 1955. But in 1966, Burt was 82 years old, with declining powers of concentration, doing all his calculations by hand, and writing in haste to reply to other articles. Because the increasing sample sizes were cumulative additions, it is more plausible to suppose that Burt added [extra] cases to his collection without bothering to calculate new correlations than it is to conjecture that the long-time editor of the British Journal of Statistical Psychology would stupidly fabricate improbably invariant correlations in an effort to deceive other experts. That L.S.Hearnshaw (1979, Cyril Burt) was forced to concoct a speculative psychopathology {Burt's supposed gamin complex} to make such a fraud charge credible shows the weakness of the charge, which appears even more bizarre as Hearnshaw relied mainly on Burt's "mixed ancestry" - part Saxon and part Celtic."
Lee LOEVINGER, 1991, 'Raking over the coals'. Nature 352, 11 vii.

"Perhaps the biggest difficulty for any critic of Burt is that Burt was spectacularly correct on so many straightforward yet often-contested points. (Could he really have managed without data?)"
C.R.BRAND, 1995, Nature, x.

"The Broad & Wade book (1982, Betrayers of the Truth, OUP) names many famous scientists as having deviated significantly from the paths of righteousness, including Ptolemy, Galileo, Newton, Dalton, Mendel and Millikan (the American Nobel Laureate who was the first to measure the electric charge on the electron). ....Modern times also have their share of fraud, as Broad and Wade testify, but their account is somewhat selective. ....Broad and Wade take it for granted that Burt was guilty, but the evidence is equivocal [and] numerous undoubted cases of fraud by environmentalists are ignored."
H.J.EYSENCK, 1995, Genius: the Natural History of Creativity. Cambridge University Press.


"Early in 1992, a number of scholars in Great Britain made an effort to get the British Psychological Society, which had formally condemned Burt in 1979, to reverese that judgment. ...The BPS said:"....We have decided that we ought not to be taking a corporate position at all." ....But, of course, the learned body had taken a "corporate position", judging Burt guilty, in 1979."
Daniel SELIGMAN, 1992, A Question of Intelligence:
the IQ Debate in America.
New York : Carol (Birch Lane).

"[He is] most anxious to make contact with those he suspects to be most critical. The deepest critics prompt lengthy rebuttals....Here is a man of charm, wit and stunning intellect often turning to deception, secrecy and bullying as his preferred weapons.... He became famed for his mastery of the press.... 'Power', he observed. 'is the great aphrodisiac', though [one of his dates observed] that power appeared to be the climax as well.... As a solo performer he was soon isolated when things went wrong."
Lawrence FREEDMAN, 1992, The Spectator, 21 xi.
Reviewing a biography of Henry Kissinger.

"One perennial issue that commands attention is whether Mendel's data were falsified to improve the goodness of fit. Suffice it to say here that, in the majority of experiments, there is no indication of adjustment. At most there is a shortage of extreme deviates suggesting that a few experiments at the tails might have been disregarded or repeated."
D.L.HARTL, 1995, Trends in Genetics 11, p.524.

(iii) Modern hereditarian claims

"....an autosomal-recessive allele, M1, in the homozygous state is the prerequisite to the ability to perform high-level mathematical, technical and other work, and to having an IQ higher than 130."
V.WEISS, 1979, to International Congress of Psychology, Leipzig.

"The laws of genetics [concerning IQ] work the same way in the D.D.R. {Communist East Germany} and the USSR as in the West, and are now admitted to do so."
H.J.EYSENCK, 1983, New Scientist. (Reviewing the work of the East
German psychogeneticist, Volkmar Weiss {see above}.)

"That the data {in a review of similarities between 113,942 pairs of relatives} support the inference of partial genetic determination of IQ is indisputable; that they are informative about the precise strength of this effect is dubious."
T.J.BOUCHARD Jr. & M.McGUE, 1981, Science 212.

"[In a study of 324 hereditary monarchs] intelligence does seem to be transferred across generations according to the laws of genetics. For example, a son's intellectual inheritance from his father is twice as great as that from his grandfather.... the grandfather makes no contribution to the son's intelligence once the father's contribution is controlled. Finally, the inheritance of intelligence is the same no matter what the sex of the monarch may be: a queen owes just as much of her intellect to her father as a king to his. Eminence is inherited in an entirely different way...."
D.K.SIMONTON, 1984, Genius, Creativity and Leadership.
Cambridge, Mass. : Harvard University Press.

"In a sample of 122 undergraduate students, tongue-curling ability, light eye colour and inability to taste phenylthiocarbamide (PTC) were related to high intelligence.... The small size (about .20) of the significant correlations between genetic markers and....intelligence....does not detract from their importance. Indeed, if the markers are genetically simple and the psychological variables are genetically complex, small correlations would be expected." T.A.GENTRY et al., 1985, Personality & Individual Differences 6.

"For the majority of children reared in a wide range of humane environments, genetic influences, inferred from twin and adoption studies, show up as more important than do environmental effects in promoting differences [in intelligence]."
Ann M. CLARKE & A.D.B.CLARKE, 1986,
Journal of Child Psychology and Psychiatry 27.

"{Not all abilities are heritable.} The more g-loaded the test, the higher is the kinship correlation shown by the test.... the degree of heritability of the various tests is directly related to the tests' g loadings, with a correlation of about .70...."
A.R.JENSEN, 1986, speaking in Blackwood, Virginia.

"Human intelligence, as measured by traditional tests and by more contemporary information-processing tasks, is about 50% heritable; the remaining variance is largely due to individual experience, not common to siblings in the same family or to parents and children."
Sandra SCARR, 1986, in R.J.Sternberg & D.K.Detterman,
What is Intelligence? Hillsdale, NJ : Ablex.

"Since 1956, when human chromosomes were first clearly observed and counted, the number of chromosomal abnormalities found to produce mental retardation has increased at a phenomenal rate. In 1958, the extra chromosome in Down's syndrome was discovered. In 1969, the fragile X syndrome was first described and....it soon became evident that this syndrome rivals Down's syndrome as a genetic cause of mental retardation." H.H.SPITZ, 1986, The Raising of Intelligence.
Hillsdale, NJ : Lawrence Erlbaum Associates.

"Fagan has shown in a whole series of papers that neonates can discriminate between novel and not-so-novel visual stimuli; and this ability, indexed by length of regard and thumb-sucking behaviour, is quite highly correlated [r = .72 after correction for attenuation] with IQ as measured several years later."
H.J.EYSENCK, 1986, Personality and Individual Differences 7.

"The older data are compatible with a heritability [for IQ] of .70 or higher, whereas the newer data suggest a heritability closer to .50.... It has been suggested that the lower heritability of IQ implied by the newer studies is due to reduced variance (D.Caruso, 1983, Behaviour Genetics 13).....
In a study of Indian schoolboys, an inbred group of eighty-six boys whose parents were first cousins had significantly lower IQ scores than classmates whose parents are genetically unrelated (N.Agrawal et al., 1984, Behaviour Genetics 14).... ....A decade and a half ago, Jensen clearly and forcefully asserted that IQ scores are substantially influenced by genetic differences among individuals. No telling criticism has been made of this assertion, and newer data consistently support it. No other finding in the behavioural sciences has been researched so extensively, subjected to so much scrutiny, and verified so consistently."
R.PLOMIN, 1987, in S. & Celia Modgil, Arthur Jensen: Consensus
and Controversy
. Brighton : Falmer.

"[There is possible] bias in selection of twins-especially the DZs-who get to participate in [psychogenetic] studies.... Parents are thought to be much less co-operative when they have reason to believe that one of the fraternal twins will test significantly higher than the other (Lykken, 1981, Psychophysiology 19)."
Daniel SELIGMAN, 1992, A Question of Intelligence:
the IQ Debate in America.
New York : Carol (Birch Lane).

"The degree of relationship between myopia and mental ability in the general school population, as estimated in three large studies, when expressed as a coefficient of correlation, is about .20 to .25, which is equivalent to an IQ difference of about 6 to 8 points between myopes and nonmyopes. ....If reading were the cause of the association between myopia and intellectual ability, one would expect a stronger correlation of myopia with education than with intelligence. ....Cohn et al. (1988, Hum.Genetics 80) conclude that [genetic] pleiotropy is the most plausible explanation."
A.R.JENSEN & S.N.SINHA, 1994, 'Physical correlates of human intelligence.' In P.A.Vernon, Biological Approaches to the Study of Human Intelligence. Norwood, NJ : Ablex.

"Consider [a] criticism that has repeatedly surfaced regarding the similarity of MZA twins in IQ. It is asserted that "people treat children as more or less bright and capable according to whether they look bright or not, and this treatment affects the child's actual performance (the Pygmalion effect." Since MZA twins look so much alike, this effect is purported to explain why they have similar adult IQs. If we unpack the assumptions of this claim, we find that (a) there must be high inter-rater agreement in judging the brightness of young children from their appearance (otherwise the two sets of adoptive parents would not treat both twins in the same way); (b) adoptive parents will persist in evaluating their adoptive child's brightness on the basis of his or her looks, in spite of growing acquaintance with his/her behavior; (c) identical twins reared apart are sufficiently similar in appearance so that they are treated in a highly similar manner; and (d) differential treatment based on such assessments can move the IQ of individual twins up or down over the entire normal range of IQ variation. ....Burks and Tolman (1932) long ago showed that physical resemblance in sibling pairs was unrelated to resemblance in IQ."
T.J.BOUCHARD, 1994, 'The genetic architecture of human intelligence.' In P.A.Vernon, Biological Approaches to the Study of Human Intelligence, pp.33-93. Norwood, NJ : Ablex.

"Eysenck, Hans (b. 1916): Controversial psychologist. Member of the Vienna Circle. Using a vigorously scientific approach, he has entered the 'nature-versus-nurture' debate to prove that since white, Tory, cigarette-smoking males are demonstrably superior to black, politically motivated, non-smoking females, it follows that IQ is genetically transmitted. Andrew Alexander writes 'Plain obvious, I'd have thought'."
'Henry ROOT', 1981, Henry Root's Book of Knowledge.
London : Sphere Paperbacks.

"My own evaluation....of the allegedly scientific analyses of the IQ data is more caustic. Suffice it to say that it seems that there has been a great deal of action with numbers but not much progress-or sometimes not even much common sense."
S.FARBER, 1981, Identical Twins Reared Apart. New York : Basic.

"....many of the key "facts" asserted by Jensen, Eysenck and other hereditarian theorists are simply not true.... Professor Eysenck has told his readers, glowingly, of a "revolution in analysis" brought about by geneticists- one that psychologists might understand, but presumably beyond the grasp of laymen. We have been forced to note, however, that there are no clear and reliable data to which these revolutionary models can be applied."
L.KAMIN, 1981, in H.J.Eysenck & L.J.Kamin, Intelligence: The
Battle for the Mind
. London : Pan.

"We consider that anybody approaching [the field of mental testing] for the first time and expecting to find a gradually accumulating body of knowledge about the role of heredity in human intellectual variation would be sadly disappointed. What is in fact to be found is a very slender quantity of empirical research distributed over a period of about fifty years, fraudulent in one important case, methodologically weak in almost all cases, and open to a wide range of possible interpretations concerning the role of heredity."
B.EVANS & B.WAITES, 1981, IQ and Mental Testing.
London : Macmillan.

"....since we can assume that intelligence....has resulted from exceptionally intense selection-one indication is the extraordinarily rapid rate of hominid brain expansion in the Pleistocene-we would expect a great reduction in the genetic variability and fixation [of intelligence] as a species-specific trait."
International Journal of Psychology 19.

"In contradiction to the studies of Eysenck and Jensen, it has been found that children reared by the same mother are found to resemble her in IQ to the same degree, whether or not they share her genes (see S.Rose et al., 1984, Not in Our Genes, Penguin)."
Peter WHEALE and Ruth McNALLY, 1988, Genetic Engineering:
Catastrophe or Utopia?
Hertfordshire : Harvester/Wheatsheaf.

(iv) Modern environmentalist claims

"What children can do with others today, they can do alone tomorrow."

"Intelligent behaviour is operant behaviour; therefore, it is learned and can be taught."
W.C.BECKER, S.ENGELMANN et al., 1982, in P.Kardy & J.J.Steffeln,
Improving Children's Competence. Lexington, MA : Lexington Books.

"A striking demonstration [of the effect of schooling on intelligence] appeared when the schools in one Virginia county closed for several years in the 1960's to avoid integration, leaving most Black children with no formal education. Compared to controls, the intelligence-test scores of these children dropped by about 0.4 standard deviations (6 points) per missed year of school (Green et al., 1964).
Extract from Intelligence: Knowns and Unknowns-Report of a Task Force established by the Board of the Scientific Affairs of the American Psychological Association, Chairman U. Neisser, 1995. Washington, DC : APA Science Directorate.

"We know of no specific environmental influences nor combination of them that account for as much as 10 per cent of the variance in IQ"
Intelligence 4.

"In his reply to Jensen's Harvard Educational Review article (1969), Arthur Stinchcombe (1969, HER 39) claimed that environments accumulate in much the same way as interest does when compounded. A modest initial difference of 2% in environment results after 20 years in a 150% difference. Johnson (1963, Child Dev. 34) found no evidence of early environmental influence on IQ.... If length of time spent in the same environment has a significant effect on intelligence test performance, then younger individuals....should resemble their twins less closely than older identical twins....We would....expect the correlation between age and IQ difference for both MZ and DZ twins to be negative if environmental influences are cumulative.
Four hundred and twenty-seven pairs of twins [age 12-20, 29% black] , living together at home with their parents or guardians, were tested in Kentucky and Georgia with a large battery of mental tests. ....the trend of differences [within twin pairs] is unrelated to age of twins. ....since the intraclass r's....show no systematic change with age, the cumulative environmental hypothesis which would predict a monotonic increase in r's with age must be rejected."
R.Travis OSBORNE, 1980, Twins: Black and White. Foundation
for Human Understanding: Alexandria, VA ; Athens, GA.

"....one never knows what is being stated positively by environmentalists."
H.J.EYSENCK, 1981, in H.J.Eysenck & L.J.Kamin,
Intelligence: The Battle for the Mind. London : Pan.

"Kamin's claim that the heritability of intelligence cannot be shown to be greater than zero is unsupportable."
J.B.CARROLL, 1982, in R.J.Sternberg,
A Handbook for Human Intelligence. Cambridge University Press.

"Kamin has carefully selected his facts in the service of a social cause.... Nowhere in Kamin's writing on the topic of IQ do we find a reasonable explanation of how environments and genes determine the distribution of IQ in a population, or the correlations between relatives.... Kamin's analysis is truly a pseudo-analysis. He does not confront the data as a whole because he cannot."
T.J.BOUCHARD Jr., 1982, American Journal of Psychology 95.

"Anti-hereditarians have been more prone to taking pot-shots at the other side than to developing a coherent programme of their own."
F.SAMELSON, 1982, Contemporary Psychology. (Reviewing IQ and
Mental Testing: An Unnatural Science and its Social History

"{In a study of retarded children growing up}, pupils who had experienced the most serious problems as children were less retarded at adult age than persons who had experienced few or no problems. The results may give support to Clarke and Clarke's hypothesis that the effects of an early unstimulating environment are not necessarily irreversible."
D.SVENDSEN, 1982, Journal of Child Psychology & Psychiatry 23.

"There seems....to be a threshold above which humane environments of a wide range do not exercise much differential effect on measured intelligence."
Ann M. CLARKE, 1984, Educational Psychology.

"....for neither Education or IQ is there substantial cultural transmission." M.C.NEALE & D.W.FULKER, 1984, Bulletin of the British
Psychological Society
, ii (A30).

"The post-1968 New Left in Britain and the United States has shown a tendency to see human nature as almost infinitely plastic, to deny biology and acknowledge only social construction. The helplessness of childhood, the existential pain of madness, the frailties of old age were all transmuted to mere 'labels' reflecting disparities in power. But this denial of biology is so contrary to actual lived experience that it has rendered people the more ideologically vulnerable to the "common-sense" appeal of re-emerging biological determinism."
S.ROSE, L.J.KAMIN & R.C.LEWONTIN, 1984, Not in Our Genes.
Harmondsworth : Penguin.

"Genetically unrelated pairs of children growing up in the same home, when tested at an average age of seven or eight, correlated r = .26 for Wechsler IQ Ten years later they correlate near zero. Thus there is an age decline in the importance of shared family environmental factors on IQ resemblance."
Journal of Child Psychology & Psychiatry 27.

"Arthur Jensen himself has long supposed that each standard deviation of parental socio-economic status (S.E.S) is worth (as a causal influence) some 3.35 IQ points to a child. So the adoptees of the present study [adopted into homes that were two-and-a-half standard deviations high in SES-M.Schiff & R.C.Lewontin, Education and Class: the Irrelevance of IQ Genetic Studies], on a mainstream hereditarian account, should have had a boost of 2.5 x 3.35 = 8.4 IQ points, plus an extra IQ advantage from adoption alone. Thus it is quite unclear what the authors feel they are battling against."
{Schiff & Lewontin's adoptees in fact showed an 8-IQ-point advantage over their non-adopted siblings on culture-reduced IQ testing; yet Schiff & Lewontin did not admit that their results were well in line with Jensen's theorizing.}
C.R.BRAND, 1987, Nature 325, 26 ii.

"The vast majority of environmental factors thought to be important by psychologists and others do influence IQ Their influence, however, is invariably much less than expected."
T.J.BOUCHARD Jr., 1987, in S. & Celia Modgil, Arthur Jensen:
Consensus & Controversy
. Brighton : Falmer.

"....the bulk of the variance [on Raven's Progressive Matrices] is between children from similar ethnic and socio-economic backgrounds. Indeed, as Maxwell (1969, Sixteen Years On) and Jencks et al.
(1973, Intelligence) have shown, two-thirds of the variance in intelligence test scores is between children from the same families."
J.RAVEN, 1989, Journal of Educational Measurement 26.

"The massive US Collaborative Perinatal Project followed pregnant mothers and their 26,000 eventual offspring (Broman et al., 1975, PreSchool IQ). The data analysis on the children's IQ at 4 years of age involved 169 variables, among which were many of prenatal, perinatal and neonatal origin. The results suggested collectively that only 3 to 4 per cent of the IQ variations could be accounted for by these factors, and some of the pregnancy complications might be signs of an already compromised fetus vulnerable to otherwise unexceptional stress."
L.WILLERMAN, 1990, Cahiers de Psychologie Cognitive 10.

"It is not that we have found no evidence of environmental influence [on identical twins reared in different environments]; in individual cases environmental factors have been highly significant [one twin pair had a 29-IQ-point difference]. Rather, we find little support for the types of environmental influences on which psychologists have traditionally focussed."
T.J.BOUCHARD et al., 1990, 'Sources of human psychological
differences: the Minnesota study of twins reared apart'.
Science 250, 12 x.

"The extent to which Kamin (1974, The Science and Politics of IQ) went to deride the genetic hypothesis knew no bounds. For instance, twenty-seven of the forty pairs of twins studied by Shields (1962, Monozygotic Twins) were raised by relatives. Kamin calculates the inter-twin correlations for those reared with relatives was .83, whereas for the thirteen pairs with unrelated foster parents the correlation was .51. The latter correlation is similar to that observed for DZ twins reared together. Fulker (1975, Amer.J.Psychol.88) pointed out that first cousins are likewise reared by relatives and often have childhood contacts, yet their intercorrelation is .26, not .83. In addition, the group with the more dissimilar environments, which gave the correlation of .51, happened to include three highly bizarre and abnormal pairs, and omitting these brings the correlations for the ten remaining pairs up to the same level as for the twenty-seven reared with relatives!"
C.G.N.MASCIE-TAYLOR, 1993, In M.Keynes, Sir Francis Galton, FRS.
London : Macmillan (in association with the Galton Institute).

"What emerges most clearly [from D.H.Rost's (1992) comparison of gifted {high-g} children with SES-matched non-gifted children] is the absence of any obvious environmental factors to explain the observed differences in "giftedness"."
H.J.EYSENCK, 1993, Personality & Individual Differences 15.

"According to Taylor (1980) (and many others) 'similarity in....social environment is a central reason why MZA twins....reveal similar IQ scores'.... Taylor's classification yields a weighted average correlation of .85 for twins reared in strongly similar environments and .46 for those reared in minimally similar environments.... The findings, however, totally fail to replicate when the alternate tests used in [the classic MZA studies] are employed in the analysis. The finding even slightly reverses itself. Twins reared in minimally similar environments show a correlation of .70, hardly different from the overall correlation of .72 for the entire sample. Clearly, Taylor's thesis is totally refuted."
T.J.BOUCHARD, 1994, 'The genetic architecture of human intelligence.' In P.A.Vernon, Biological Approaches to the Study of Human Intelligence, pp.33-93. Norwood, NJ : Ablex.

"Severely deprived, neglectful or abusive environments must have negative effects on a great many aspects of development, including intelligence. Beyond that minimum, however, the role of family experience is now in serious dispute (Baumrind and Jackson and Scarr, 1993, Child Development 64).
Extract from Intelligence: Knowns and Unknowns-Report of a Task Force established by the Board of the Scientific Affairs of the American Psychological Association, Chairman U. Neisser, 1995. Washington, DC : American Psychological Association.

(v) Interactionist and transactionist claims

"What are 'low-IQ genes' in one environment are 'normal-IQ genes' in another."
National Union of Teachers, 1978.

"There is probably only one way in which genuinely independent genetic influences might be constrained into operating as joint contributors to one final phenotypic variable while having little phenotypic visibility of their own. Such constraint would exist if most of such genetic influences operated only upon (or at least in accordance with) the prior phenotypic products of other genes in the system; and such a genetic state of affairs would seem to provide a natural basis for 'growth'-whether of a tree, of a limb, or of intelligence itself."
C.R.BRAND, 1984, in C.J.Turner & H.B.Miles, The Biology of
. North Humberside : Nafferton Books.

"In Jencks' (1980) very persuasive terms, whether IQ tests have genetic or environmental origins, whatever is genetic in them operates largely via the environment (including the intra-uterine environment) rather than independently of it. The message is that heritability estimates tell us precisely nothing about the limits on human cognitive growth."
International Journal of Psychology 19.

"The problem is that heredity, environment and the interaction between heredity and environment all play some role in intelligence as it has traditionally been measured, but it is not at all clear what the relative extents of these roles are."
R.J.STERNBERG, 1987, 'Intelligence'.
In R.L.Gregory, Oxford Companion to the Mind.

"The process whereby the genotype reads out into the phenotype and creates individual environments that then feed back, causally, into the phenotype, may be called one of transaction. It is arguably an important process that has been neglected, or at least imprecisely formulated, while inchoate developmental psychologists have preferred to opt out of nature vs nurture arguments about human differences by appealing to obscure 'interaction effects' that are, in their work, forever unspecified. Transaction, by contrast, is a clear spelling-out of the basic hereditarian idea: that individuals move in their own ways, when given the opportunities, to select and create environments that are enriching and fulfilling-or, in some cases, otherwise."
Editorial, 1987, Biology and Society 4.

"....the results of the present study suggest that the heritability of IQ increases as a function of a child's age. Moreover, the relationship between ostensible environmental measures [of the quality of the home] and children's IQ's also increases. However, this change is not due to greater environmental influences - it is due to genetic mediation."
Intelligence 12.

"The major new idea suggested by [my] theory is that intelligence does not develop.... development could take place without the need for any change in the underlying mechanisms. Children may become "more intelligent" simply because they are around longer and have built up more knowledge that they can apply to solve problems."
M.ANDERSON, 1989, The Psychologist, iii.

"Arguably, g is to the psychology of personality what carbon is to chemistry: g accounts for more variance in important human behaviours than do all the other variables in anthropology, sociology and experimental psychology put together.... So long as g is high, we see conspicuous diversity, readily trapped in suitable questionnaires. As has been claimed for intelligence itself, this may involve more dimensions; but, certainly in some of our own data and that from the large Myers-Briggs normative sample, it seems to involve higher-IQ subjects showing more distinction amongst themselves.... Intelligence fuels and sustains personality until old age sets in...."
C.R.BRAND, V.EGAN & I.J.DEARY, 1994, 'Intelligence, personality
and society: constructivist versus essentialist possibilities.' In D.K.Detterman, Current Topics in Human Intelligence 4.
Norwood, NJ : Ablex.

"In types of work that involve special talents and particular highly developed skills, such as musical, literary and artistic performance, g usually acts as a threshold variable. That is, the probability of successful development of the special talent falls off precipitously for individuals who fall below some critical or threshold value."
A.R.JENSEN, 1994, 'Phlogiston, animal magnetism and intelligence.'
In D.K.Detterman, Current Topics in Human Intelligence 4: Theories of Intelligence. Norwood, NJ: Ablex.

(vi) What about Head Start programmes?

"If I had been by nature extremely quick of apprehension, or had possessed a very accurate and retentive memory, the trial {of his father's intensive-and apparently successful-educational programme for him in childhood} would not have been conclusive; but in all these, naturally, I am rather below than above par. What I could do, could assuredly be done by any boy or girl of average capacity and healthy physical constitution."
J.S.MILL, Autobiography.
London : Oxford University Press, 1971.

"There is room for a great experiment which could repay society more than any number of studies on so-called feeble-minded families.... Children of known defective groups, both parents being feeble-minded, might be removed very early in life from the environment created for them by their parents.... If placed under the best environmental circumstances, it would not take more than ten years to discover whether or not they were destined to be feeble-minded, and whether or not there was an upward rise in their intelligence as contrasted with that of their parents."
A.MYERSON, 1930, Journal of Psycho-Asthenics 35.

"A change from marked mental retardation to normal intelligence in children of pre-school age is possible in the absence of organic disease or clinical deficiency by providing a more adequate psychological prescription."
H.A.SKEELS, 1942, American Journal of Mental Deficiency 46.

"Compensatory education has been tried and apparently it has failed."
A.R.JENSEN, 1969, 'How much can we boost IQ and scholastic
attainment?' In Environment, Heredity and Intelligence.
Cambridge, Mass. : Harvard Educational Review.

"In 1972 [the President's Committee on Mental Retardation in the USA] announced that "using present techniques in the biomedical and behavioural sciences, it is possible to reduce the occurrence of mental retardation by 50 per cent before the end of the century".... this was a clearly incorrect prediction."
A.M. & A.D.B.CLARKE, 1986,
Journal of Child Psychology and Psychiatry.

"....the essential fact of twentieth century educational history is that egalitarian policies have failed."
A.H.HALSEY (Oxford sociologist), 1972, in A.H.Halsey,
Educational Priority. London : HMSO

"I think the Milwaukee Project is very exciting. It challenges the notion that IQ is fixed. It has been criticised by the group around Jensen and Eysenck because it represents such a threat to their position."
George ALBEE, 1976, reported by R.Trotter,
American Psychological Association Monitor 7.

"....we may be on the way to convincing even those inclined to be most sceptical, not only that mental retardation can be reversed, but that steps should be taken to ensure that it is reversed."
British Journal of Mental Subnormality 24.

"....there is every indication that the concept of family rehabilitation effectively prevents mental retardation and improves the family process.... At the same time, we are approaching the view that intervention and support for children reared with an intellectually inadequate parent and living in a disrupted family environment must continue throughout the child's school as well as pre-school years."
H.GARBER & R.HEBER (directors of the Milwaukee Project), 1980.

"Except in the most severe instance of genetic and organic impairment, the human organism is open to modifiability at all ages and stages of development."
R.FEUERSTEIN et al., 1980, Instrumental Enrichment: An Intervention Program for Cognitive Modifiability. Baltimore, MD : University Park Press.

"Expanded efforts should show that intelligence is to be attributed to a much, much greater extent to learning than has heretofore been thought or proven."
A.W.STAATS & G.L.BURNS, 1981, reporting a behaviouristic
Head Start programme, Genetic Psychology Monographs.

"Although I have scoured the research literature, I have yet to find a bona fide empirical demonstration that any psychological or educational techniques have succeeded in significantly raising children's intelligence."
A.R.JENSEN, 1983.

"The most successful interventions to improve IQ, at least in the United States, are those that attempt to change the pattern of mother-child interaction The most successful of these was devised by Phyllis Levenstein (1970, Amer.J.Orthopsychol.). In this program, a "toy demonstrator" visits mother and children at home. Usually this is done twice a week for two years, beginning when the child is between 24 and 28 months old. The visitor brings a toy or a book as a gift and demonstrates to the mother how to play games with the child, especially those involving language."
R.ORNSTEIN, 1985, Psychology.
San Diego : Harcourt Brace Jovanovich.

"High hopes of dramatic results [from Head Start programmes in the USA] were pinned on the Milwaukee Project, which involved a two-pronged approach to assisting black mothers and their babies over a 6-year period, beginning when the latter were aged 3 months. Experimental and control children were assessed too frequently, and, without doubt, test sophistication inflated all scores. The outcome in the long term has been very disappointing. IQ differences between experimental and control children remain, but, educationally, both groups are to be found at a level typical of inner city schools (Garber & Heber, 1982)."
A.M. & A.D.B.CLARKE, 1986,
Journal of Child Psychology and Psychiatry.

"It is obviously possible to control, train and educate all but the most profoundly retarded, up to a point. What has not proved possible.... is to change mentally retarded persons so that they are no longer intellectually deficient. F.Kuhlman (1940, Amer.J.Mntl Def. 45) perhaps put it best when he noted that the acquisition of skill and information was being confused with the acquisition of intelligence. ....According to the Capital Times of Madison (23 i 1981, p.6), the [Milwaukee 'Head Start'] Project was supported for 15 years (up to 1981) with funding of 14 million dollars. Since the [research] data released have been almost trivial, this expenditure must be counted as largely for the experimental treatments of the children. If 20 children were truly raised 30 points in IQ, then the cost would have been an astonishing $23 thousand per child."
H.H.SPITZ, 1986, The Raising of Intelligence.
Hillsdale, NJ : Lawrence Erlbaum Associates.

"As with Kamin, [Spitz's] criticism [of Head Start programmes] sometimes have an ad hoc quality. Yet unlike with Kamin, an overall coherence does emerge. The time that is spent with the brave new pedagogues (like that spent with psychoanalysts) is seldom correlated with the degree of measured gain; and dramatic 'IQ' gains can occur without there being any improvements in such normal correlates [of
IQ] as reading skills."
C.R.BRAND, 1987, Behaviour Research & Therapy 25.

"Some of the merchants of illusion [running Head Start programmes] were so carried away with their achievements (costing $23,000 per IQ point gained per child in the case of Heber's 'Miracle in Milwaukee) that they built themselves pine-log ranches from the research funds that poured in, and ended (two of them) serving three-year jail sentences. This would have been a small price to have paid for the secrets of how to boost intelligence; yet it is clear that the stimulating procedures-aping those of the middle class home-just do not deliver either genuine IQ gains or anything else except the skills that can help low-IQ children to cope a little with having a low IQ"
Editorial, 1987, Biology and Society 4.

"If we are seeking interventions that could raise IQ's and reduce the variance in population IQ, high IQ heritability tells us that we would have to research the effect of environmental variables that are either completely novel or else currently rare in the population in which the high IQ heritability was determined."
Robert NICHOLS, 1987, in S. & Celia Modgil, Arthur Jensen:
Consensus and Controversy
. Brighton : Falmer.

"....it is indeed true that the babies of parents who make conscientious efforts to promote the early acquisition of basic skills will show accelerated development. Moreover, providing that the parental support and encouragement is not abruptly terminated after early childhood, the effects of accelerated development will be cumulative and long-lasting."
M.J.A.HOWE, 1988, 'Is it true that everyone's child can be a
genius?' The Psychologist 1.

"Normally, IQ is quite highly correlated with scholastic performance; and if [the Milwaukee Project] training had affected general intelligence and not just the specificity of the IQ scores, the treated and untreated groups should have differed markedly in scholastic performance. But they did not. {Despite their 30 IQ-point boost, the experimental children remained low in attainment, like their controls, at around the 10th percentile.} A reasonable interpretation of this striking result is that it was the specificity of the IQ test that had been trained up, while general intelligence remained unaffected."
A.R.JENSEN, 1989, draft paper, 'Understanding g in terms of information processing.'

"Infants in the inner city of Milwaukee who were considered at risk for mental retardation because their mothers had IQs of 75 or below were assigned to Experimental(E) or Control(C) groups. From a few months of age to 6 years of age, the E group was given intensive psychological intervention designed to prevent the deceleration in the rate of mental development typically seen in such children. The gains of the E group in Stanford-Binet and Wechsler IQs, as measured against the untreated C group, were considerable, peaking at about 30 IQ points at age 6, when the special intervention ended and the children entered regular school. Thereafter, the E-C difference rapidly decreased, reaching about 10 IQ points by 14 years of age. The E-C difference in IQ was not reflected in the nonsignificant E-C difference in Reading achievement scores or the questionably significant difference in Maths achievement scores, on which, by the end of the fourth grade, the mean scores for both the E and C groups were at about the 10th percentile of the normative sample. These results are most plausibly interpreted as a specific training effect of the intervention on the item content of the IQ tests without producing a corresponding change in g, the general intelligence factor common to all cognitive tests, that the IQ ordinarily reflects in the untreated population."
A.R.JENSEN, 1989, 'Raising IQ without increasing
g? - A review of The Milwaukee Project:
Preventing Mental Retardation in Children at Risk
Developmental Review 9.

"[There was a] detailed evaluation of Head Start by the U.S. Department of Health and Human Services, abstracted in an Executive Summary (1985). Seventy-two studies provided data for meta-analyses of research into Head Start's effects on cognitive development. They were virtually unanimous in showing significant gains on cognitive tests at the termination of the program, either by contrast with control groups or on the basis of a test-retest design. A gain of 9 to 10 IQ points on average during pre-school programs is one of the most reliably established findings in the literature. Scores on tests of readiness or achievement were also significantly affected, and one year after program termination, although the IQ differences tend to have washed out, differences in the other two measures continue to be in the educationally meaningful range. However, "By the end of the second year, there are no educationally meaningful differences on any of the measures" (p.6)."
A.M. & A.D.B.CLARKE, 1989, 'The later cognitive effects of early
intervention'. Intelligence 13.

"If, as Flynn (1984, 1987) demonstrated, test performance has been improving steadily over the 27 years between the standardization of the WAIS and the WAIS-Revised, then the empirical results [of my literature survey] indicate that this improvement is largest in the average range and is much less or non-existent as you go up or down the IQ scale. Contrary to the general trend, performance has actually decreased in the retarded range, at least for the WAIS / WAIS-R comparison."
H.H.SPITZ, 1989, Intelligence 13.

"On February 28, 1989, some 200 people were killed in Venezuela during demonstrations and riots in protest against the Government's introduction of new economic austerity measures and its temporary suspension of certain civil rights."
BBC IV UK, 1 iii 1989. {In the 1980s, Venezuela had been
famous for the extravagant spending of its oil money on Head
Start programmes.}

"....we now know that genetic factors are primarily important in deciding a person's intelligence, and that Mill's father {see above} was lucky to have had a son whose genes made him receptive to such teaching as he received."
Hans EYSENCK, 1990, Rebel with a Cause. London : W.H.Allen.

"[Our results indicate that] participation in the Maharishi International University curriculum results in improvements in measures related to general intelligence."
R.W.CRANSON et al., 1991, 'Transcendental meditation
and improved performance on intelligence-related measures'.
Personality & Individual Differences 12.

"[Our] project [in Somerset] ran for 5 years with a formal evaluation of [Reuven Feuerstein's] Instrumental Enrichment (F.I.E.) on pupils, teachers, and schools being scheduled over 3 years. During this period, approximately 1,000 pupils were exposed to Instrumental Enrichment, and 30 teachers and three psychologists were trained in the program.... ....Unfortunately, in spite of the burgeoning mass of studies since the late 1970's, there is to date relatively little convincing research evidence to substantiate the claims made for F.I.E.....
[We found] no evidence of F.I.E. having any negative or positive effect on pupils' reading and mathematics attainments over the period of the study.... {There was} relatively little evidence of F.I.E. having any positive effect on pupils' cognitive abilities.... ....The Somerset study was intended as a highly detailed and searching evaluation of the application of F.I.E. to mainstream, low-achieving UK adolescents. Intriguingly, this present study failed to confirm any rise in IQ's associated with F.I.E. Moreover, there was no evidence to imply that F.I.E. had a positive influence on attainments or work study skills. However....there was some basis for mild optimism about positive attitudinal and behavioral change in the pupils, and clearer evidence of positive benefits for the teachers."
Nigel BLAGG, 1991, Can We Teach Intelligence?
Hillsdale, N.J. : Lawrence Erlbaum Associates.

"....consideration should be given to social methods of ensuring adequate vitamin and mineral intake, e.g. improvements of school meals, or additive supplementation. Considerable increases of IQ in large numbers of children would seem likely to result."
H.J.EYSENCK, 1992, The Psychologist 5, ix.

"If all the [four controlled, experimental] tests are taken as a whole, the broad conclusion is that [vitamin] supplementation has no effect on IQ"
T.A.B.SANDERS, 1992, The Psychologist 5, ix.

"....many early intervention studies, in which language stimulation was a major component, have regularly produced substantial language and cognitive gains in children from poor communities over norms and controls. The fact that gains are largely lost after the termination of the programme simply suggests that a good early foundation cannot inoculate children against later debilitating circumstances."
W.FOWLER et al., 1993, in Ciba Foundation Symposium 178, The Origins and Development of High Ability. Chichester : Wiley-Interscience.

"I'm not going to get into a genetics versus environment argument-obviously there's a genetic contribution to intelligence-but within the environmental portion, we can do a lot to help people develop and make the most of whatever abilities they have, through what Reuven Feuerstein would call mediated learning experience, or what Lev Vygotsky called internalization.... mediators....can help in the development of children's giftedness."
R.J.STERNBERG, 1993, in Ciba Symposium 178, The Origins and Development of High Ability. Chichester : Wiley-Interscience.

"We and everyone else are far from knowing whether, let alone how, any of these [pre-school, Head Start] programmes have increased intelligence."
The Bell Curve. New York : Free Press.

"The quickest way to improve your intelligence is to take a couple of puffs of a cigarette.... Nicotine has two main effects. It relaxes you and it has some sort of arousing intellectual effect. I know famous professors around the world who, when they want to write a paper, will lock themselves in a room and smoke two packets of cigarettes.... Nicotine is quite a useful and interesting substance. It's the delivery mechanism, the tar, which is bad for you. There have been a lot of studies done using nicotine patches and nicotine gum. They've used nicotine to arrest the onset of Alzheimer's disease."
Con Stough (Australian psychologist and intelligence researcher), 1995, interviewed by Noel O'Hare, The Listener (New Zealand), 28 i - 3 ii.

"Richard Nisbett, writing in The Bell Curve Wars (ed. S. Fraser, 1995), a compendium of attacks on [The Bell Curve], accuses us [Herrnstein & Murray] of being "strangely selective" in our reports about the effects of intervention, and wonders if we were "unaware of the very large literature that exists on the topic of early intervention." The "very large literature" of which we were unaware? The only study Nisbett mentions that we do not is one published in Paediatrics in 1992 which he describes as showing a nine-point IQ advantage at age three for participants in the intervention. Nisbett neglects to acknowledge the unreliability of IQ measures at age three. More decisively, Nisbett is apparently unaware that a follow-up of the same project was published in 1994, when the children were, at age five, old enough for IQ scores to begin to become interpretable. The results? The experimental group had an advantage of just 2.5 points on one measure of IQ and two-tenths of a point on another-both differences being substantively trivial and statistically insignificant. In other words, the only study in "the very large literature" that we missed does not contradict our conclusion that such interventions have provided promising leads but no more."
Charles MURRAY, 1995, Commentary 99.

(vii) What about intergenerational IQ-type changes?

"[As psychologists like William McDougall pointed out] the crust of custom and tradition has a persistent life of its own, beyond that of the individuals creating the custom. The average of intelligence may fall; yet the standards of behaviour, discrimination and sublimation
can be expected to persist for a generation or more, with only sporadic patches of decrepitude."
R.B.CATTELL, 1938, British Journal of Psychology 28.

"As Shuttleworth (1935) noted some fifty years ago, 'Even if environmental differences accounted for zero per cent, and heritability differences accounted for 100 per cent of the individual differences in intelligence, it would be true that the general level of the environment would be a most important factor determining the general level of intelligence.' The available evidence suggests, in fact, that it is the most important factor.... There is no reason to believe that the environmental changes which caused the one-standard-deviation increase in mean White IQ over a 40-year period in the U.S. reported by Flynn, and the half-standard-deviation decline in mean S.A.T. scores over a 20-year period, are best studied within the sociobiological paradigm...."
D.R.VINING, Jnr (Population Studies Center,
University of Pennsylvania), 1983.

"As regards accuracy, particularly in such subjects as spelling, arithmetic and factual topics, there has been a demonstrable decline [in English children]. There has, too, been a conspicuous relaxation among both average and abler pupils in the old-fashioned habit of sheer hard work. As one school inspector has expressed it, 'if under the rigid disciplinarians of 50 years ago the children in our classrooms were frequently overworked, under the humaner methods of today they are, all too often, underworked.' This is evident in their choice of subjects at the university. There has of late been a marked retreat from subjects like physics, chemistry and mathematics (as well as Latin and Greek) -all of which necessitate prolonged concentration, meticulous exactitude and assiduous industry-in favour of the so-called 'softer options'."
Sir Cyril BURT, 1969, 'National Survey: Health and Development in the Secondary School-Critical Notice.' Bulletin of the British Psychological Society 22.

"The barrier which prohibits 'Lamarckian' inheritance precisely protects the gene system from too rapid change under possibly capricious environmental demands."
Gregory BATESON, 1979, Mind and Nature.
London : Fontana/Collins, 1980.

"....on this particular matter of decline [in educational attainment in the USA] we are, as yet, starved of the research that would evaluate its roots. I will make an "educated guess" that the deterioration of performance is partly due to each of half-a-dozen factors, of which the three largest are: (a) a decline in the innate intelligence level due to a century-long dysgenic situation; (b) a decline in morale, due to relativistic ethics, and permissiveness which has spread from society into its schools; and (c) an increase in distractions through increased luxury, recreational time, and hours glued to TV shows."
R.B.CATTELL, 1983, in R.B.Cattell, Intelligence and National
. Washington, DC : Institute for the Study of Man.

"Data from 14 nations reveal IQ gains ranging from 5 to 25 points in a single generation. Some of the largest gains occur on culturally reduced tests and tests of fluid intelligence.... The hypothesis that best fits the results is that IQ tests do not measure intelligence but rather a correlate with a weak causal link to intelligence."
James R. FLYNN, 1987, Psychological Bulletin 101.

"There is simply no way of analyzing the Dutch data [from military
conscripts, from 1952 to 1982] without arriving at an estimate of about twenty [IQ] points [being] gained in a single generation.... heritability estimates [for IQ] should be set aside as irrelevant to explaining group differences until we can discover what went wrong."
J.R.FLYNN, 1987, in S. & Celia Modgil, Arthur Jensen: Consensus
and Controversy
. Brighton : Falmer.

"The development of the ability to perceive and think clearly is promoted by 'democratic' child-rearing in the home, by 'progressive' or 'open' educational activities in the school, and by work which demands high levels of responsibility, problem solving, and the ability to understand and influence the workings of organizations. It must be noted, however, that these same child-rearing and educational practices depress reading, writing and arithmetical ability if these abilities are measured by conventional educational tests which load heavily on reproductive ability."
J.RAVEN, 1987, 'The Raven's Progressive Matrices: U.S. norms and
their ethnic and socio-economic variation in a cross-cultural context'.

"Flynn {above} observes that massive IQ-type gains are possible without psychologists having the foggiest idea as to their cause: for example, he estimates that only 3 of the 20 IQ points gained in Holland can be attributed to rising socio-economic levels.... So why, then, do IQ scores increase across generations? One answer may be found in the increasing permissiveness, liberalism and extroversion of the 'advanced economies' which may have given their progeny a special boost on culture-fair IQ tests. Such tests are often given under time limits that hardly encourage reflection; and, of course, they were not designed to credit the assiduous application, accuracy, attention to detail, organization and feats of memory that might once have favoured the educated classes.... ....Yet what if the [worldwide] IQ rise is entirely genuine? And what if Flynn's sober view of modern educational achievements [as unlikely to have boosted intelligence] can be substantiated in times when students must, after all, be admitted to microcompute, hang-glide, speak psychobabble and smash guitars aesthetically as never before? Even this would strictly say nothing about within-generation differences-including group differences."
C.R.BRAND, 1987, Nature 328, 9 vii.

"....extroversion (or perhaps 'recklessness', indexed as it was in R.Lynn & Susan Hampson, 1977, Brit.J.soc. & clin.Psychol., by national levels of divorce, cigarette smoking, accidents, crime and illegitimacy) has been rising much faster than has culture-fair IQ" C.R.BRAND, 1987, Nature 328, 27 viii.

"Before the Second World War [the obstetric procedures of episiotomy and caesarean section] were much rarer-partly because many births were still supervised by midwives only. The technique then relied upon to enlarge the birth canal was "holding back". In other words, the baby's head (at that age not protected by a solid bony skull) was used to force the enlargement. A common result was that babies were born a nice shade of blue due to oxygen deficiency.... ....Reducing trauma to the infant in general and to the infant brain in particular is the whole goal of modern obstetric practice.... Flynn's results {see above} are thus welcome proof that modern-day obstetric practice has achieved its aims. They show that there really is less brain damage around now. In no way, however, do they impugn IQ tests. They do the opposite, in fact."
J.J.RAY, 1988, The Psychologist, xii.

"The most probable explanation of the increase in [intelligence test] scores over time....seems to be that it is due to the same variables as are increases in height and birth weight and the decline in infant mortality-that is, to improved nutrition, welfare, and hygiene. What it is about these variables that is important is as obscure for height and birth weight as it is for intellectual ability. However, the fact that such variables do have important effects on Raven's Progressive Matrices score as well as birth weight and height is shown in a remarkable study carried out in Aberdeen, Scotland, most of the results from which have never been published (Baird & Scott, 1953, Eugenics Review; Scott et al., J.Obstetrics & Gynaecology of the British Empire). In this study, calcium intake was used as an index of quality of diet, and it was shown that this has a marked impact on all three of the outcomes mentioned, and that the relationship held both within and between socio-economic groups."
J.RAVEN, 1989, Journal of Educational Measurement 26.

"We estimate that the rate of gain in IQ for Scottish children over the 22.5 years [from 1961 to 1983/4] did not exceed 2.5 IQ points per generation. This result may diverge from the reported international trend because the "massive" IQ-type gains found in other countries reflect the reliance of other investigators on multiple-choice, culture-reduced tests that tend to reward intelligent guessing and to penalize scrupulosity."
Irish Journal of Psychology.

"[Over the course of the twentieth century] changes in obstetric and paediatric practice....have enabled new-borns to live who would have died earlier in this century, presumably leading to an increase in the proportion of damaged or [what J.Ray, while trying to explain generational rises in IQ, had called] "less well functioning" brains in the population being tested. Recent evidence comparing cerebral palsy rates in 1958 and 1970 cohorts is in line with this notion. The prevalence of cerebral palsy stayed constant at 2.5/1,000 births."
Sandra ELLIOTT, 1990, The Psychologist 3.
{Yet cerebral palsy is sometimes thought to involve thromboses
occurring before the stage at which improved obstetric practices could have an effect....}

"Brand et al. (1989){above} hypothesized that [worldwide] IQ gains might be caused by altered test-taking techniques over time, techniques which confer an advantage on time-limited, multiple choice tests. As a test of their hypothesis, they predicted that IQ gains would be minimal on Wechsler verbal subtests because these eschew both multiple-choice and time pressures. They argued that Scottish WISC data confirm this prediction. However....those data show massive gains, count against their hypothesis, and support the conclusion that IQ tests cannot measure intelligence trends over time."
James R. FLYNN, 1990, Irish Journal of Psychology 11, 1.

"Following the logic of Flynn's (1990) argument {see above}-that from tiny improvements in item pass rates we can infer massive secular gains-it could be deduced, by analogy, from tiny annual percentage increases in household expenditure on bananas that we have all enjoyed massive annual percentage pay rises."
C.R.BRAND, 1990, Irish Journal of Psychology 11, 1.

"....Brand (1990) {above} makes an important mistake. In order to see the error....[he should] find a group that has scored 110 on the WISC.... get the item by item results and employ his 'method'. He will then find that he has scored them at 102 or less."
J.R.FLYNN, 1990, Irish Journal of Psychology 11, 4.

"Flynn (1990){above} claims that a tiny (1.5%) group difference in IQ-item pass-rates indicated a large (.67 s.d.) group difference in whatever the items are measuring (viz. IQ). One wonders what he can make of the widely differing percentages of Californian adolescents from different ethnic groups who meet academic entry requirements for the University of California: Orientals 39%, Whites 17%, Blacks 5%, Hispanics 5% (Walsh, 1980, Science 209). As even Californian university admission procedures will be markedly less than perfectly valid across individual cases, what still larger group differences can these already massive percentage differences be reflecting but partially? What hope Flynn gives to those who toil with feeble psychometric items that really big discoveries lie ahead!"
C.R.BRAND, 1990, Irish Journal of Psychology 11, 4.

"[Our] results do not support a vitamin supplementation effect on non-verbal IQ"
J.TODMAN et al., 1991, Personality & Individual Differences 12.

"It would have been nice to believe that the slowly rising tide of IQ scores truly signified a "smarter society." The reality seems to be much less wonderful-a society in which IQs are becoming less variable, more clustered around the mean. It is certainly good news that the lower half of the IQ distribution is doing better; it is just as certainly bad news that the gains were partly offset by slippage at the top....Slippage at the tope will have rub-off effects on science and the arts and the general level of intellectual discourse."
Daniel SELIGMAN, 1992, A Question of Intelligence:
the IQ Debate in America.
New York : Carol (Birch Lane).

"There are no general solutions because there is no such thing as a general problem."
Don SYMONS (evolutionary psychologist), quoted by K.Patel,
Times Higher Educational Supplement, 2 vi 1995.

"....the Flynn effect gives reason to conclude that intelligence is malleable after all. Herrnstein and I [in The Bell Curve] allude to that possibility without expressing much optimism about it. Moreover, even if the rise in IQ scores could be taken at face value, we would still not know how to intervene so as to manipulate it. In our view (as in Flynn's), it seems likely that most of the increase in IQ scores over time represents something besides gains in cognitive functioning. But what that something is remains unclear, and this issue is still wide open."
Charles MURRAY, 1995, Commentary 99.

"The Flynn effect shows that environmental factors can produce differences of at least [15 IQ points, over 50 years], but that effect is mysterious in its own right."
Extract from Intelligence: Knowns and Unknowns-Report of a Task Force established by the Board of the Scientific Affairs of the American Psychological Association, Chairman U. Neisser, 1995. Washington, DC : APA Science Directorate.


"We may look forward to a new generation of researchers who have no interest in oppressing a class and/or an ethnic group and, consequently, who have no interest in the genetic causes of IQ."
Attam VETTA, 1990, Cahiers de Psychologie Cognitive 10.

"In childhood, h² [broad heritability] and c² [between-family environmental variance] for IQ are of the order of .45 and .35; by late adolescence h² is around .75 and c² is quite low (zero in some studies). Substantial environmental variance remains, but it primarily reflects within-family rather than between-family differences."
Extract from Intelligence: Knowns and Unknowns-Report of a Task Force established by the Board of the Scientific Affairs of the American Psychological Association, Chairman U. Neisser, 1995. Washington, DC : APA Science Directorate.

"Although he has been attacked in the popular media as biased and bigoted, Arthur Jensen's [1981] conclusion turns out to be true: "The small handful of dissenters who argue that genetic factors play no part in IQ differences are not unlike the few persons living today who claim that the earth is flat.""
Dinesh D'SOUZA, 1995, The End of Racism. New York : Free Press.

"To turn a phrase of Leon Kamin (a well known critic of IQ tests) on
its head: no prudent person would now accept that the heritability of
IQ was zero."
N.J.MACKINTOSH, 1995, 'Insight into intelligence.' Nature 377, 19 x.


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

For more coverage of nature/nurture questions
about individual differences in intelligence, 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:

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:

A reminder of what is available in other Sections of 'P, B & S.'

Summary Index

(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.
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 vs Nurture? - Or Nature via Nurture?
6 The role of consciousness in personality and 'multiple personality'.
7 The 'folk psychology' of personality components.
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?'
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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