{"id":3500,"date":"2012-12-26T05:07:35","date_gmt":"2012-12-26T04:07:35","guid":{"rendered":"http:\/\/emilkirkegaard.dk\/en\/?p=3500"},"modified":"2012-12-26T05:07:35","modified_gmt":"2012-12-26T04:07:35","slug":"review-the-g-factor-arthur-jensen","status":"publish","type":"post","link":"https:\/\/emilkirkegaard.dk\/en\/2012\/12\/review-the-g-factor-arthur-jensen\/","title":{"rendered":"Review: The g Factor (Arthur Jensen)"},"content":{"rendered":"

The g factor, the science of mental ability – Arthur R. Jensen,<\/a> ebook download pdf free<\/p>\n

 <\/p>\n

This is a very interesting book. Without a doubt the best about intelligence that i hav read so far. I definitely recommend reading it if one is interested in psychometrics. It can serve as a long, good, but a bit dated introduction to the subject. For shorter introductions, probably Gottfredson’s why g matters<\/em> is better.<\/p>\n

 <\/p>\n

 <\/p>\n

Quotes and comments below. Red text = quotes.<\/p>\n

——-<\/p>\n

 <\/p>\n

Galton had no tests for obtaining direct measurements of cognitive ability. <\/span><\/p>\n

Yet he tried to estimate the mean levels of mental capacity possessed by different <\/span><\/p>\n

racial and national groups on his interval scale of the normal curve. His esti\u00ad<\/span><\/p>\n

mates\u2014many would say guesses\u2014were based on his observations of people of <\/span><\/p>\n

different races encountered on his extensive travels in Europe and Africa, on <\/span><\/p>\n

anecdotal reports of other travelers, on the number and quality of the inventions <\/span><\/p>\n

and intellectual accomplishments of different racial groups, and on the percent\u00ad<\/span><\/p>\n

age of eminent men in each group, culled from biographical sources. He ven\u00ad<\/span><\/p>\n

tured that the level of ability among the ancient Athenian Greeks averaged \u201c two <\/span><\/p>\n

grades\u201d higher than that of the average Englishmen of his own day. (Two grades <\/span><\/p>\n

on Galton\u2019s scale is equivalent to 20.9 IQ points.) Obviously, there is no pos\u00ad<\/strong><\/span><\/p>\n

sibility of ever determining if Galton\u2019s estimate was anywhere near correct.<\/strong> He <\/span><\/p>\n

also estimated that African Negroes averaged \u201c at least two grades\u201d (i.e., 1.39a, <\/span><\/p>\n

or 20.9 IQ points) below the English average. This estimate appears remarkably <\/span><\/p>\n

close to the results for phenotypic ability assessed by culture-reduced IQ tests. <\/span><\/p>\n

Studies in sub-Saharan Africa indicate an average difference (on culture-reduced
\nnonverbal tests of reasoning) equivalent to 1.43a, or 21.5 IQ points between <\/span><\/p>\n

blacks and whites.8 U.S. data from the Armed Forces Qualification Test (AFQT), <\/span><\/p>\n

obtained in 1980 on large representative samples of black and white youths, <\/span><\/p>\n

show an average difference of 1.36a (equivalent to 20.4 IQ points)\u2014not far <\/span><\/p>\n

from Galton\u2019s estimate (1.39a, or 20.9 IQ points).9 But intuition and informed <\/span><\/p>\n

guesses, though valuable in generating hypotheses, are never acceptable as ev\u00ad<\/span><\/p>\n

idence in scientific research. Present-day scientists, therefore, properly dismiss <\/span><\/p>\n

Galton\u2019s opinions on race. Except as hypotheses, their interest is now purely <\/span><\/p>\n

biographical and historical.<\/span><\/p>\n

 <\/p>\n

yes there is. first, one can check the historical record to look for dysgenic effects. if the british are less smart than the ancient greeks, there wud probably hav been som dysgenic effects somwher in history. still, this is not a good method, since the population groups are somwhat different.<\/p>\n

 <\/p>\n

second, soon we will know the genes that cause different levels of intelligence. we can then analyze the remains of ancient greeks to see which genes they had. this shud giv a pretty good estimate, altho not perfect since, that 1) new mutations hav com by since then, 2) som gene variants hav perhaps disappeared, 3) the difficulty of getting a representativ sample of ancient greeks to test from, 4) the problems with getting good enuf quality DNA to run tests on. still, i dont think these are impossible to overcom, and i predict that som decent estimate can be made.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

A General Factor Is Not Inevitable.<\/strong> Factor analysis is not by its nature <\/span><\/p>\n

bound to produce a general factor regardless of the nature of the correlation <\/span><\/p>\n

matrix that is analyzed. A general factor emerges from a hierarchical factor <\/span><\/p>\n

analysis if, and only if, a general factor is truly latent in the particular correlation <\/span><\/p>\n

matrix. A general factor derived from a hierarchical analysis should be based <\/span><\/p>\n

on a matrix of positive correlations that has at least three latent roots (eigen\u00ad<\/span><\/p>\n

values) greater than 1.<\/span><\/p>\n

For proof that a general factor is not inevitable, one need only turn to studies <\/span><\/p>\n

of personality. The myriad of inventories that measure various personality traits <\/span><\/p>\n

have been subjected to every type of factor analysis, yet no general factor has<\/span><\/p>\n

ever emerged in the personality domain. There are, however, a great many first- <\/span><\/p>\n

order group factors and several clearly identified second-order group factors, or <\/span><\/p>\n

\u201c superfactors\u201d (e.g., introversion-extraversion, neuroticism, and psychoticism), <\/span><\/p>\n

but no general factor. In the abilities domain, on the other hand, a general factor, <\/span><\/p>\n

g, always emerges, provided the number and variety of mental tests are sufficient <\/span><\/p>\n

to allow a proper factor analysis. The domain of body measurements (including <\/span><\/p>\n

every externally measurable feature of anatomy) when factor analyzed also <\/span><\/p>\n

shows a large general factor (besides several small group factors). Similarly, the <\/span><\/p>\n

correlations among various measures of athletic ability show a substantial gen\u00ad<\/span><\/p>\n

eral factor.<\/span><\/p>\n

 <\/p>\n

 <\/p>\n

Jensen was wrong about this, altho the significance of that is disputed afaict. see:<\/p>\n

How important is the General Factor of Personality? A General Critique<\/em> (William Revelle and Joshua Wilt), PDF<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

In jobs where assurance of competence is absolutely critical, however, such <\/span><\/p>\n

as airline pilots and nuclear reactor operators, government agencies seem to have <\/span><\/p>\n

recognized that specific skills, no matter how well trained, though essential for <\/span><\/p>\n

job performance, are risky if they are not accompanied by a fairly high level of <\/span><\/p>\n

g. For example, the TVA, a leader in the selection and training of reactor op\u00ad<\/span><\/p>\n

erators, concluded that results of tests of mechanical aptitude and specific job <\/span><\/p>\n

knowledge were inadequate for predicting an operator\u2019s actual performance on <\/span><\/p>\n

the job. A TVA task force on the selection and training of reactor operators <\/span><\/p>\n

stated: \u201c intelligence will be stressed as one of the most important characteristics <\/span><\/p>\n

of superior reactor operators.. . . intelligence distinguishes those who have <\/span><\/p>\n

merely memorized a series of discrete manual operations from those who can <\/span><\/p>\n

think through a problem and conceptualize solutions based on a fundamental <\/span><\/p>\n

understanding of possible contingencies.\u201d 161 This reminds one of Carl Bereiter\u2019s <\/span><\/p>\n

clever definition of \u201c intelligence\u201d as \u201c what you use when you don\u2019t know <\/span><\/p>\n

what to do.\u201d<\/span><\/p>\n

 <\/p>\n

funny and true<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

The causal underpinnings of mental development take place at the neurolog\u00ad<\/span><\/p>\n

ical level even in the absence of any specific environmental inputs such as those <\/span><\/p>\n

that could possibly explain mental growth in something like figure copying in <\/span><\/p>\n

terms of transfer from prior learning. The well-known \u201c Case of Isabel\u201d is a <\/span><\/p>\n

classic example.181 From birth to age six, Isabel was totally confined to a dimly <\/span><\/p>\n

lighted attic room, where she lived alone with her deaf-mute mother, who was <\/span><\/p>\n

her only social contact. Except for food, shelter, and the presence of her mother, <\/span><\/p>\n

Isabel was reared in what amounted to a totally deprived environment. There <\/span><\/p>\n

were no toys, picture books, or gadgets of any kind for her to play with. When <\/span><\/p>\n

found by the authorities, at age six, Isabel was tested and found to have a mental <\/span><\/p>\n

age of one year and seven months and an IQ of about 30, which is barely at <\/span><\/p>\n

the imbecile level. In many ways she behaved like a very young child; she had <\/span><\/p>\n

no speech and made only croaking sounds. When handed toys or other unfa\u00ad<\/span><\/p>\n

miliar objects, she would immediately put them in her mouth, as infants nor\u00ad<\/span><\/p>\n

mally do. Yet as soon as she was exposed to educational experiences she <\/span><\/p>\n

acquired speech, vocabulary, and syntax at an astonishing rate and gained six <\/span><\/p>\n

years of tested mental age within just two years. By the age of eight, she had <\/span><\/p>\n

come up to a mental age of eight, and her level of achievement in school was <\/span><\/p>\n

on a par with her age-mates. This means that her rate of mental development\u2014 <\/span><\/p>\n

gaining six years of mental age in only two years\u2014was three times faster than <\/span><\/p>\n

that of the average child. As she approached the age of eight, however, her <\/span><\/p>\n

mental development and scholastic performance drastically slowed down and <\/span><\/p>\n

proceeded thereafter at the rate of an average child. She graduated from high <\/span><\/p>\n

school as an average student.<\/span><\/p>\n

 <\/p>\n

What all this means to the g controversy is that the neurological basis of <\/span><\/p>\n

information processing continued developing autonomously throughout the six <\/span><\/p>\n

years of Isabel\u2019s environmental deprivation, so that as soon as she was exposed <\/span><\/p>\n

to a normal environment she was able to learn those things for which she was <\/span><\/p>\n

developmentally \u201c ready\u201d at an extraordinarily fast rate, far beyond the rate for <\/span><\/p>\n

typically reared children over the period of six years during which their mental <\/span><\/p>\n

age normally increases from two to eight years. But the fast rate of manifest <\/span><\/p>\n

mental development slowed down to an average rate at the point where the level <\/span><\/p>\n

of mental development caught up with the level of neurological development. <\/span><\/p>\n

Clearly, the rate of mental development during childhood is not just the result <\/span><\/p>\n

of accumulating various learned skills that transfer to the acquisition of new <\/span><\/p>\n

skills, but is largely based on the maturation of neural structures.<\/span><\/p>\n

 <\/p>\n

this reminds me of the person who suggested that we delay teaching math in schools for the same reason. it is simply more time-effective, and time is costly, both for the child who has limited freedom in the time spent in school, and for soceity becus that time cud hav been spent on teaching somthing else, or not spent at all and thus saved money on teachers.<\/p>\n

 <\/p>\n

the idea is that som math subjects takes very long to teach, say, 8 year olds, but can rapidly to taught to 12 year olds. so, using som invented numbers, the idea is that instead of spending 10 hours teaching long division to 8 year olds, we cud spend 2 hours teaching long division to 12 year olds, thus saving 8 eights that can be either used on somthing else that can be taught easily to 8 year olds, or simply freeing up the time for non-teaching activities.<\/p>\n

 <\/p>\n

see: http:\/\/www.inference.phy.cam.ac.uk\/sanjoy\/benezet\/<\/a> for the original papers<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Perhaps the most problematic test of overlapping neural elements posited by <\/span><\/p>\n

the sampling theory would be to find two (or more) abilities, say, A and B, that<\/span><\/p>\n

are highly correlated in the general population, and then find some individuals <\/span><\/p>\n

in whom ability A is severely impaired without there being any impairment of <\/span><\/p>\n

ability B. For example, looking back at Figure 5.2, which illustrates sampling <\/span><\/p>\n

theory, we see a large area of overlap between the elements in Test A and the <\/span><\/p>\n

elements in Test B. But if many of the elements in A are eliminated, some of <\/span><\/p>\n

its elements that are shared with the correlated Test B will also be eliminated, <\/span><\/p>\n

and so performance on Test B (and also on Test C in this diagram) will be <\/span><\/p>\n

diminished accordingly. Yet it has been noted that there are cases of extreme <\/span><\/p>\n

impairment in a particular ability due to brain damage, or sensory deprivation <\/span><\/p>\n

due to blindness or deafness, or a failure in development of a certain ability due <\/span><\/p>\n

to certain chromosomal anomalies, without any sign of a corresponding deficit <\/span><\/p>\n

in other highly correlated abilities.22 On this point, behavioral geneticists Will- <\/span><\/p>\n

erman and Bailey comment: \u201c Correlations between phenotypically different <\/span><\/p>\n

mental tests may arise, not because of any causal connection among the mental <\/span><\/p>\n

elements required for correct solutions or because of the physical sharing of <\/span><\/p>\n

neural tissue, but because each test in part requires the same \u2018qualities\u2019 of brain <\/span><\/p>\n

for successful performance. For example, the efficiency of neural conduction or <\/span><\/p>\n

the extent of neuronal arborization may be correlated in different parts of the <\/span><\/p>\n

brain because of a similar epigenetic matrix, not because of concurrent func\u00ad<\/span><\/p>\n

tional overlap.\u201d 22 A simple analogy to this would be two independent electric <\/span><\/p>\n

motors (analogous to specific brain functions) that perform different functions <\/span><\/p>\n

both running off the same battery (analogous to g). As the battery runs down, <\/span><\/p>\n

both motors slow down at the same rate in performing their functions, which <\/span><\/p>\n

are thus perfectly correlated although the motors themselves have no parts in <\/span><\/p>\n

common. But a malfunction of one machine would have no effect on the other <\/span><\/p>\n

machine, although a sampling theory would have predicted impaired perform\u00ad<\/span><\/p>\n

ance for both machines.<\/span><\/p>\n

 <\/p>\n

i know its only an analogy, but whether ther ar one or two motors tapping from one battery might hav an effect on their speed. that depends on the setup, i think.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Gc is most highly loaded in tests based on scholastic knowledge and cultural <\/span><\/p>\n

content where the relation-eduction demands of the items are fairly simple. Here <\/span><\/p>\n

are two examples of verbal analogy problems, both of about equal difficulty in <\/span><\/p>\n

terms of percentage of correct responses in the English-speaking general pop\u00ad<\/span><\/p>\n

ulation, but the first is more highly loaded on G f and the second is more highly <\/span><\/p>\n

loaded on Gc.<\/span><\/p>\n

 <\/p>\n

1. Temperature is to cold as Height is to<\/span><\/p>\n

(a) hot (b) inches (c) size (d) tall (e) weight<\/span><\/p>\n

2. Bizet is to Carmen as Verdi is to<\/span><\/p>\n

(a) Aida (b) Elektra (c) Lakme (d) Manon (e) Tosca<\/span><\/p>\n

 <\/p>\n

first one, i wanted to answer <small>, since <cold> is on the bottum of the scale of temperature, so i wanted somthing that was on the bottom of the scale of height. but ther is no such option, but tall is also on the scale of height, just as cold is on the scale of temperature. with no other better option, i went with (d), which was correct.<\/p>\n

 <\/p>\n

second one, however, made no sense to me. i did look for patterns in spelling, vowels, length, etc., found nothing. i then googled it. its composers and their operas.<\/p>\n

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

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

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

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

 <\/p>\n

–<\/p>\n

 <\/p>\n

Another blood variable of interest is the amount of uric acid in the blood <\/span><\/p>\n

(serum urate level). Many studies have shown it to have only a slight positive <\/span><\/p>\n

correlation with IQ. But it is considerably more correlated with measures of <\/span><\/p>\n

ambition and achievement. Uric acid, which has a chemical structure similar to <\/span><\/p>\n

caffeine, seems to act as a brain stimulant, and its stimulating effect over the <\/span><\/p>\n

course of the individual\u2019s life span results in more notable achievements than <\/span><\/p>\n

are seen in persons of comparable IQ, social and cultural background, and gen\u00ad<\/span><\/p>\n

eral life-style, but who have a lower serum urate level. High school students <\/span><\/p>\n

with elevated serum urate levels, for example, obtain higher grades than their <\/span><\/p>\n

IQ-matched peers with an average or below-average serum urate level, and, <\/span><\/p>\n

amusingly, one study found a positive correlation between university professors\u2019 <\/span><\/p>\n

serum urate levels and their publication rates. The undesirable aspect of high <\/span><\/p>\n

serum urate level is that it predisposes to gout. In fact, that is how the association <\/span><\/p>\n

was originally discovered. The English scientist Havelock Ellis, in studying the<\/span><\/p>\n

lives and accomplishments of the most famous Britishers, discovered that they <\/span><\/p>\n

had a much higher incidence of gout than occurs in the general population.<\/span><\/p>\n

Asthma and other allergies have a much-higher-than-average frequency in <\/span><\/p>\n

children with higher IQs (over 130), particularly those who are mathematically <\/span><\/p>\n

gifted, and this is an intrinsic relationship. The intellectually gifted show some <\/span><\/p>\n

15 to 20 percent more allergies than their siblings and parents. The gifted are <\/span><\/p>\n

also more apt to be left-handed, as are the mentally retarded; the reason seems <\/span><\/p>\n

to be that the IQ variance of left-handed persons is slightly greater than that of <\/span><\/p>\n

the right-handed, hence more of the left-handed are found in the lower and upper <\/span><\/p>\n

extremes of the normal distribution of IQ.<\/span><\/p>\n

 <\/p>\n

Then there are also a number of odd and less-well-established physical cor\u00ad<\/span><\/p>\n

relates of IQ that have each shown up in only one or two studies, such as vital <\/span><\/p>\n

capacity (i.e., the amount of air that can be expelled from the lungs), handgrip <\/span><\/p>\n

strength, symmetrical facial features, light hair color, light eye color, above- <\/span><\/p>\n

average basic metabolic rate (all these are positively correlated with IQ), and <\/span><\/p>\n

being unable to taste the synthetic chemical phenylthiocarbamide (nontasters are <\/span><\/p>\n

higher both in g and in spatial ability than tasters; the two types do not differ <\/span><\/p>\n

in tests of clerical speed and accuracy). The correlations are small and it is not <\/span><\/p>\n

yet known whether any of them are within-family correlations. Therefore, no <\/span><\/p>\n

causal connection with g has been established.<\/span><\/p>\n

 <\/p>\n

Finally, there is substantial evidence of a positive relation between g and <\/span><\/p>\n

general health or physical well-being.[36] In a very large national sample of high <\/span><\/p>\n

school students (about 10,000 of each sex) there was a correlation of +.381 <\/span><\/p>\n

between a forty-three-item health questionnaire and the composite score on a <\/span><\/p>\n

large number of diverse mental tests, which is virtually a measure of g. By <\/span><\/p>\n

comparison, the correlation between the health index and the students\u2019 socio\u00ad<\/span><\/p>\n

economic status (SES) was only +.222. Partialing out g leaves a very small <\/span><\/p>\n

correlation ( + .076) between SES and health status. In contrast, the correlation <\/span><\/p>\n

between health and g when SES is partialed out is +.326.<\/span><\/p>\n

 <\/p>\n

how very curius!<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Certainly psychometric tests were never constructed with the intention of <\/span><\/p>\n

measuring inbreeding depression. Yet they most certainly do. At least fourteen <\/span><\/p>\n

studies of the effects of inbreeding on mental ability test scores\u2014mostly IQ\u2014 <\/span><\/p>\n

have been reported in the literature.132′ Without exception, all of the studies show <\/span><\/p>\n

inbreeding depression both of IQ and of IQ-correlated variables such as scho\u00ad<\/span><\/p>\n

lastic achievement. As predicted by genetic theory, the IQ variance of the inbred <\/span><\/p>\n

is greater than that of the noninbred samples. Moreover, the degree to which <\/span><\/p>\n

IQ is depressed is an increasing monotonic function of the coefficient of in- <\/span><\/p>\n

breeding. The severest effects are seen in the offspring of first-degree incestuous <\/span><\/p>\n

matings (e.g., father-daughter, brother-sister); the effect is much less for first- <\/span><\/p>\n

cousin matings and still less for second-cousin matings. The degree of IQ de\u00ad<\/span><\/p>\n

pression for first cousins is about half a standard deviation (seven or eight IQ <\/span><\/p>\n

points).<\/span><\/p>\n

 <\/p>\n

In most of these studies, social class and other environmental factors are well <\/span><\/p>\n

controlled. Studies in Muslim populations in the Middle East and India are <\/span><\/p>\n

especially pertinent. Cousin marriages there are more prevalent in the higher <\/span><\/p>\n

social classes, as a means of keeping wealth in family lines, so inbreeding and <\/span><\/p>\n

high SES would tend to have opposite and canceling effects. The observed effect <\/span><\/p>\n

of inbreeding depression on IQ in the studies conducted in these groups, <\/span><\/p>\n

therefore, cannot be attributed to the environmental effects of SES that are often <\/span><\/p>\n

claimed to explain IQ differences between socioeconomically advantaged and <\/span><\/p>\n

disadvantaged groups.<\/span><\/p>\n

 <\/p>\n

These studies unquestionably show inbreeding depression for IQ and other <\/span><\/p>\n

single measures of mental ability. The next question, then, concerns the extent <\/span><\/p>\n

to which g itself is affected by inbreeding. Inbreeding depression could be <\/span><\/p>\n

mainly manifested in factors other than g, possibly even in each test\u2019s specificity. <\/span><\/p>\n

To answer this question, we can apply the method of correlated vectors to in- <\/span><\/p>\n

breeding data based on a suitable battery of diverse tests from which g can be <\/span><\/p>\n

extracted in a hierarchical factor analysis. I performed these analyses1331 for the <\/span><\/p>\n

several large samples of children born to first-and second-cousin matings in <\/span><\/p>\n

Japan, for whom the effects of inbreeding were intensively studied by geneticists <\/span><\/p>\n

William Schull and James Neel (1965). All of the inbred children and compa\u00ad<\/span><\/p>\n

rable control groups of noninbred children were tested on the Japanese version<\/span><\/p>\n

of the Wechsler Intelligence Scale for Children (WISC). The correlations among <\/span><\/p>\n

the eleven subtests of the WISC were subjected to a hierarchical factor analysis, <\/span><\/p>\n

separately for boys and girls, and for different age groups, and the overall av\u00ad<\/span><\/p>\n

erage g loadings were obtained as the most reliable estimates of g for each <\/span><\/p>\n

subtest. The analysis revealed the typical factor structure of the WISC\u2014a large <\/span><\/p>\n

g factor and two significant group factors: Verbal and Spatial (Performance). <\/span><\/p>\n

(The Memory factor could not emerge because the Digit Span subtest was not <\/span><\/p>\n

used.) Schull and Neel had determined an index of inbreeding depression on <\/span><\/p>\n

each of the subtests. In each subject sample, the column vector of the eleven <\/span><\/p>\n

subtests\u2019 g loadings was correlated with the column vector of the subtests\u2019 index <\/span><\/p>\n

of inbreeding depression (ID). (Subtest reliabilities were partialed out of these <\/span><\/p>\n

correlations.) The resulting rank-order correlation between subtests\u2019 g loadings <\/span><\/p>\n

and their degree of inbreeding depression was + .79 (p < .025). The correlation <\/span><\/p>\n

of ID with the Verbal factor loadings (independent of g) was +.50 and with the <\/span><\/p>\n

Spatial (or Performance) factor the correlation was \u2014.46. (The latter two cor\u00ad<\/span><\/p>\n

relations are nonsignificant, each with p < .05.) Although this negative corre\u00ad<\/span><\/p>\n

lation of ID with the spatial factor (independent of g) falls short of significance, <\/span><\/p>\n

the negative correlation was found in all four independent samples. Moreover, <\/span><\/p>\n

it is consistent with the hypothesis that spatial visualization ability is affected <\/span><\/p>\n

by an X-linked recessive allele.34 Therefore, it is probably not a fluke.<\/span><\/p>\n

 <\/p>\n

A more recent study1351 of inbreeding depression, performed in India, was <\/span><\/p>\n

based entirely on the male offspring of first-cousin parents and a control group <\/span><\/p>\n

of the male offspring of genetically unrelated parents. Because no children of <\/span><\/p>\n

second-cousin marriages were included, the degree of inbreeding depression was <\/span><\/p>\n

considerably greater than in the previous study, which included offspring of <\/span><\/p>\n

second-cousin marriages. The average inbreeding effect on the WISC-R Full <\/span><\/p>\n

Scale IQ was about ten points, or about two-third of a standard deviation.1361 <\/span><\/p>\n

The inbreeding index was reported for the ten subtests of the WISC-R used in <\/span><\/p>\n

this study. To apply the method of correlated vectors, however, the correlations <\/span><\/p>\n

among the subtests for this sample are needed to calculate their g loadings. <\/span><\/p>\n

Because these correlations were not reported, I have used the g loadings obtained <\/span><\/p>\n

from a hierarchical factor analysis of the 1,868 white subjects in the WISC-R <\/span><\/p>\n

standardization sample.1371 The column vector of these g loadings and the column <\/span><\/p>\n

vector of the ID index have a rank-order correlation (with the tests\u2019 reliability <\/span><\/p>\n

coefficients partialed out) of +.83 (p < .01), which is only slightly larger than <\/span><\/p>\n

the corresponding correlation between the g and ID vectors in the Japanese <\/span><\/p>\n

study.<\/span><\/p>\n

 <\/p>\n

In sum, then, the g factor significantly predicts the degree to which perform\u00ad<\/span><\/p>\n

ance on various mental tests is affected by inbreeding depression, a theoretically <\/span><\/p>\n

predictable effect for traits that manifest genetic dominance. The larger a test\u2019s <\/span><\/p>\n

g loading, the greater is the depression of the test scores of the inbred offspring <\/span><\/p>\n

of consanguineous parents, as compared with the scores of noninbred persons. <\/span><\/p>\n

The evidence in these studies of inbreeding rules out environmental variables <\/span><\/p>\n

as contributing to the observed depression of test scores. Environmental differ\u00ad<\/span><\/p>\n

ences were controlled statistically, or by matching the inbred and noninbred <\/span><\/p>\n

groups on relevant indices of environmental advantage.<\/span><\/p>\n

 <\/p>\n

pretty large effects. the footnote with the 14 studies mentioned is:<\/p>\n

 <\/p>\n

Adams & Neel, 1967; Afzal, 1988; Afzal & Sinha, 1984; Agrawal et al., 1984;<\/p>\n

Badaruddoza & Afzil, 1993; Bashi, 1977; Book, 1957; Carter, 1967; Cohen et al., 1963;<\/p>\n

Inbaraj & Rao, 1978; Neel, et al., 1970; Schull & Neel, 1965; Seemanova, 1971; Slatis<\/p>\n

& Hoene, 1961.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Semantic Verification Test.<\/strong> The SVT uses the binary response console (Fig\u00ad<\/span><\/p>\n

ure 8.3) and a computer display screen. Following the preparatory \u201c beep,\u201d a <\/span><\/p>\n

simple statement appears on the screen. The statement involves the relative <\/span><\/p>\n

positions of the three letters A, B, C as they may appear (equally spaced) in a <\/span><\/p>\n

horizontal array. Each trial uses one of the six possible permutations of these <\/span><\/p>\n

three letters chosen at random. The statement appears on the screen for three <\/span><\/p>\n

seconds, allowing more than enough time for the subject to read it. There are <\/span><\/p>\n

fourteen possible statements of the following types: \u201c A after B,\u201d \u201c C before <\/span><\/p>\n

A,\u201d \u201c A between B and C,\u201d \u201c B first,\u201d \u201c B last,\u201d \u201c C before A and B,\u201d \u201c C <\/span><\/p>\n

after B and A\u201d ; and the negative form of each of these statements, for instance, <\/span><\/p>\n

\u201c A not after B.\u201d Following the three-second appearance of one of these state\u00ad<\/span><\/p>\n

ments, the screen goes blank for one second and then one of the permutations <\/span><\/p>\n

of the letters A B C appears. The subject responds by pressing either the TRUE <\/span><\/p>\n

or FALSE button, depending on whether the positions of the letters does or does <\/span><\/p>\n

not agree with the immediately previous statement.<\/span><\/p>\n

 <\/p>\n

Although the SVT is the most complex of the many ECTs that have been <\/span><\/p>\n

tried in my lab, the average RT for university students is still less than 1 second. <\/span><\/p>\n

The various \u201c problems\u201d differ widely in difficulty, with average RTs ranging<\/span><\/p>\n

from 650 msec to 1,400 msec. Negative statements take about 200 msec longer <\/span><\/p>\n

than the corresponding positive statements. MT, on the other hand, is virtually <\/span><\/p>\n

constant across conditions, indicating that it represents something other than <\/span><\/p>\n

speed of information processing.<\/span><\/p>\n

 <\/p>\n

The overall median RT and RTSD as measured in the SVT each correlates <\/span><\/p>\n

about \u2014.50 with scores on the Raven\u2019s Advanced Progressive Matrices given <\/span><\/p>\n

without time limit. The average RT on the SVT also shows large differences <\/span><\/p>\n

between Navy recruits and university students,1201 and between academically <\/span><\/p>\n

gifted children and their less gifted siblings.1211 The fact that there is a within- <\/span><\/p>\n

families correlation between RT and IQ indicates that these variables are intrin\u00ad<\/span><\/p>\n

sically and functionally related.<\/span><\/p>\n

 <\/p>\n

One study20 reveals that the average processing time for each of the fourteen <\/span><\/p>\n

types of SVT statements in university students predicts the difficulty level of <\/span><\/p>\n

the statements (in terms of error responses) in children (third-graders) who were <\/span><\/p>\n

given the SVT as a nonspeeded paper-and-pencil test. While the SVT is of such <\/span><\/p>\n

trivial difficulty for college students that individual differences are much more <\/span><\/p>\n

reliably reflected by RT rather than by errors, the SVT items are relatively <\/span><\/p>\n

difficult for young children. Even when they take the SVT as a nonspeeded <\/span><\/p>\n

paper-and-pencil test, young children make errors on about 20 percent of the <\/span><\/p>\n

trials. (The few university students who made even a single error under these <\/span><\/p>\n

conditions, given as a pretest, were screened out.) The fact that the rank order <\/span><\/p>\n

of the children\u2019s error rates on the various types of SVT statements closely <\/span><\/p>\n

corresponds to the rank order of the college students\u2019 average RTs on the same <\/span><\/p>\n

statements indicates that item difficulty is related to speed of processing, even <\/span><\/p>\n

when the test is nonspeeded.<\/span><\/p>\n

 <\/p>\n

It appears that if information exceeds a critical level of complexity for the in\u00ad<\/span><\/p>\n

dividual, the individual\u2019s speed of processing is too slow to handle the infor\u00ad<\/span><\/p>\n

mation all at once; the system becomes overloaded and processing breaks <\/span><\/p>\n

down, with resulting errors, even for nonspeeded tests on which subjects are <\/span><\/p>\n

told to take all the time they need. There are some items in Raven\u2019s Advanced <\/span><\/p>\n

Matrices, for example, that the majority of college students cannot solve with <\/span><\/p>\n

greater than chance success, even when given any amount of time, although the <\/span><\/p>\n

problems do not call for the retrieval of any particular knowledge. As already <\/span><\/p>\n

noted, the scores on such nonspeeded tests are correlated with the speed of in\u00ad<\/span><\/p>\n

formation processing in simple ECTs that are easily performed by all subjects <\/span><\/p>\n

in the study.<\/span><\/p>\n

 <\/p>\n

interesting test. the threshold hypothesis is also interesting for makers of IQ tests.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

There are many other kinds of simple tasks that do not resemble the con\u00ad<\/span><\/p>\n

tents of conventional psychometric tests but that have significant correlations <\/span><\/p>\n

with IQ. Many studies have confirmed Spearman\u2019s finding that pitch discrim\u00ad<\/span><\/p>\n

ination is g-loaded, and other musical discriminations, in duration, timbre, <\/span><\/p>\n

rhythmic pattern, pitch interval, and harmony, are correlated with IQ, indepen\u00ad<\/span><\/p>\n

dently of musical training.28 The strength of certain optical illusions is also <\/span><\/p>\n

significantly related to IQ.1291 Surprisingly, higher-IQ subjects experience cer\u00ad<\/span><\/p>\n

tain illusions more strongly than subjects with lower IQ, probably because <\/span><\/p>\n

seeing the illusion implies a greater amount of mental transformation of the <\/span><\/p>\n

stimulus, and tasks that involve transformation of information (e.g., backward <\/span><\/p>\n

digit span) are typically more g loaded than tasks involving less transforma\u00ad<\/span><\/p>\n

tion of the input (e.g., forward digit span). The positive correlation between <\/span><\/p>\n

IQ and susceptibility to illusions is consistent with the fact that susceptibility <\/span><\/p>\n

to optical illusions also increases with age, from childhood to maturity, and <\/span><\/p>\n

then decreases in old age\u2014the same trajectory we see for raw-score perform\u00ad<\/span><\/p>\n

ance on IQ tests and for speed and intraindividual consistency of RT in ECTs. <\/span><\/p>\n

The speed and consistency of information processing generally show an in\u00ad<\/span><\/p>\n

verted U curve across the life span.<\/span><\/p>\n

 <\/p>\n

interesting.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Jensen mentions the https:\/\/en.wikipedia.org\/wiki\/Yerkes-Dodson_law<\/a><\/p>\n

interesting. i link to Wikipedia since i think its explanation of the law is better than Jensens, who just briefly mentions it.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

[…Localized damage to the brain <\/span><\/p>\n

areas that normally subserve one of these group factors can leave the person <\/span><\/p>\n

severely impaired in the expression of the abilities loaded on the group factor, <\/span><\/p>\n

but with little or no impairment of abilities that are loaded on other group factors <\/span><\/p>\n

or on g.]<\/span><\/p>\n

 <\/p>\n

A classic example of this is females who are born with a chromosomal anom\u00ad<\/span><\/p>\n

aly known as Turner\u2019s syndrome.1701 Instead of having the two normal female <\/span><\/p>\n

sex chromosomes (designated XX), they lack one X chromosome (hence are <\/span><\/p>\n

designated XO). Provided no spatial visualization tests are included in the IQ <\/span><\/p>\n

battery, the IQs of these women (and presumably their levels of g) are normally <\/span><\/p>\n

distributed and virtually indistinguishable from that of the general population. <\/span><\/p>\n

Yet their performance on all tests that are highly loaded on the spatial- <\/span><\/p>\n

visualization factor is extremely low, typically borderline retarded, even in <\/span><\/p>\n

Turner\u2019s syndrome women with verbal IQs above 130. It is as if their level of <\/span><\/p>\n

g is almost totally unreflected in their level of performance on spatial tasks.<\/span><\/p>\n

 <\/p>\n

It is much harder to imagine the behavior of persons who are especially <\/span><\/p>\n

deficient in all abilities involving g and all of the major group factors, but have <\/span><\/p>\n

only one group factor that remains intact. In our everyday experience, persons <\/span><\/p>\n

who are highly verbal, fluent, articulate, and use a highly varied vocabulary, <\/span><\/p>\n

speaking with perfect syntax and appropriate expression, are judged to be of at <\/span><\/p>\n

least average or probably superior IQ. But there is a rare and, until recently, <\/span><\/p>\n

little-known genetic anomaly, Williams syndrome,1711 in which the above-listed <\/span><\/p>\n

characteristics of high verbal ability are present in persons who are otherwise <\/span><\/p>\n

severely mentally deficient, with IQs averaging about 50. In most ways, Wil\u00ad<\/span><\/p>\n

liams syndrome persons appear to behave with no more general capability of <\/span><\/p>\n

getting along in the world than most other persons with similarly low IQs. As<\/span><\/p>\n

adults, they display only the most rudimentary scholastic skills and must live <\/span><\/p>\n

under supervision. Only their spoken verbal ability has been spared by this <\/span><\/p>\n

genetic defect. But their verbal ability appears to be \u201c hollow\u201d with respect to <\/span><\/p>\n

g. They speak in complete, often complex, sentences, with good syntax, and <\/span><\/p>\n

even use unusual words appropriately. (They do surprisingly well on the Pea\u00ad<\/span><\/p>\n

body Picture Vocabulary Test.) In response to a series of pictures, they can tell <\/span><\/p>\n

a connected and fully elaborated story, accompanied by appropriate, if somewhat <\/span><\/p>\n

exaggerated, emotional expression. Yet they have exceedingly little ability to <\/span><\/p>\n

reason, or to explain or summarize the meaning of what they say. On most <\/span><\/p>\n

spatial ability tests they generally perform on a par with Down syndrome persons <\/span><\/p>\n

of comparable IQ, but they also differ markedly from Down persons in peculiar <\/span><\/p>\n

ways. Williams syndrome subjects are more handicapped than IQ-matched <\/span><\/p>\n

Down subjects in figure copying and block designs.<\/span><\/p>\n

 <\/p>\n

Comparing Turner\u2019s syndrome with Williams syndrome obviously suggests <\/span><\/p>\n

the generalization that a severe deficiency of one group factor in the presence <\/span><\/p>\n

of an average level of g is far less a handicap than an intact group factor in the <\/span><\/p>\n

presence of a very low level of g.<\/span><\/p>\n

 <\/p>\n

never heard of Williams syndrome befor.<\/p>\n

 <\/p>\n

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

 <\/p>\n

–<\/p>\n

 <\/p>\n

The correlation of IQ with grades and achievement test scores is highest (.60 <\/span><\/p>\n

to .70) in elementary school, which includes virtually the entire child population <\/span><\/p>\n

and hence the full range of mental ability. At each more advanced educational <\/span><\/p>\n

level, more and more pupils from the lower end of the IQ distribution drop out, <\/span><\/p>\n

thereby restricting the range of IQs. The average validity coefficients decrease <\/span><\/p>\n

accordingly: high school (.50 to .60), college (.40 to .50), graduate school (.30 <\/span><\/p>\n

to .40). All of these are quite high, as validity coefficients go, but they permit <\/span><\/p>\n

far less than accurate prediction of a specific individual. (The standard error of <\/span><\/p>\n

estimate is quite large for validity coefficients in this range.)<\/span><\/p>\n

 <\/p>\n

interesting. one thing that i hav been thinking about is that my GPA thruout my life has always been a bit abov average, but not close to the top. given that the intelligence requirement for each new step on the way thru the school system increases, one wud hav expected a drop in GPA, but no such thing happened. in fact, its the other way around. my GPA is the danish elementary school is 9.3 (9th grade) the average is ~8.1. this includes grades from non-intellectual subjects such as the ‘subject’ of having a nice hand-writing (yes seriusly). in 10th grade my average was 8.7, and the average is ~6.6. the max is 13 in all cases, altho normally grades abov 11 wer not given.<\/p>\n

 <\/p>\n

in gymnasiet (high school equiv.ish), my GPA was 7.8 and the average is 7.0. the slightly slower grades is becus the system was changed from a 13-step to a 7-step scale. and for comparison reasons, one can note that i went to HTX which has lower grades. the percentile level is 65th<\/a>.<\/p>\n

 <\/p>\n

my university grades befor dropping out of filosofy were rather good, lots of 10’s, but i dont know the average, so cant compare. i suspect they were abov average again.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Unless an individual has made the transition from word reading to reading <\/span><\/p>\n

comprehension of sentences and paragraphs, reading is neither pleasurable nor <\/span><\/p>\n

practically useful. Few adults with an IQ of eighty (the tenth percentile of the<\/span><\/p>\n

overall population norm) ever make the transition from word reading skill to <\/span><\/p>\n

reading comprehension. The problem of adult illiteracy (defined as less than a <\/span><\/p>\n

fourth-grade level of reading comprehension) in a society that provides an ele\u00ad<\/span><\/p>\n

mentary school education to virtually its entire population is therefore largely a <\/span><\/p>\n

problem of the lower segment of the population distribution of g. In the vast <\/span><\/p>\n

majority of people with low reading comprehension, the problem is not word <\/span><\/p>\n

reading per se, but lack of comprehension. These individuals score about the <\/span><\/p>\n

same on tests of reading comprehension even if the test paragraphs are read <\/span><\/p>\n

aloud to them by the examiner. In other words, individual differences in oral <\/span><\/p>\n

comprehension and in reading comprehension are highly correlated.12’1<\/span><\/p>\n

 <\/p>\n

80.. but the american black average is only about 85. is it really true that ~37% of them ar too dull to learn to read properly? compared with ~10% of whites.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Virtually every type of work calls for behavior that is guided by cognitive <\/span><\/p>\n

processes. As all such processes reflect g to some extent, work proficiency is g <\/span><\/p>\n

loaded. The degree depends on the level of novelty and cognitive complexity <\/span><\/p>\n

the job demands. No job is so simple as to be totally without a cognitive com\u00ad<\/span><\/p>\n

ponent. Several decades of empirical studies have shown thousands of correla\u00ad<\/span><\/p>\n

tions of various mental tests with work proficiency. One of the most important <\/span><\/p>\n

conclusions that can be drawn from all this research is that mental ability tests <\/span><\/p>\n

in general have a higher success rate in predicting job performance than any <\/span><\/p>\n

other variables that have been researched in this context, including (in descend\u00ad<\/span><\/p>\n

ing order of average predictive validity) skill testing, reference checks, class <\/span><\/p>\n

rank or grade-point average, experience, interview, education, and interest meas\u00ad<\/span><\/p>\n

ures.1221 In recent years, one personality constellation, characterized as \u201c consci\u00ad<\/span><\/p>\n

entiousness,” has emerged near the top of the list (just after general mental <\/span><\/p>\n

ability) as a predictor of occupational success.<\/span><\/p>\n

 <\/p>\n

reminds me that i ought to look into this field of psychology. its called I\/O psychology<\/a>. som time back i talked with a phd (i think) on 4chan who studied that area. he said that if he had his way, he wud just rely on g alone to predict job performance, training etc. he recommended me a textbook, which i found on the internet.<\/p>\n

 <\/p>\n

Psychology Applied to Work, An Introduction to Industrial and Organizational Psychology – Paul M. Muchinsky<\/p>\n

 <\/p>\n

it seems decent.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

A person cannot perform a job successfully without the specific knowledge <\/span><\/p>\n

required by the job. Possibly such job knowledge could be acquired on the job <\/span><\/p>\n

after a long period of trial-and-error learning. For all but the very simplest jobs, <\/span><\/p>\n

however, trial-and-error learning is simply too costly, both in time and in errors. <\/span><\/p>\n

Job training inculcates the basic knowledge much more efficiently, provided that <\/span><\/p>\n

later on-the-job experience further enhances the knowledge or skills acquired in <\/span><\/p>\n

prior job training. Because knowledge and skill acquisition depend on learning, <\/span><\/p>\n

and because the rate of learning is related to g, it is a reasonable hypothesis that<\/span><\/p>\n

g should be an effective predictor of individuals\u2019 relative success in any specific <\/span><\/p>\n

training program.<\/span><\/p>\n

 <\/p>\n

The best studies for testing this hypothesis have been performed in the armed <\/span><\/p>\n

forces. Many thousands of recruits have been selected for entering different <\/span><\/p>\n

training programs for dozens of highly specialized jobs based on their perform\u00ad<\/span><\/p>\n

ance on a variety of mental tests. As the amount of time for training is limited, <\/span><\/p>\n

efficiency dictates assigning military personnel to the various training schools <\/span><\/p>\n

so as to maximize the number who can complete the training successfully and <\/span><\/p>\n

minimize the number who fail in any given specialized school. When a failed <\/span><\/p>\n

trainee must be rerouted to a different training school better suited to his apti\u00ad<\/span><\/p>\n

tude, it wastes time and money. Because the various schools make quite differing <\/span><\/p>\n

demands on cognitive abilities, the armed services employ psychometric re\u00ad<\/span><\/p>\n

searchers to develop and validate tests to best predict an individual\u2019s probability <\/span><\/p>\n

of success in one or another of the various specialized schools.<\/span><\/p>\n

 <\/p>\n

 <\/p>\n

one is tempted to say \u201dcommon sense\u201d, but apparently, only the military dares to do such things.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

A rough analogy may help to make the essential point. Suppose that for some <\/span><\/p>\n

reason it was impossible to measure persons\u2019 heights directly in the usual way, <\/span><\/p>\n

with a measuring stick. However, we still could accurately measure the length <\/span><\/p>\n

of the shadow cast by each person when the person is standing outdoors in the <\/span><\/p>\n

sunlight. Provided everyone\u2019s shadow is measured at the same time of day, at <\/span><\/p>\n

the same day of the year, and at the same latitude on the earth\u2019s surface, the <\/span><\/p>\n

shadow measurements would show exactly the same correlations with persons\u2019 <\/span><\/p>\n

weight, shoe size, suit or dress size, as if we had measured everyone directly <\/span><\/p>\n

with a yardstick; and the shadow measurements could be used to predict per\u00ad<\/span><\/p>\n

fectly whether or not a given person had to stoop when walking through a door <\/span><\/p>\n

that is only 5 \u2018\/2 -feet high. However, if one group of persons\u2019 shadows were <\/span><\/p>\n

measured at 9:00 a .m . and another group\u2019s at 10:00 a .m ., the pooled measure\u00ad<\/span><\/p>\n

ments would show a much smaller correlation with weight and other factors <\/span><\/p>\n

than if they were all measured at the same time, date, and place, and the meas\u00ad<\/span><\/p>\n

urements would have poor validity for predicting which persons could walk <\/span><\/p>\n

through a 5 ‘\/2 -foot door without stooping. We would say, correctly, that these <\/span><\/p>\n

measurements are biased. In order to make them usefully accurate as predictors <\/span><\/p>\n

of a person\u2019s weight and so forth, we would have to know the time the person\u2019s <\/span><\/p>\n

shadow was measured and could then add or subtract a value that would adjust <\/span><\/p>\n

the measurement so as to make it commensurate with measurements obtained <\/span><\/p>\n

at some other specific time, date, and location. This procedure would permit the <\/span><\/p>\n

standardized shadow measurements of height, which in principle would be as <\/span><\/p>\n

good as the measurements obtained directly with a measuring stick.<\/span><\/p>\n

 <\/p>\n

Standardized IQs are somewhat analogous to the standardized shadow meas\u00ad<\/span><\/p>\n

urements of height, while the raw scores on IQ tests are more analogous to the <\/span><\/p>\n

raw measurements of the shadows themselves. If we naively remain unaware <\/span><\/p>\n

that the shadow measurements vary with the time of day, the day of the year, <\/span><\/p>\n

and the degrees of latitude, our raw measurements would prove practically <\/span><\/p>\n

worthless for comparing individuals or groups tested at different times, dates, <\/span><\/p>\n

or places. Correlations and predictions could be accurate only within each unique <\/span><\/p>\n

group of persons whose shadows were measured at the same time, date, and <\/span><\/p>\n

place. Since psychologists do not yet have the equivalent of a yardstick for <\/span><\/p>\n

measuring mental ability directly, their vehicles of mental measurement\u2014IQ <\/span><\/p>\n

scores\u2014are necessarily \u201c shadow\u201d measurements, as in our height analogy, al\u00ad<\/span><\/p>\n

beit with amply demonstrated practical predictive validity and construct validity <\/span><\/p>\n

within certain temporal and cultural limits.<\/span><\/p>\n

 <\/p>\n

 <\/p>\n

interesting. however, biologically based tests shud allow for absolut measurement, say tests based on RT in ECTs, or tests based on the amount of mylianation in the brain, or brain ph levels, brain size via brain imaging scans if we can make them better measurements of g, etc.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

Many possible factors determine whether a person passes or fails a particular <\/span><\/p>\n

test item. Does the person understand the item at all (e.g., \u201cWhat is the sum of <\/span><\/p>\n

all the latent roots of a 7 X 7 R matrix?\u201d )? Has the person acquired the specific <\/span><\/p>\n

knowledge called for by the item (e.g., \u201cWho wrote Faust?”), or perhaps has <\/span><\/p>\n

he acquired it in the past and has since forgotten it? Did the person really know <\/span><\/p>\n

the answer, but just couldn\u2019t recall it at the moment of being tested? Does the <\/span><\/p>\n

item call for a cognitive skill the person either never acquired or has forgotten <\/span><\/p>\n

through disuse (e.g., \u201c How much of a whole apple is two-thirds of one-half of <\/span><\/p>\n

the apple?\u201d )? Does the person understand the problem and know how to solve <\/span><\/p>\n

it, but is unable to do it within the allotted time limit (e.g., substituting the <\/span><\/p>\n

corresponding letter of the alphabet for each of the numbers from one to twenty- <\/span><\/p>\n

six listed in a random order in one minute)? Or even when there is a liberal <\/span><\/p>\n

time limit does the person give up on the item or just guess at the answer <\/span><\/p>\n

prematurely, perhaps because the item looks too complicated at first glance (e.g., <\/span><\/p>\n

\u201c If it takes six garden hoses, all running for three hours and thirty minutes to <\/span><\/p>\n

fill a tank, how many additional hoses would be needed to fill the tank in thirty <\/span><\/p>\n

minutes?\u201d )?<\/span><\/p>\n

 <\/p>\n

1) dunno<\/p>\n

2) Goethe<\/p>\n

3) 2\/3*1\/2=4\/6*3\/6=12\/36=1\/3<\/p>\n

4) #hose*time=tank size<\/p>\n

6*3.5=21<\/p>\n

21 is the size of the tank<\/p>\n

21=0.5*#hose, solve #hose<\/p>\n

42=#hose<\/p>\n

42-6=36<\/p>\n

36 more hoses<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

The only study I have found that investigated whether there has been a secular<\/span><\/p>\n

change (over thirty years) in the heritability of g-loaded test scores concluded <\/span><\/p>\n

that \u201c the results revealed no unambiguous evidence for secular trends in the <\/span><\/p>\n

heritability of intelligence test scores.\u201d 1351 However, the heritability coefficients <\/span><\/p>\n

(based on twenty-two same-age cohort samples of MZ and DZ male twins born <\/span><\/p>\n

in Norway between 1930 and 1960) showed some statistically reliable nonlinear <\/span><\/p>\n

trends over the thirty-year period, as shown in Figure 10.2. The overall trend <\/span><\/p>\n

line goes equally down-up-down-up with heritability coefficients ranging from <\/span><\/p>\n

slightly above .80 to slightly below .40. The heritability coefficient was the same <\/span><\/p>\n

for the cohort born in 1930 as for the cohort born in 1960 (for both, h2 = .80). <\/span><\/p>\n

The authors offer only weak ad hoc speculations about possible causes of this <\/span><\/p>\n

erratic fluctuation of h2 across 22 points in time.<\/span><\/p>\n

 <\/p>\n

the hole is the german occupation of norway. the data from the 30s make sense to me, the depression wud result in civil unrest and the changing up of society. after a period of such, heritabilities shud stabilize again, as seen in the after war period. i dont understand the 50s down swing in heritability.<\/p>\n

 <\/p>\n

so, i thought it might be somthing economic. i gathered GDP data, and looked at the data. nope, not true.<\/p>\n

 <\/p>\n

http:\/\/www.norges-bank.no\/pages\/77409\/p1_c6.xlsx<\/a><\/p>\n

 <\/p>\n

data from 1901 to 2000 looks like this:<\/p>\n

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

gdp norway 50s<\/a><\/p>\n

 <\/p>\n

doesnt fit with the GDP hypothesis at all, except for missing data in the war.<\/p>\n

 <\/p>\n

i dunno, perhaps http:\/\/www.newsinenglish.no\/2010\/06\/16\/the-50s-in-norway-werent-so-nifty\/<\/a><\/p>\n

 <\/p>\n

the authors of the study that found the drop in heritability also dont know \u201dWe are, however, quite at a loss in explaining the dip from about 1950 to 1954. Thus, we feel that the best strategy at present is to leave the issue of secular trends open. \u201d<\/p>\n

On the question of secular trends in the heritability of intelligence scores A study of Norwegian twins<\/a><\/p>\n

–<\/p>\n

 <\/p>\n

Head Start.<\/strong> The federal preschool intervention known as Head Start, which <\/span><\/p>\n

has been in continual existence now since 1964, is undoubtedly the largest- <\/span><\/p>\n

scale, though not the most intensive, educational intervention program ever un\u00ad<\/span><\/p>\n

dertaken, with an annual expenditure over $2 billion. The program is aimed at <\/span><\/p>\n

improving the health status and the learning and social skills of preschoolers <\/span><\/p>\n

from poor backgrounds so they can begin regular school more on a par with <\/span><\/p>\n

children from more privileged backgrounds. The intervention is typically short\u00ad<\/span><\/p>\n

term, with various programs lasting anywhere from a few months to two years.<\/span><\/p>\n

 <\/p>\n

The general conclusion of the hundreds of studies based on Head Start data <\/span><\/p>\n

is that the program has little, if any, effect on IQ or scholastic achievement that <\/span><\/p>\n

endures beyond more than two to three years after exposure to Head Start. The <\/span><\/p>\n

program does, however, have some potential health benefits, such as inoculations <\/span><\/p>\n

of enrollees against common childhood diseases and improved nutrition (by <\/span><\/p>\n

school-provided breakfast or lunch). The documented behavioral effects are less <\/span><\/p>\n

retention-in-grade and lower dropout rates. The cause(s) of these effects are <\/span><\/p>\n

uncertain. Because eligible children were not randomly enrolled in Head Start, <\/span><\/p>\n

but were selected by parents and program administrators, these scholastic cor\u00ad<\/span><\/p>\n

relates of Head Start are uninterpretable from a causal standpoint. Selection, <\/span><\/p>\n

rather than direct causation by the educational intervention itself, could be the <\/span><\/p>\n

explanation of Head Start\u2019s beneficial outcomes.<\/span><\/p>\n

 <\/p>\n

crazy amount of money spent for som slight health benefits. perhaps ther is a cheaper way to get such benefits.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

The Milwaukee Project.<\/strong> Aside from Head Start, this is the most highly <\/span><\/p>\n

publicized of all intervention experiments. It was the most intensive and exten\u00ad<\/span><\/p>\n

sive educational intervention ever conducted for which the final results have <\/span><\/p>\n

been published.55 It was also the most costly single experiment in the history of <\/span><\/p>\n

psychology and education\u2014over $14 million. In terms of the highest peak of <\/span><\/p>\n

IQ gains for the seventeen children in the treatment condition (before the gains <\/span><\/p>\n

began to vanish), the cost was an estimated $23,000 per IQ point per child.<\/span><\/p>\n

 <\/p>\n

holy shit. even tho i think iv seen this figur befor (in The g Factor<\/em><\/a> by Chris Brand).<\/p>\n

 <\/p>\n

Jensen also doesnt mention the end of the project, but Wikipedia does:<\/p>\n

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

 <\/p>\n

<\/a><\/a>The Milwaukee Project’s claimed success was celebrated in the popular media and by famous psychologists. However, later in the project Rick Heber, the principal investigator, was discharged from the University of Wisconsin\u2013Madison and convicted and imprisoned for large-scale abuse of federal funding for private gain. Two of Heber’s colleagues in the project were also convicted for similar abuses. The project’s results were not published in any refereed scientific journals, and Heber did not respond to requests from colleagues for raw data and technical details of the study. Consequently, even the existence of the project as described by Heber has been called into question. Nevertheless, many college textbooks in psychology and education have uncritically reported the project’s results.<\/span>[3]<\/a>[4]<\/a><\/p>\n

 <\/p>\n

this reminds me why open data is necessary in science.<\/p>\n

 <\/p>\n

–<\/p>\n

 <\/p>\n

[The Abecedarian Early Intervention Project.]<\/span><\/p>\n

Both the T and C groups (each with about fifty subjects) were given age- <\/span><\/p>\n

appropriate mental tests (Bayley, Stanford-Binet, McCarthy, WPPSI) at <\/span><\/p>\n

six-month intervals from age six months to sixty months. The important com\u00ad<\/span><\/p>\n

parisons here are the mean T-C differences at each testing. (Because the test <\/span><\/p>\n

scores do not have the same factor composition across this wide age range, <\/span><\/p>\n

the absolute scores of the T group alone are not as informative of the efficacy <\/span><\/p>\n

of the intervention as are the mean T-C differences.) At every testing from six <\/span><\/p>\n

months to five years of age, the T group outperformed the C group, and the <\/span><\/p>\n

overall average T-C difference (103.3 \u2014 95.5 = 7.8 IQ points) was highly <\/span><\/p>\n

significant (p < .001). Peculiarly, however, the largest T-C differences (aver\u00ad<\/span><\/p>\n

aging fifteen IQ points) occurred between eighteen and thirty-six months of <\/span><\/p>\n

age and then declined during the last two years of intervention. At sixty <\/span><\/p>\n

months, the average T-C difference was 7.5 IQ points. This decrease might <\/span><\/p>\n

simply reflect the fact that with the children\u2019s increasing age the tests become <\/span><\/p>\n

increasingly more g-Ioaded. The tests used before two or three years of age <\/span><\/p>\n

measure mainly perceptual-motor functions that have relatively little g satura\u00ad<\/span><\/p>\n

tion. Only later does g becomes the predominant component of variance in <\/span><\/p>\n

IQ. In follow-up studies at eight and twelve years of age, the T-C difference <\/span><\/p>\n

on the WISC-R was about five IQ points,1571 a difference that has remained up <\/span><\/p>\n

to age fifteen. At the last reported testing, the T-C difference was 4.6 IQ <\/span><\/p>\n

points, or a difference of 0.35ct. Scholastic achievement test scores showed a <\/span><\/p>\n

somewhat larger effect of the intervention up to age fifteen.1571 The interven\u00ad<\/span><\/p>\n

tion effect on other criteria of the project\u2019s success was demonstrated by the <\/span><\/p>\n

decreased percentage of children who repeated at least one grade by age <\/span><\/p>\n

twelve (T = 28 percent, C = 55 percent) and the percentage of children with <\/span><\/p>\n

borderline or retarded intelligence (IQ < 85) (T = 12.8 percent, C = 44.2 <\/span><\/p>\n

percent).1561<\/span><\/p>\n

 <\/p>\n

Thus this five-year program of intensive intervention beginning in early in\u00ad<\/span><\/p>\n

fancy increased IQ (at age fifteen years) by about five points. Judging from a <\/span><\/p>\n

comparable gain in scholastic achievement, the effect had broad transfer, sug\u00ad<\/span><\/p>\n

gesting that it probably raised the level of g to some extent. The finding that <\/span><\/p>\n

the T subjects did better than the C subjects on a battery of Piaget\u2019s tests of <\/span><\/p>\n

conservation, which reflect important stages in mental development, is further <\/span><\/p>\n

evidence. The Piagetian tests are not only very different in task demands from <\/span><\/p>\n

anything in the conventional IQ tests used in the conventional assessments, but <\/span><\/p>\n

are also highly g loaded.1571 The mean T-C difference on the Piagetian conser\u00ad<\/span><\/p>\n

vation tests was equal to 0.33a (equivalent to five IQ points). Assuming that <\/span><\/p>\n

the instructional materials in the intervention program did not closely resemble <\/span><\/p>\n

Piaget\u2019s tests, it is a warranted conclusion that the intervention appreciably <\/span><\/p>\n

raised the Level of g.<\/span><\/p>\n

 <\/p>\n

im still skeptical as to the g effects. id like to see the data about them as adults, and a larger sample size.<\/p>\n

 <\/p>\n

again, Wikipedia has mor on the issue, both positiv and negativ:<\/p>\n

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

<\/a>Significant findings<\/span><\/h2>\n

<\/a><\/a><\/a> Follow-up assessment of the participants involved in the project has been ongoing. So far, outcomes have been measured at ages 3, 4, 5, 6.5, 8, 12, 15, 21, and 30.<\/span>[5]<\/a> The areas covered were <\/span>cognitive functioning<\/a>, academic skills, <\/span>educational attainment<\/a>, <\/span>employment<\/a>, <\/span>parenthood<\/a>, and social adjustment. The significant findings of the experiment were as follows:<\/span>[6]<\/a>[7]<\/a><\/p>\n

Impact of child care\/preschool on reading and math achievement, and cognitive ability, at age 21:<\/span><\/p>\n