{"id":3375,"date":"2012-11-26T03:48:51","date_gmt":"2012-11-26T02:48:51","guid":{"rendered":"http:\/\/emilkirkegaard.dk\/en\/?p=3375"},"modified":"2012-11-26T03:50:08","modified_gmt":"2012-11-26T02:50:08","slug":"art-jensens-1969-article-how-much-can-we-boost-iq-and-scholastic-achievement","status":"publish","type":"post","link":"https:\/\/emilkirkegaard.dk\/en\/2012\/11\/art-jensens-1969-article-how-much-can-we-boost-iq-and-scholastic-achievement\/","title":{"rendered":"Art Jensen’s 1969 article: How Much Can We Boost IQ and Scholastic Achievement?"},"content":{"rendered":"

How Much Can We Boost IQ and Scholastic Achievement<\/a>? pdf<\/p>\n

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I was curious to read this article becus of all the bad things ive heard about it. however, it turned out to be not what i expected at all. its a very sensible well-researched well-written article. not at all any racist bigotry. it cud still serve as a reasonable introduction to the science of intelligence.<\/p>\n

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Occupational Correlates of Intelligence <\/em><\/span><\/p>\n

Intelligence, as we are using the term, has relevance considerably beyond the <\/span><\/p>\n

scholastic setting. This is so partly because there is an intimate relationship be-<\/span><\/p>\n

tween a society’s occupational structure and its educational system. Whether we <\/span><\/p>\n

like it or not, the educational system is one of society’s most powerful mechanisms <\/span><\/p>\n

for sorting out children to assume different roles in the occupational hierarchy. <\/span><\/p>\n

The evidence for a hierarchy of occupational prestige and desirability is unam-<\/span><\/p>\n

biguous. Let us consider three sets of numbers.2<\/span><\/p>\n

First, the Barr scale of occupations, devised in the early 1920s, provides one set of data. Lists of 120 representative occupations, each definitely and concretely described, were given to 30 psy-<\/span><\/p>\n

chological judges who were asked to rate the occupations on a scale from o to 100<\/span><\/p>\n

according to the grade of intelligence each occupation was believed to require for <\/span><\/p>\n

ordinary success. Second, in 1964, the National Opinion Research Center (NORC), <\/span><\/p>\n

by taking a large public opinion poll, obtained ratings of the prestige of a great <\/span><\/p>\n

number of occupations; these prestige ratings represent the average standing of <\/span><\/p>\n

each occupation relative to all the others in the eyes of the general public. <\/span><\/p>\n

Third, a rating of socioeconomic status (SES) is provided by the 1960 Census of <\/span><\/p>\n

Population: Classified Index of Occupations and Industries, which assigns to each <\/span><\/p>\n

of the hundreds of listed occupations a score ranging from 0 to 96 as a composite <\/span><\/p>\n

index of the average income and educational level prevailing in the occupation. <\/span><\/p>\n

The interesting point is the set of correlations among these three independent-<\/span><\/p>\n

ly derived occupational ratings. <\/span><\/p>\n

The Barr scale and the NORC ratings are correlated .91. <\/span><\/p>\n

The Barr scale and the SES index are correlated .81. <\/span><\/p>\n

The NORC ratings and the SES index are correlated .90. <\/span><\/p>\n

In other words, psychologists’ concept of the “intelligence demands” of an occu-<\/span><\/p>\n

pation (Barr scale) is very much like the general public’s concept of the prestige <\/span><\/p>\n

or “social standing” of an occupation (NORC ratings), and both are closely re-<\/span><\/p>\n

lated to an independent measure of the educational and economic status of the <\/span><\/p>\n

persons pursuing an occupation (SES index). As O. D. Duncan (1968, pp. 90-91) <\/span><\/p>\n

concludes, “. . . ‘intelligence’ is a socially defined quality and this social definition <\/span><\/p>\n

is not essentially different from that of achievement or status in the occupational <\/span><\/p>\n

sphere. . . . When psychologists came to propose operational counterparts to the <\/span><\/p>\n

notion of intelligence, or to devise measures thereof, they wittingly or unwittingly <\/span><\/p>\n

looked for indicators of capability to function in the system of key roles in the <\/span><\/p>\n

society.” Duncan goes on to note, “Our argument tends to imply that a correla-<\/span><\/p>\n

tion between IQ and occupational achievement was more or less built into IQ <\/span><\/p>\n

tests, by virtue of the psychologists’ implicit acceptance of the social standards <\/span><\/p>\n

of the general populace. Had the first IQ tests been devised in a hunting culture, <\/span><\/p>\n

‘general intelligence’ might well have turned out to involve visual acuity and <\/span><\/p>\n

running speed, rather than vocabulary and symbol manipulation. As it was, the <\/span><\/p>\n

concept of intelligence arose in a society where high status accrued to occupations <\/span><\/p>\n

involving the latter in large measure, so that what we now mean by intelligence <\/span><\/p>\n

is something like the probability of acceptable performance (given the opportu-<\/span><\/p>\n

nity) in occupations varying in social status.” <\/span><\/p>\n

 <\/p>\n

interesting<\/p>\n

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Evidence from Studies of Selective Breeding <\/span><\/em><\/p>\n

The many studies of selective breeding in various species of mammals provide <\/span><\/p>\n

conclusive evidence that many behavioral characteristics, just as most physical <\/span><\/p>\n

characteristics, can be manipulated by genetic selection (see Fuller & Thompson, <\/span><\/p>\n

1962; Scott and Fuller, 1965). Rats, for example, have been bred for maze learn-<\/span><\/p>\n

ing ability in many different laboratories. It makes little difference whether one <\/span><\/p>\n

refers to this ability as rat “intelligence,” “learning ability” or some other term\u2014 <\/span><\/p>\n

we know that it is possible to breed selectively for whatever the factors are that <\/span><\/p>\n

make for speed of maze learning. To be sure, individual variation in this com-<\/span><\/p>\n

plex ability may be due to any combination of a number of characteristics in-<\/span><\/p>\n

volving sensory acuity, drive level, emotional stability, strength of innate turning <\/span><\/p>\n

preferences, brain chemistry, brain size, structure of neural connections, speed <\/span><\/p>\n

of synaptic transmission, or whatever. The point is that the molar behavior of <\/span><\/p>\n

learning to get through a maze efficiently without making errors (i.e., going <\/span><\/p>\n

up blind alleys) can be markedly influenced in later generations by selective <\/span><\/p>\n

breeding of the parent generations of rats who are either fast or slow (“maze <\/span><\/p>\n

bright” or “maze dull,” to use the prevailing terminology in this research) in <\/span><\/p>\n

learning to get through the maze. Figure 4 shows the results of one such <\/span><\/p>\n

genetic selection experiment. They are quite typical; within only six generations <\/span><\/p>\n

of selection the offspring of the “dull” strain make 100 percent more errors in <\/span><\/p>\n

learning the maze than do the offspring of the “bright” strain (Thompson, <\/span><\/p>\n

1954). In most experiments of this type, of course, the behaviors that respond <\/span><\/p>\n

so dramatically to selection are relatively simple as compared with human in-<\/span><\/p>\n

telligence, and the experimental selection pressure is severe, so the implications <\/span><\/p>\n

of such findings for the study of human variation should not be overdrawn. <\/span><\/p>\n

Yet geneticists seem to express little doubt that many behavioral traits in <\/span><\/p>\n

humans would respond similarly to genetic selection. Three eminent geneticists <\/span><\/p>\n

(James F. Crow, James V. Neel, and Curt Stern) of the National Academy of <\/span><\/p>\n

Sciences recently prepared a “position statement,” which was generally hedged <\/span><\/p>\n

by extreme caution and understatement, that asserted: “Animal experiments <\/span><\/p>\n

have shown that almost any trait can be changed by selection. . . . A selection <\/span><\/p>\n

program to increase human intelligence (or whatever is measured by various <\/span><\/p>\n

kinds of ‘intelligence’ tests) would almost certainly be successful in some measure. <\/span><\/p>\n

The same is probably true for other behavioral traits. The rate of increase would <\/span><\/p>\n

be somewhat unpredictable, but there is little doubt that there would be prog-<\/span><\/p>\n

ress” (National Academy of Sciences, 1967, p. 893). <\/span><\/p>\n

\"\"<\/a><\/p>\n

pretty inteteresting!<\/p>\n

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For some human characteristics the degree of assortative mating is effectively <\/span><\/p>\n

zero. This is true of fingerprint ridges, for example. Men and women are ob-<\/span><\/p>\n

viously not attracted to one another on the basis of their fingerprints. Height, <\/span><\/p>\n

however, has an assortative mating coefficient (i.e., the correlation between <\/span><\/p>\n

mates) of about .30. The IQ, interestingly enough, shows a higher degree of as-<\/span><\/p>\n

sortative mating in our society than any other measurable human characteristic. <\/span><\/p>\n

I have surveyed the literature on this point, based on studies in Europe and <\/span><\/p>\n

North America, and find that the correlation between spouses’ intelligence test <\/span><\/p>\n

scores averages close to +.6o. Thus, spouses are more alike in intelligence than <\/span><\/p>\n

brothers and sisters, who are correlated about .50. <\/span><\/p>\n

As Eckland (1967) has pointed out, this high correlation between marriage <\/span><\/p>\n

partners does not come about solely because men and women are such excellent <\/span><\/p>\n

judges of one another’s intelligence, but because mate selection is greatly aided <\/span><\/p>\n

by the highly visible selective processes of the educational system and the occu-<\/span><\/p>\n

pational hierarchy. Here is a striking instance of how educational and social <\/span><\/p>\n

factors can have far-reaching genetic consequences in the population. One <\/span><\/p>\n

would predict, for example, that in preliterate or preindustrial societies as-<\/span><\/p>\n

sortative mating with respect to intelligence would be markedly less than it is <\/span><\/p>\n

in modern industrial societies. The educational screening mechanisms and socio-<\/span><\/p>\n

economic stratification by which intelligence becomes more readily visible would <\/span><\/p>\n

not exist, and other traits of more visible importance to the society would take <\/span><\/p>\n

precedence over intelligence as a basis for assortative mating. Even in our own <\/span><\/p>\n

society, there may well be differential degrees of assortative mating in different <\/span><\/p>\n

segments of the population, probably related to their opportunities for educa-<\/span><\/p>\n

tional and occupational selection. When any large and socially insulated group <\/span><\/p>\n

is not subject to the social and educational circumstances that lead to a high <\/span><\/p>\n

degree of assortative mating for intelligence, there should be important genetic <\/span><\/p>\n

consequences. One possible consequence is some reduction of the group’s ability, <\/span><\/p>\n

not as individuals but as a group, to compete intellectually. Thus probably one <\/span><\/p>\n

of the most cogent arguments for society’s promoting full equality of educational, <\/span><\/p>\n

occupational, and economic opportunity lies in the possible genetic consequences <\/span><\/p>\n

of these social institutions. <\/span><\/p>\n

 <\/p>\n

pretty high numbers?! perhaps the effect is less strong now a days?<\/p>\n

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Effects of Inbreeding on Intelligence <\/em><\/span><\/p>\n

One of the most impressive lines of evidence for the involvement of genetic fac-<\/span><\/p>\n

tors in intelligence comes from study of the effects of inbreeding, that is, the <\/span><\/p>\n

mating of relatives. In the case of polygenic characteristics the direction of the <\/span><\/p>\n

effect of inbreeding is predictable from purely genetic considerations. All in-<\/span><\/p>\n

dividuals carry in their chromosomes a number of mutant or defective genes. <\/span><\/p>\n

These genes are almost always recessive, so they have no effect on the phenotype <\/span><\/p>\n

unless by rare chance they match up with another mutant gene at the same locus <\/span><\/p>\n

on a homologous chromosome; in other words, the recessive mutant gene at a <\/span><\/p>\n

given locus must be inherited from both the father and mother in order to affect <\/span><\/p>\n

the phenotype. Since such mutants are usually defective, they do not enhance <\/span><\/p>\n

the phenotypic expression of the characteristic but usually degrade it. And for <\/span><\/p>\n

polygenic characteristics we would expect such mutants to lower the metric value <\/span><\/p>\n

of the characteristics by graded amounts, depending upon the number of paired <\/span><\/p>\n

mutant recessives. If the parents are genetically related, there is a greatly in-<\/span><\/p>\n

creased probability that the mutant recessives at given loci will be paired in the <\/span><\/p>\n

offspring. The situation is illustrated in Figure 8, which depicts in a simplified <\/span><\/p>\n

way a pair of homologous chromosomes inherited by an individual from a moth-<\/span><\/p>\n

er (M) and father (F) who are related (Pair A) and a pair of chromosomes <\/span><\/p>\n

inherited from unrelated parents (Pair B). The blackened spaces represent reces-<\/span><\/p>\n

sive genes. Although both pairs contain equal numbers of recessives, more of <\/span><\/p>\n

them are at the same loci in Pair A than in Pair B. Only the paired genes degrade <\/span><\/p>\n

the characteristics’ phenotypic value. <\/span><\/p>\n

 <\/p>\n

A most valuable study of this genetic phenomenon with respect to intelli-<\/span><\/p>\n

gence was carried out in Japan after World War II by Schuil and Neel (1965). <\/span><\/p>\n

The study illustrates how strictly sociological factors, such as mate selection, can <\/span><\/p>\n

have extremely important genetic consequences. In Japan approximately five <\/span><\/p>\n

percent of all marriages are between cousins. Schuil and Neel studied the <\/span><\/p>\n

offspring of marriages of first cousins, first cousins once removed, and <\/span><\/p>\n

second cousins. The parents were statistically matched with a control group of <\/span><\/p>\n

unrelated parents for age and socioeconomic factors. Children from the cousin <\/span><\/p>\n

marriages and the control children from unrelated parents (total N = 2,111) <\/span><\/p>\n

were given the Japanese version of the Wechsler Intelligence Scale for Children <\/span><\/p>\n

(WISC). The degree of consanguinity represented by the cousin marriages in <\/span><\/p>\n

this study had the effect of depressing WISC IQs by an average of 7.4 percent, <\/span><\/p>\n

making the mean of the inbred group nearly 8 IQ points lower than the mean of <\/span><\/p>\n

the control group. Assuming normal distributions of IQ, the effect is shown in<\/span><\/p>\n

Figure 9, and illustrates the point that the most drastic consequences of group <\/span><\/p>\n

mean differences are to be seen in the tails of the distributions. In the same study <\/span><\/p>\n

a similar depressing effect was found for other polygenic characteristics such as <\/span><\/p>\n

several anthropometric and dental variables. <\/span><\/p>\n

 <\/p>\n

The mating of relatives closer than cousins can produce a markedly greater <\/span><\/p>\n

reduction in offspring’s IQs. Lindzey (1967) has reported that almost half of a <\/span><\/p>\n

group of children born to so-called nuclear incest matings (brother-sister or <\/span><\/p>\n

father-daughter) could not be placed for adoption because of mental retarda-<\/span><\/p>\n

tion and other severe defects which had a relatively low incidence among the <\/span><\/p>\n

offspring of unrelated parents who were matched with the incestuous parents in <\/span><\/p>\n

intelligence, socioeconomic status, age, weight, and stature. In any geographi-<\/span><\/p>\n

cally confined population where social or legal regulations on mating are lax, <\/span><\/p>\n

where individuals’ paternity is often dubious, and where the proportion of half\u2013 <\/span><\/p>\n

siblings within the same age groups is high, we would expect more inadvertent <\/span><\/p>\n

inbreeding, with its unfavorable genetic consequences, than in a population in <\/span><\/p>\n

which these conditions exist to a lesser degree. <\/span><\/p>\n

 <\/p>\n

surprising that the effects are so large.<\/p>\n

 <\/p>\n

consider the effect this has on the world IQ average given data such as: http:\/\/www.consang.net\/index.php\/Global_prevalence<\/a><\/p>\n

via https:\/\/en.wikipedia.org\/wiki\/Cousin_marriage#Middle_East_2<\/a><\/p>\n

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Abdominal Decompression.<\/em> <\/span><\/p>\n

There is now evidence that certain manipulations <\/span><\/p>\n

of the intrauterine environment can affect the infant’s behavioral development <\/span><\/p>\n

for many months after birth. A technique known as abdominal decompression <\/span><\/p>\n

was invented by a professor of obstetrics (Heyns, 1963), originally for the pur-<\/span><\/p>\n

pose of making women experience less discomfort in the latter months of their <\/span><\/p>\n

pregnancy and also to facilitate labor and delivery. For about an hour a day <\/span><\/p>\n

during the last three or four months of pregnancy, the woman is placed in a de-<\/span><\/p>\n

vice that creates a partial vacuum around her abdomen, which greatly reduces <\/span><\/p>\n

the intrauterine pressure. The device is used during labor up to the moment of <\/span><\/p>\n

delivery. Heyns has applied this device to more than 400 women. Their infants, <\/span><\/p>\n

as compared with control groups who have not received this treatment, show more <\/span><\/p>\n

rapid development in their first two years and manifest an overall superiority in <\/span><\/p>\n

tests of perceptual-motor development. They sit up earlier, walk earlier, talk <\/span><\/p>\n

earlier, and appear generally more precocious than their own siblings or other <\/span><\/p>\n

children whose mothers were not so treated. At two years of age the children in <\/span><\/p>\n

Heyns’ experiment had DQs (developmental quotients) some 30 points higher <\/span><\/p>\n

than the control children (in the general population the mean DQ is 100, with <\/span><\/p>\n

a standard deviation of 15). Heyns explains the effects of maternal abdominal <\/span><\/p>\n

decompression on the child’s early development in terms of the reduction of intra-<\/span><\/p>\n

uterine pressure, which results in a more optimal blood supply to the fetus and <\/span><\/p>\n

also lessens the chances of brain damage during labor. (The intrauterine pres-<\/span><\/p>\n

sure on the infant’s head is reduced from about 22 pounds to 8 pounds.) Re-<\/span><\/p>\n

sults on children’s later IQs have not been published, but correspondence with <\/span><\/p>\n

Professor Heyns and verbal reports from visitors to his laboratory inform me that <\/span><\/p>\n

there is no evidence that the IQ of these children is appreciably higher beyond <\/span><\/p>\n

age 6 than that of control groups. If this observation is confirmed by the proper <\/span><\/p>\n

methods, it should not be too surprising in view of the negligible correlations <\/span><\/p>\n

normally found between DQs and later IQs. But since abdominal decompression <\/span><\/p>\n

results in infant precocity, one may wonder to what extent differences in intra-<\/span><\/p>\n

uterine pressure are responsible for normal individual and group differences in <\/span><\/p>\n

infant precocity. Negro infants, for example, are more precocious in develop-<\/span><\/p>\n

ment (as measured on the Bayley Scales) in their first year or two than Caucasian <\/span><\/p>\n

infants (Bayley, 1965a). Infant precocity would seem to be associated with more <\/span><\/p>\n

optimal intrauterine and perinatal conditions. This conjecture is consistent with <\/span><\/p>\n

the finding that infants whose prenatal and perinatal histories would make them <\/span><\/p>\n

suspect of some degree of brain damage show lower DQs on the Bayley Scales <\/span><\/p>\n

than normal infants (Honzik, 1962). Writers who place great emphasis on the <\/span><\/p>\n

hypothesis of inadequate prenatal care and complications of pregnancy to account <\/span><\/p>\n

for the lower average IQ of Negroes (e.g., Bronfenbrenner, 1967) are also obliged <\/span><\/p>\n

to explain why these unfavorable factors do not also depress the DQ below <\/span><\/p>\n

average in Negro infants, as do such factors as brain damage and prenatal and <\/span><\/p>\n

infant malnutrition (Cravioto, 1966). Since all such environmental factors <\/span><\/p>\n

should lower the heritability of intelligence in any segment of the population <\/span><\/p>\n

in which they are hypothesized to play an especially significant role, one way to <\/span><\/p>\n

test the hypothesis would be to compare the heritability of intelligence in that <\/span><\/p>\n

segment of the population for which extra environmental factors are hypothe-<\/span><\/p>\n

sized with the heritability in other groups for whom environmental factors are <\/span><\/p>\n

supposedly less accountable for IQ variance.<\/span><\/p>\n

 <\/p>\n

never heard of this before<\/p>\n

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Prematurity.<\/em> <\/span><\/p>\n

The literature on the relationship of premature birth to the child’s <\/span><\/p>\n

IQ is confusing and conflicting. Guilford (1967), in his recent book on The <\/span><\/p>\n

Nature of Intelligence, for example, concluded, as did Stoddard (1943), that <\/span><\/p>\n

prematurity has no effect on intelligence. Stott (1966), on the other hand, pre-<\/span><\/p>\n

sents impressive evidence of very significant IQ decrements associated with pre-<\/span><\/p>\n

maturity. Probably the most thorough review of the subject I have found, by <\/span><\/p>\n

Kushlick (1966), helps to resolve these conflicting opinions. There is little ques-<\/span><\/p>\n

tion that prematurity has the strongest known relation to brain dysfunction of <\/span><\/p>\n

any reproductive factor, and many of the complications of pregnancy are strongly <\/span><\/p>\n

associated with the production of premature children. The crucial factor in pre-<\/span><\/p>\n

maturity, however, is not prematurity per se, but low birth-weight. Birth-weight <\/span><\/p>\n

apparently acts as a threshold variable with respect to intellectual impairment. <\/span><\/p>\n

All studies of birth-weight agree in showing that the incidence of babies weighing <\/span><\/p>\n

less than 5-1\/2 lbs. increases from higher to lower social classes. But only about <\/span><\/p>\n

1 percent of the total variance of birth-weight is accounted for by socioeconomic <\/span><\/p>\n

variables. Race (Negro versus white) has an effect on birth-weight independently <\/span><\/p>\n

of socioeconomic variables. Negro babies mature at a lower birth-weight than <\/span><\/p>\n

white babies (Naylor & Myrianthopoulos, 1967). If prematurity is defined as a <\/span><\/p>\n

condition in which birth-weight is under 5-1\/2 lbs., the observed relationship <\/span><\/p>\n

between prematurity and depression of the IQ is due to the common factor of low <\/span><\/p>\n

social class. Kushlick (1966, p. 143) concludes that it is only among children <\/span><\/p>\n

having birth-weights under 3 lbs. that the mean IQ is lowered, independently <\/span><\/p>\n

of social class, and more in boys than in girls. The incidence of extreme subnor-<\/span><\/p>\n

mality is higher for children with birth-weights under 3 or 4 lbs. But when one <\/span><\/p>\n

does not count these extreme cases (IQs below 50), the effects of prematurity or <\/span><\/p>\n

low birth-weight\u2014even as low as 3 lbs.\u2014have a very weak relationship to chil-<\/span><\/p>\n

dren’s IQs by the time they are of school age. The association between very low <\/span><\/p>\n

birth-weight and extreme mental subnormality raises the question of whether <\/span><\/p>\n

the low birth-weight causes the abnormality or whether the abnormality arises <\/span><\/p>\n

independently and causes the low birth-weight. <\/span><\/p>\n

 <\/p>\n

Prematurity and low birth-weight have a markedly higher incidence among <\/span><\/p>\n

Negroes than among whites. That birth-weight differences per se are not a pre-<\/span><\/p>\n

dominant factor in Negro-white IQ differences, however, is suggested by the find-<\/span><\/p>\n

ings of a study which compared Negro and white premature children matched for <\/span><\/p>\n

birth-weight. The Negro children in all weight groups performed significantly <\/span><\/p>\n

less well on mental tests at 3 and 5 years of age than the white children of com-<\/span><\/p>\n

parable birth-weight (Hardy, 1965, p. 51). <\/span><\/p>\n

 <\/p>\n

isnt it rather that blacks hav shorter gestation times relative to whites? not that they get more premature births. well, premature compared to white standards, but thats not a good way of looking at it. one might as well say that whites have many postmature births compared to blacks.<\/p>\n

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 <\/p>\n

Birth Order.<\/em> <\/span><\/p>\n

Order of birth contributes a significant proportion of the variance in <\/span><\/p>\n

mental ability. On the average, first-born children are superior in almost every <\/span><\/p>\n

way, mentally and physically. This is the consistent finding of many studies (Altus, <\/span><\/p>\n

1966) but as yet the phenomenon remains unexplained. (Rimland [1964, pp. <\/span><\/p>\n

140-143] has put forth some interesting hypotheses to explain the superiority of <\/span><\/p>\n

the first-born.) Since the first-born effect is found throughout all social classes <\/span><\/p>\n

in many countries and has shown up in studies over the past 80 years (it was first <\/span><\/p>\n

noted by Galton), it is probably a biological rather than a social-psychological <\/span><\/p>\n

phenomenon. It is almost certainly not a genetic effect. (It would tend to make <\/span><\/p>\n

for slightly lower estimates of heritability based on sibling comparisons.) It is <\/span><\/p>\n

one of the sources of environmental variance in ability without any significant <\/span><\/p>\n

postnatal environmental correlates. No way is known for giving later-born chil-<\/span><\/p>\n

dren the same advantage. The disadvantage of being later-born, however, is very <\/span><\/p>\n

slight and shows up conspicuously only in the extreme upper tail of the distribu-<\/span><\/p>\n

tion of achievements. For example, there is a disproportionate number of first-<\/span><\/p>\n

born individuals whose biographies appear in Who’s Who and in the Encyclope-<\/span><\/p>\n

dia Britannica. <\/span><\/p>\n

 <\/p>\n

thats interesting. it immediately comes to mind that birth order has a storng effect on male homosexuality as well. so, this wud mean that male homosexuality and lower g shud be somewhat related.<\/p>\n

 <\/p>\n

see: https:\/\/en.wikipedia.org\/wiki\/Fraternal_birth_order_and_male_sexual_orientation<\/a><\/p>\n

 <\/p>\n

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 <\/p>\n

Nutrition<\/em>. <\/span><\/p>\n

Since the human brain attains 70 percent of its maximum adult weight <\/span><\/p>\n

in the first year after birth, it should not be surprising that prenatal and infant <\/span><\/p>\n

nutrition can have significant effects on brain development. Brain growth is <\/span><\/p>\n

largely a process of protein synthesis. During the prenatal period and the first <\/span><\/p>\n

postnatal year the brain normally absorbs large amounts of protein nutrients <\/span><\/p>\n

and grows at the average rate of 1 to 2 milligrams per minute (Stoch & Smythe, <\/span><\/p>\n

1963; Cravioto, 1966). <\/span><\/p>\n

 <\/p>\n

Severe undernutrition before two or three years of age, especially a lack of <\/span><\/p>\n

proteins and the vitamins and minerals essential for their anabolism, results in <\/span><\/p>\n

lowered intelligence. Stoch and Smythe (1963) found, for example, that extreme-<\/span><\/p>\n

ly malnourished South African colored children were some 20 points lower in IQ <\/span><\/p>\n

than children of similar parents who had not suffered from malnutrition. The <\/span><\/p>\n

difference between the undernourished group and the control group in DQ and <\/span><\/p>\n

IQ over the age range from 1 year to 8 years was practically constant. If under-<\/span><\/p>\n

nutrition takes a toll, it takes it early, as shown by the lower DQs at 1 year and <\/span><\/p>\n

the absence of any increase in the decrement at later ages. Undernutrition occur-<\/span><\/p>\n

ring for the first time in older children seems to have no permanent effect. Se-<\/span><\/p>\n

verely malnourished war prisoners, for example, function intellectually at their <\/span><\/p>\n

expected level when they are returned to normal living conditions. The study <\/span><\/p>\n

by Stoch and Smythe, like several others (Cravioto, 1966; Scrimshaw, 1968), also <\/span><\/p>\n

revealed that the undernourished children had smaller stature and head circum-<\/span><\/p>\n

ference than the control children. Although there is no correlation between in-<\/strong><\/span><\/span><\/p>\n

telligence and head circumference in normally nourished children<\/strong>, there is a <\/span><\/span><\/p>\n

positive correlation between these factors in groups whose numbers suffer varying <\/span><\/span><\/p>\n

degrees of undernutrition early in life. Undernutrition also increases the corre-<\/span><\/span><\/p>\n

lation between intelligence and physical stature. These correlations provide us <\/span><\/span><\/p>\n

with an index which could aid the study of IQ deficits due to undernutrition in <\/span><\/span><\/p>\n

selected populations. <\/span><\/span><\/span><\/p>\n

 <\/p>\n

this seems to hav been proven wrong. there is a correlation, but its small, about 0.20. see:<\/span><\/span><\/p>\n

Rushton, J. P., & Ankney, C. D. (2009). <\/span><\/span>Whole-brain size and general mental ability: A review<\/span><\/span><\/a>. <\/span><\/span>International Journal of Neuroscience<\/em><\/span><\/span>, <\/span><\/span>119<\/em><\/span><\/span>, 691-731.<\/span><\/span><\/p>\n

 <\/p>\n

–<\/span><\/span><\/p>\n

 <\/p>\n

Race Differences<\/em> <\/span><\/span><\/span><\/p>\n

The important distinction between the individual and the population must al-<\/span><\/span><\/span><\/p>\n

ways be kept clearly in mind in any discussion of racial differences in mental <\/span><\/span><\/span><\/p>\n

abilities or any other behavioral characteristics. Whenever we select a person for <\/span><\/span><\/span><\/p>\n

some special educational purpose, whether for special instruction in a grade\u2013 <\/span><\/span><\/span><\/p>\n

school class for children with learning problems, or for a “gifted” class with an <\/span><\/span><\/span><\/p>\n

advanced curriculum, or for college a<\/span>ttendance, or for admission to graduate <\/span><\/span><\/p>\n

training or a professional school, we are selecting an individual, and we are se-<\/span><\/span><\/p>\n

lecting him and dealing with him as an individua<\/span>l for reasons of his individual-<\/span><\/p>\n

ity. Similarly, when we employ someone, or promote someone in his occupation, <\/span><\/p>\n

or give some special award or honor to someone for his accomplishments, we are <\/span><\/p>\n

doing this to an individual. The variables of social class, race, and national origin <\/span><\/p>\n

are correlated so imperfectly with any of the valid criteria on which the above de-<\/span><\/p>\n

cisions should depend, or, for that matter, with any behavioral characteristic, <\/span><\/p>\n

that these background factors are irrelevant as a basis for dealing with individuals <\/span><\/p>\n

\u2014as students, as employees, as neighbors. Furthermore, since, as far as we know, <\/span><\/p>\n

the full range of human talents is represented in all the major races of man and <\/span><\/p>\n

in all socioeconomic levels, it is unjust to allow the mere fact of an individual’s <\/span><\/p>\n

racial or social background to affect the treatment accorded to him. All persons <\/span><\/p>\n

rightfully must be regarded on the basis of their individual qualities and merits, <\/span><\/p>\n

and all social, educational, and economic institutions must have built into them <\/span><\/p>\n

the mechanisms for insuring and maximizing the treatment of persons according <\/span><\/p>\n

to their individual behavior. <\/span><\/p>\n

 <\/p>\n

Jensen was an evil bigot, right, right? …<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Another aspect of the distribution of IQs in the Negro population is their <\/span><\/p>\n

lesser variance in comparison to the white distribution. This shows up in most <\/span><\/p>\n

of the studies reviewed by Shuey. The best single estimate is probably the estimate <\/span><\/p>\n

based on a large normative study of Stanford-Binet IQs of Negro school chil-<\/span><\/p>\n

dren in five Southeastern states, by Kennedy, Van De Riet, and White (1963). <\/span><\/p>\n

They found the SD of Negro children’s IQs to be 12.4, as compared with 16.4 in <\/span><\/p>\n

the white normative sample. The Negro distribution thus has only about 60 per-<\/span><\/p>\n

cent as much variance (i.e., SD2<\/sup>) as the white distribution. <\/span><\/p>\n

 <\/p>\n

There is an increasing realization among students of the psychology of the dis-<\/span><\/p>\n

advantaged that the discrepancy in their average performance cannot be com-<\/span><\/p>\n

pletely or directly attributed to discrimination or inequalities in education. It <\/span><\/p>\n

seems not unreasonable, in view of the fact that intelligence variation has a large <\/span><\/p>\n

genetic component, to hypothesize that genetic factors may play a part in this <\/span><\/p>\n

picture. But such an hypothesis is anathema to many social scientists. The idea <\/span><\/p>\n

that the lower average intelligence and scholastic performance of Negroes <\/span><\/p>\n

could involve, not only environmental, but also genetic, factors has indeed been <\/span><\/p>\n

strongly denounced (e.g., Pettigrew, 1964). But it has been neither contradicted <\/span><\/p>\n

nor discredited by evidence. <\/span><\/p>\n

 <\/p>\n

The fact that a reasonable hypothesis has not been rigorously proved does not <\/span><\/p>\n

mean that it should be summarily dismissed. It only means that we need more <\/span><\/p>\n

appropriate research for putting it to the test. I believe such definitive research <\/span><\/p>\n

is entirely possible but has not yet been done. So all we are left with are various <\/span><\/p>\n

lines of evidence, no one of which is definitive alone, but which, viewed all to-<\/span><\/p>\n

gether, make it a not unreasonable hypothesis that genetic factors are strongly <\/span><\/p>\n

implicated in the average Negro-white intelligence difference. The preponderance <\/span><\/p>\n

of the evidence is, in my opinion, less consistent with a strictly environmental <\/span><\/p>\n

hypothesis than with a genetic hypothesis, which, of course, does not exclude the <\/span><\/p>\n

influence of environment or its interaction with genetic factors.<\/span><\/p>\n

 <\/p>\n

1) the smaller SD might be due to bad sampling. if the sample is not representative, that might explain it. if that is the case, one shud observe some more non-normality in the data, probably with a loss of people in the low end, say -1-2 SD, so around 55-70.<\/p>\n

 <\/p>\n

2) i think the proponderance of the evidence today is really strong. so strong that a purely environmental theory cannot be rationally held.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

It has been argued by Harry and Margaret Harlow that “human beings in our <\/span><\/p>\n

world today have no more, or little more, than the absolute minimal intellec-<\/span><\/p>\n

tual endowment necessary for achieving the civilization we know today” (Harlow <\/span><\/p>\n

& Harlow, 1962, p. 34). They depict where we would probably be if man’s average <\/span><\/p>\n

genetic endowment for intelligence had never risen above the level corresponding <\/span><\/p>\n

to IQ 75: “. . . the geniuses would barely exceed our normal or average level; <\/span><\/p>\n

comparatively few would be equivalent in ability to our average high school <\/span><\/p>\n

graduates. There would be no individuals with the normal intellectual capacities <\/span><\/p>\n

essential for making major discoveries, and there could be no civilization as we <\/span><\/p>\n

know it.” <\/span><\/p>\n

 <\/p>\n

It may well be true that the kind of ability we now call intelligence was needed <\/span><\/p>\n

in a certain percentage of the human population for our civilization to have <\/span><\/p>\n

arisen. But while a small minority\u2014perhaps only one or two percent\u2014of highly <\/span><\/p>\n

gifted individuals were needed to advance civilization, the vast majority were <\/span><\/p>\n

able to assimilate the consequences of these advances. It may take a Leibnitz or <\/span><\/p>\n

a Newton to invent the calculus, but almost any college student can learn it and <\/span><\/p>\n

use it. <\/span><\/p>\n

 <\/p>\n

Since intelligence (meaning g) is not the whole of human abilities, there may <\/span><\/p>\n

be some fallacy and some danger in making it the sine qua non of fitness to play <\/span><\/p>\n

a productive role in modern society. We should not assume certain ability re-<\/span><\/p>\n

quirements for a job without establishing these requirements as a fact. How often <\/span><\/p>\n

do employment tests, Civil Service examinations, the requirement of a high school <\/span><\/p>\n

89 diploma, and the like, constitute hurdles that are irrelevant to actual perfor-<\/span><\/p>\n

mance on the job for which they are intended as a screening device? Before going <\/span><\/p>\n

overboard in deploring the fact that disadvantaged minority groups fail to clear <\/span><\/p>\n

many of the hurdles that are set up for certain jobs, we should determine whether <\/span><\/p>\n

the educational and mental test barriers that stand at the entrance to many of <\/span><\/p>\n

these employment opportunities are actually relevant. They may be relevant only <\/span><\/p>\n

in the correlational sense that the test predicts success on the job, in which case <\/span><\/p>\n

we should also know whether the test measures the ability actually required on <\/span><\/p>\n

the job or measures only characteristics that happen to be correlated with some <\/span><\/p>\n

third factor which is really essential for job performance. Changing people in <\/span><\/p>\n

terms of the really essential requirements of a given job may be much more fea-<\/span><\/p>\n

sible than trying to increase their abstract intelligence or level of performance <\/span><\/p>\n

in academic subjects so that they can pass irrelevant tests.<\/span><\/p>\n

 <\/p>\n

good point.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

How Much Can We Boost IQ and Scholastic Achievement? pdf   I was curious to read this article becus of all the bad things ive heard about it. however, it turned out to be not what i expected at all. its a very sensible well-researched well-written article. not at all any racist bigotry. it cud […]<\/p>\n","protected":false},"author":17,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1839,1921],"tags":[],"class_list":["post-3375","post","type-post","status-publish","format-standard","hentry","category-psychometics","category-sociology","entry"],"_links":{"self":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/3375","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/comments?post=3375"}],"version-history":[{"count":3,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/3375\/revisions"}],"predecessor-version":[{"id":3379,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/posts\/3375\/revisions\/3379"}],"wp:attachment":[{"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/media?parent=3375"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/categories?post=3375"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/emilkirkegaard.dk\/en\/wp-json\/wp\/v2\/tags?post=3375"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}