Saturday, January 24, 2009

Psychometrics links

Retired physicist Bob Williams writes: "... I have studied psychometrics and intelligence research for about 17 years and have gotten to know almost all of the current researchers through my membership in the International Society for Intelligence Research. I attend the conferences and discuss the recent studies with the people who have done them."

He sent me the following interesting links:

Summary of research on heritability of intelligence

Diminishing influence of g at high end of ability

Summary of research on evolution of human intelligence


From Williams' notes on ISIR 2007: a discussion with James Flynn:

The interviewer was David Lubinski (Vanderbilt). He started the interview by asking Flynn to tell us about his life. From that point on, Lubinski only managed to get in a dozen or so words. Once the camera started, Flynn launched into an enthusiastic discussion of himself and his ideas. He made a favorable impression from the start by telling us that he grew up in a Catholic family and has become a serious atheist. He also immediately told us of his well known (socialist) political orientation and did not ever attempt to disconnect his political notions from his thoughts about intelligence and the secular rise that bears his name. Flynn speaks clearly and with a loud voice, which was well suited for the interview and later became something of a tool for overpowering people with whom he disagreed. In spite of this, I found him to be very likable, smart, and complicated. He occasionally took positions that were diametrically opposed and admitted that he had done so.

Flynn mentioned his first article (1984), showing a 14 point gain over 30 years (I may have gotten the span wrong, but I think this is correct). In 1987 he published a paper that showed the largest gains were on the Raven’s tests. He has found little, if any, gain in vocabulary. It is well known that FE (Flynn Effect) gains have been greatest in tests of abstract reasoning and least in tests that relate to scholastic items. This contrast immediately suggests that the FE gains have not been g loaded, since g loaded gains would necessarily boost all cognitive tasks. Flynn has not discussed this. I asked him what portion of the gains were g loaded and he went into his history discussion, then finally said “I don’t know.”

Flynn has approached the FE as a matter to be discussed qualitatively, without the support of carefully constructed research studies. Throughout his talk (this was an interview, but it turned into a speech), he described intelligence as a factor with historical variability. His debate with Charles Murray is available on the web and contains the same illustrations that he used in the “interview.” His bottom line is that test items have become easier over time, not because people are more intelligent, but because the items being tested have taken on a more central role in their lives. This makes sense with some test items (vocabulary, for example, but that is one area where he has found little increase), but is not at all apparent with respect to other test items, some of which are unrelated to daily experiences (just look at the list of subtests used in the W-J III).

He mentioned reaction time tests and simply discarded them as not important. This is not so easy to accept, given that a battery of RT tests can produce a very highly g loaded discrimination, yet chronometric measures have not been shown to change over decades. Meanwhile, Flynn was positive about the future of brain imaging and seemed willing to accept future results, even if they support causation that is opposite of his preference. He expects that such research will ultimately find a physiological seat of g. I fully agree, but also find this comment to be in conflict with his arguments from the Dickens-Flynn paper (Heritability Estimates Versus Large Environmental Effects: The IQ Paradox Resolved).

Interestingly, Flynn does not believe that the FE will narrow the B-W IQ gap. Some environmentalists have argued that it will, but no evidence has surfaced to show that after decades of rise, the FE has actually narrowed the gap.

Flynn admitted to having been fired twice and explained that those events prompted him to move to New Zealand. He claims to have defended Larry Summers, James Watson, and Chris Brand. ...In these areas, Flynn shows himself to be both honest and inconsistent. He is inherently likable and extraverted, although I remain of the opinion that he is less interested in discussion than in lecturing. I talked to him for a while at a reception and found him to be pleasant, polite, and sharp.

During his commentary, Flynn said that he favored affirmative action. In fact, he showed a strong interest in finding ways to help blacks overcome various obstacles. When Gottfredson questioned him about affirmative action, he said he is not a fanatic on the subject and admitted that it is unfair to whites. He said that, when employers want to hire a black worker, they are generally unconcerned with whether the employee is outstanding or average.

He attributed at least some of the FE gains to decreasing family size and noted that it cannot go much lower. When I had a chance to talk to him, I asked what portion of the FE gains he believes are g loaded. After repeating his historical perspective, he said “I don’t know.”

From notes on ISIR 2008

Jan te Nijenhuis

The Flynn effect in Korea

• United States FE rate, 3 points per decade.
• Scandinavia, recent slight reversal (IQ decrease).
• Estonia, recent gains.
• Japan, for those born from 1940 to 1965, 7.7 points per decade.
• Korea and Japan, same gains.
• Korea experienced an explosion in education and height of 1.5 to 2.0 SD.

The study involved two formats. One was to use single Raven’s test comparisons for two groups for 1952 and 1982. The other was to test a single group with two tests that were normed 30 years apart. The Koreans gained at about the same rate as did the Japanese, but delayed by 20 to 30 years. The gains have not yet leveled off or reversed.


Some useful references on this topic:

The Structure and Measurement of Intelligence

Genius: the natural history of creativity,

both by Hans Eysenck.

The g-factor, by Arthur Jensen

61 comments:

Anonymous said...

Wonder if there ever existed a measurable "reverse Flynn" effect, where IQ falls down in a scenario such as less and less people attending university (or even high school) over a long period of time.

Steve Hsu said...

According to one of the 2008 papers: Scandinavia, recent slight reversal (IQ decrease).

Anonymous said...

What did they attribute the slight fall in IQ scores to?

Steve Hsu said...

I would say no one really understands the causes of the Flynn effect right now. Likely causes: nutrition, schooling, smaller family size, etc.

Anonymous said...

If nutrition is a huge factor, it would be retrospectively interesting to see changes in the Flynn effect over the time period of Nazi occupation in Europe and other similar cases where food was severely restricted deliberately.

For smaller family sizes, I can't really think of a direct connection other than maybe families putting more resources per kid, than in a larger families.

I suspect schooling could possibly be a big factor. Before world war 2, kids could stop attending school after the 8th grade in many places. (Back then, a written entrance examination was required here for high school admissions).

What other causes have been investigated and/or conjectured? One I can think of offhand could possibly be the environment a kid grows up in, such as a kid who lives up the gang banger lifestyle and a life of crime vs. a kid who puts effort into their studies and stays away from crime, drugs, etc ...

Anonymous said...

For the case of a reverse Flynn effect in Denmark, a 2005 article by Teasdale and Owen states in the abstract:

"we here report intelligence test results from over 500,000 young Danish men, tested between 1959 and 2004, showing that performance peaked in the late 1990s, and has since declined moderately to pre-1991 levels. A contributing factor in this recent fall could be a simultaneous decline in proportions of students entering 3-year advanced-level school programs for 16–18 year olds."

Anonymous said...

"His bottom line is that test items have become easier over time, not because people are more intelligent, but because the items being tested have taken on a more central role in their lives."

Duhhhhhhhhh.

Steve. Have you read The Federalist Papers, Shakespeare, Milton, Henry James, etc.

There are not fewer such people today. There are none. SAT verbal scores have declined. If verbal intellignece has not declined, it's variance has.

Your author on IQ heritability gives no figures for parent child IQ raised apart? You might be surprised how low it is.

Anonymous said...

How low the correlation is, that is.

Anonymous said...

to 1:12 PM Anonymous

I've only read Shakespeare.

Do kids study Shakespeare at all these days?

Carson C. Chow said...

Steve,

What about Flynn's explanation of more abstraction in modern life coupled with the mentor effect?

I think the Flynn effect supports the notion that we really do Bayesian inference and deductive logic is something that must be learned and thus could improve as the demands for this type of thinking has increased. The plateau and decrease in Scandinavia is indicative that once abstraction has saturated our lives, there is no place to go but down:).

Anonymous said...

Would Steve explain why the correlation of MZA IQs isn't squared to estimate heritability?

Steve Hsu said...

Carson:

I guess I would lump that in with more schooling -- i.e., experiences which train students to solve certain types of IQ test problems, whether in the classroom or in modern life.

But nutrition is almost certainly a component. That would neatly explain the huge gains in Korea/Japan. Japan had a reasonably high level of education pre-WWII (roughly comparable to European countries), but nutrition just after the war was quite bad. Korea was devastated after their war.

Anonymous said...

"But nutrition is almost certainly a component."

Nutrition is certainly NOT a factor. Nutrition would elevate performance on ALL tests.

Apparently Steve had really bad nutrition growing up.

Steve Hsu said...

"Would Steve explain why the correlation of MZA IQs isn't squared to estimate heritability?"

Oops, I missed this when I answered Carson's comment.

I can't think of a way to explain this without algebra (can someone else)?

See this reference on twins studies, Eqn. (3.5) and p.103:

http://ibgwww.colorado.edu/workshop2006/cdrom/HTML/book2004a.pdf


Re: "Nutrition is certainly NOT a factor. Nutrition would elevate performance on ALL tests."

I guess you have a point, but isn't it possible some faculties are more impacted by malnutrition than others?

Anonymous said...

"He also immediately told us of his well known (socialist) political orientation and did not ever attempt to disconnect his political notions from his thoughts about intelligence and the secular rise that bears his name."

There seems to be a misunderstanding among conservatives and liberals that a higher heritability for IQ (given the prevailing variance in environments) somehow supports a conservative ideology.

In a eugenic state, like Cyprus in Brave New World, economic inequality could not be maintained for long.

Gross economic inequality can be maintained only with doublethink.

1. The elite is composed of the hardest working most self- sacrificing, blah, blah, blah.

2. The elite is composed of the genetically superior.

Anonymous said...

Of course it's possible.

It's also possible the feeble-minded Eastern-European Jews whose decendants run the US were malnourished.

Is the difference between Boers and British South Africans due to nutrition even in part (farmers vs urban)?

It is not appreciated that whatever the genetic endowment, an environment my be contrived or may exist to make an imbecile.

Perhaps this is not well appreciated because at the same time no environment is enough to make a genius.

Anonymous said...

Sorry, your refernce requires too much work for me.

The correlation for MZA twins indicates that the variance in IQ is reduced by .85^2 = 70% when genes are "held constant", right?

Anonymous said...

Sorry, your refernce requires too much work for me.

The correlation for MZA twins indicates that the variance in IQ is reduced by .85^2 = 70% when genes are "held constant", right?

Ben said...

"It's also possible the feeble-minded Eastern-European Jews whose decendants run the US were malnourished."

Are you referring to the claim in Gould's 'Mismeasure of Man' about Goddard finding some immigrants were feeble-minded? That claim is a cannard. Goddard never found that Jews as a group did poorly, and there is no evidence the tests were used in passing the 1924 Immigration Act (see, Franz Samelson (1975, 1982), Snyderman & Herrnstein 1983).

Also see Dan Seligman's 'A Question of Intelligence'.

Anonymous said...

OK. But the Boer British difference is not a canard, and it still exists, although it is smaller than it used to be.

The Dutch test higher than the British.

If anyone tries to explain this biologically, they are silly.

The Boers are also poor compared to the British South Africans.

Anonymous said...

Of course not Jews as a group. Immigrant Jews from Eastern Europe. America's first Jews were from Western Europe.

Anonymous said...

When I talked to Flynn, about 6 weeks ago, he agreed with me that the secular changes in IQ will ultimately be shown to be the sum of a number of different variables. FWIW, Ted Nettlebeck agreed to the same thing.

Flynn showed that the nutritional gains argument had a weakness. Lynn argued that height gains were due to improved nutrition and that they happened over the same time span as the IQ score gains. Flynn showed that there was little correlation between periods of height gain and IQ score increases. I don't know if he had the proper time adjustments on the data. Another small problem with the nutrition argument is that there has not been a study showing the content of iron, iodine, folate, etc. in the diet as a function of the test score gains. So far, these are the only food intake factors that have been connected to intelligence (see my article on heritability).

Schooling may be a factor, but it is probably not a big one. Scores on scholastic test items have decreased at the same time that scores on other test items increased. The FE has also been shown to be present in pre-school children, which doesn't leave much room for educational influence.

The family size factor is due to the decrease in mean IQ as a function of birth order. The drop is relatively small, but there is a larger decrease between the first born and second born, followed by a slight decrease for each additional child. It is obvious that a decrease in average family size would cause an increase in mean IQ.

It is important that the FE exists pretty much on a national level. It may be going up in one country and down in another. It can be out of synch, as has happened in Korea and Japan.

When I asked John Raven about the gains on the Raven's tests, he said he didn't know if they were g loaded or not, but added that the tests measure something that is important to intelligence in a practical sense. The problem here is that it is g loading that matters. Most studies that have attempted to measure the g loading of the gains have shown little or no loading.
--Bob Williams--

Ben said...

Some comments by Linda Gottfredson on Flynn's 2007 book 'What is Intelligence': (most of Gottfredson's articles are available on her faculty page http://www.udel.edu/educ/gottfredson/reprints/index.html)

"Although Flynn does not discuss the matter, there is no evidence that g itself has increased, let alone by strictly cultural factors. He can make his case for the latter only by denying that the empirical phenomenon of g is relevant, specifically, by seeming to reduce it to a collection of independent components for which he can generate separate explanations. Only in this way can he neuter the incontrovertible evidence for g’s existence as a highly replicable empirical phenomenon, its correlations with many aspects of brain physiology, the distributed nature of g-related brain activity, and the strong genetic basis of both g and brain physiology (Gottfredson, 1997; Jung & Haier, 2007)—all of which undercut a strictly cultural explanation for rising IQ scores...


Flynn rules out biological influences on brain physiology for explaining rising IQs by appealing to the very sorts of evidence that would seem to confirm their importance. Specifically, he eliminates nutrition as a possible cause of rising IQ test performance by noting that the trends for height do not seem consistent, in his view, with the disproportionate gains in IQ in some countries at the lower end of the IQ distribution. However, the very fact that height and other biological traits have changed in tandem with overall increases in IQ in many countries would seem to exclude the strictly cultural explanation that Flynn favors, no matter how fecund the “social multipliers” that he and William Dickens postulate (Mingroni, 2007, p. 812 )...




"I agree with Flynn that it is intriguing that subtest averages have not changed in tandem with their g loadings. If g itself were rising over time, one would expect the most g loaded tests to show the largest increases in raw scores. Because g constitutes the core of all mental abilities, one could construe these contrary results as evidence that it is not g that is not increasing, but perhaps one of the subsidiary factors captured by IQ tests but independent of g (e.g., see Carroll’s, 1993, the 3-stratum hierarchical model, which illustrates how abilities differ primarily in their empirically-determined generality of application across task domains)."

http://www.cato-unbound.org/2007/11/08/linda-s-gottfredson/shattering-logic-to-explain-the-flynn-effect/

Anonymous said...

Bob Williams is a rediculous person.

If he'd ever met someone with an IQ of < 60, he would know that IQ tests do not measure Bushmen's or Pygmies' intelligence.

Why Bob is the variance for black IQ lower than for white despite greater genetic diversity among blacks? The simple answer is that giving a Bushman an IQ test is like giving Bob Williams a physics word problem test written in Tagalog. The tests' validity is culture bound.

What silly people like Bob Williams do not understand:

There are many IQ tests, and their results can disagree by a lot. The Raven's and SB correlation has been measured at < .7.

An IQ test could be designed that was valid for Bushmen and Pygmies.
It might include spear-chucking.
I would not be surprised if Bob did very poorly on this test.

The heritability of IQ is not on fixed number. It depends on the variabilility of the environment.

Pygmy/Bushman IQs may have validity among Pygmies/Bushmen, but comparing Pygmy/Bushman scores and white American scores is comparing apples and oranges.

Ben said...

"Of course not Jews as a group. Immigrant Jews from Eastern Europe."

Here is Rushton's comment on that. He seems to be suggesting that the group wasn't representative even of Eastern European immigrants (The Errors and Omissions of the Revised Edition of S. J. Gould's The Mismeasure of Man (1996) http://psychology.uwo.ca/faculty/rushton_pubs.htm)
:

"By 1913, Goddard had translated the Binet test into English and arranged, over a two-and-a-half-month period, for it to be given to a subset of Jewish, Hungarian, Italian, and Russian immigrants "preselected as being neither 'obviously feeble-minded' nor 'obviously normal'" (Goddard, 1917, p. 244, emphasis added). Among this "unrepresentative" group (178 subjects in all), the tests successfully categorized 83% of the Jews, 80% of the Hungarians, 79% of the Italians, and 87% of the Russians. Goddard (1917) explicitly did not assert that 80% of Russians, Jews, or any immigrant group in general were feeble minded nor that the figures were representative of all immigrants from those nations. Nor did he claim that the feeblemindedness he was measuring was due to heredity. The vast majority of the many immigrants going through Ellis Island were never given mental tests. Nor was a random sample of any national group of immigrants ever tested. The only study by Goddard involving the testing of immigrants begins with the following sentence: "This is not a study of immigrants in general but of six small highly selected groups... "(1917, p. 243)."

Anonymous said...

That's fine.

What about the Boers?

http://books.google.com/books?id=PSRaJFu8c-YC&pg=PA551&lpg=PA551&dq=afrikaans+speakers+iq&source=web&ots=SjWGVFWwZR&sig=SBOmeFP6AYeyK5qRBo1PJUQESyc&hl=en&sa=X&oi=book_result&resnum=1&ct=result

Scroll up!

Gould was a Jew and a public intellectual and therefore untustworthy on anything relating to Jews. But have the Askenazi Jews always been so smart? Are there any studies from before WW II? I have read many post WWII and the results vary. Scores are higher, but sometimes by no more than the Orientals.

Anonymous said...

The gentiles speculating on Ashkenzi IQ, must know nothing about Judaism.

Rabbinic Judaism is a scholastic culture.

The North African Jews occupied a similar place in North Africa that the Ashkenazim occupy in the US, UK, Australia, Russia, etc. French Sephardic Jews have done well.

The Sephardic Ashkenazic difference can be explained by a difference in culture. The Sephardic Jews depended much more on the Shulchan Aruch. Study of the Talmud was not as important.

Ben said...

"The gentiles speculating on Ashkenzi IQ, must know nothing about Judaism."

Admittedly, I don't know a lot about Judaism. I have seen the interesting paper by Cochran, Hardy & Harpending, (2006): "Natural History of Ashkenazi Intelligence" (PDF). Journal of Biosocial Science 38(5):659-693 SEP 2006. I think Steven Pinker for one thinks their explanation is fairly plausible. I see they've also just released a book 'The 10,000 year explosion' which mentions the paper (the10000yearexplosion.com/).

http://homepage.mac.com/harpend/.Public/AshkenaziIQ.jbiosocsci.pdf

Anonymous said...

If Pinker really thinks that, he knows too little about the religion of his forebears.

Pharisaic = rabbinic Judaism makes a cult out of studying the Torah endlessly (mitzvah Talmud Torah). Judaism is the exegetical religion par excellence.

There is no comparison in any other culture.

Jewish intellectual achievement and the high verbal component is EXACTLY what would be expected from such a culture.

Rediculous people like Bob Williams and the UU authors assume there is a biology behind all human differences. Is there a large study of Jews adopted at birth by non-Jews?

Ben said...

Here's what Pinker say in New Republic, basically that it's a testable hypothesis that could be proved incorrect.

"C H&H, then, have provided prima facie evidence for each of the hypotheses making up their theory. But all the hypotheses would have to be true for the theory as a whole to be true--and much of the evidence is circumstantial, and the pivotal hypothesis is the one for which they have the least evidence. Yet that hypothesis is also the most easily falsifiable. By that criterion, the CH&H story meets the standards of a good scientific theory, though it is tentative and could turn out to be mistaken."

http://pinker.wjh.harvard.edu/articles/media/2006_06_17_thenewrepublic.html

Note that Cochran and Harpending's thesis about Ashkenazi Jewish IQ is subject to a cheap, simple experimental test: see whether heterozygotes for the diseases have higher IQs than their non-carrier siblings. Yet, years later, the study still hasn't been done because it's too non-PC.

Similarly, a few years ago David Rowe proposed an experimental design that could have offered evidence for or against genetically mediated group IQ differences. The response was a number of articles screaming about how the experiment must never be done. Vast quantities of money are spent on anti-racism measures, officials, and research (e.g. stereotype threat and implicit bias), but the funding agencies and IRBs won't let a few hundred thousand dollars be spent on a hugely powerful test that is easily feasible with current methods.

http://www.gnxp.com/blog/2006/11/david-rowes-final-paper.php

Anonymous said...

"Note that Cochran and Harpending's thesis about Ashkenazi Jewish IQ is subject to a cheap, simple experimental test: see whether heterozygotes for the diseases have higher IQs than their non-carrier siblings. Yet, years later, the study still hasn't been done because it's too non-PC."

Wrong.

The intellectual culture of the Ashkenazim may benefit some genotypes more than others. How these genotypes fare outside that culture is the dispositive test.

All it takes is Jews adopted at birth by non-Jews and tested before being informed of their Jewishness. Testing at age ten would be sufficient whether they knew they were Jews or not.

Black children adopted by white parents have higher IQs than their birth mothers. The IQ difference may decrease as the black children grow up, but this may be attributed to their discovering their blackness.

I'm not an "environmentalist", but many on the other side are just as stupid as Gould. There's no other word for it. As anyone knows who isn't a psychologist, psychology attracts the least able minds.

At any rate, Jews are an exception to the brain size IQ correlation. Jews have smaller heads than NW Europeans.

Anonymous said...

From your Rowe link:

"The measures of individual ancestry would then by compared with IQ scores and other measures to control for social/cultural confounding (Rowe suggests skin color)"

In a manner of speaking it says that if you're half white but have dark skin the only reason why your IQ would be higher than your all black ancestor is your white genes. Rediculous.

Why not compare American blacks and Bahamian, Jamaican, Brazillian, etc. blacks?

Ben said...

"Black children adopted by white parents have higher IQs than their birth mothers. The IQ difference may decrease as the black children grow up, but this may be attributed to their discovering their blackness."

This is at odds with the information on maturation rates though? For instance, Rushton has pointed out that African's mature earlier(shorter gestation period too), asians mature later.. As the pre-frontal cortex develops as people mature wouldn't that also explain the widening of the gap?

All sorts of measures show larger heritability at age 17 than at age 3 for example, not just IQ.

In fact, this very point has been discussed previously on this blog:

"One is that the heritability of IQ rises with age--that is to say, the extent to which genetics accounts for differences in IQ among individuals increases as people get older. Studies comparing identical and fraternal twins, published in the past decade by a group led by Thomas J. Bouchard, Jr., of the University of Minnesota and other scholars, show that about 40 percent of IQ differences among preschoolers stems from genetic differences but that heritability rises to 60 percent by adolescence and to 80 percent by late adulthood. With age, differences among individuals in their developed intelligence come to mirror more closely their genetic differences. It appears that the effects of environment on intelligence fade rather than grow with time."

http://infoproc.blogspot.com/2005/12/physics-still-pulls-them-in.html

Also, transracial adoption studies have been discussed on gnxp.

"Contrary to "culture" theory, the ethnic academic gaps are almost identical for transracially adopted children, and to the extent they are different they go in the opposite direction predicted by culture theory. The gap between whites and Asians fluctuated from 19 to .09 in the NAEP data while the gap in the adoption data is from 1/3 to 3 times larger. This is consistent with the Sue and Okazaki paper above which showed that contrary to popular anecdotes, the values that lead to higher academic grades are actually found more often in white homes. In other words Asian-Americans perform highly despite their Asian home cultural environment not because of it. And though the sample is meager, I find it interesting that the gap between the black and white adopted children was virtually identical (within just 4-6 points) to the gap between whites and blacks in the general population, just like in the Scarr adoption study.


[1] Clark, E. A., & Hanisee, J. (1982). Intellectual and adaptive
performance of Asian children in adoptive American settings.
Developmental Psychology, 18, 595–599.

Frydman, M., & Lynn, R. (1989). The intelligence of Korean children
adopted in Belgium. Personality and Individual Differences, 12, 1323–1325.

Winick, M., Meyer, K. K., & Harris, R. C. (1975). Malnutrition and
environmental enrichment by early adoption. Science, 190, 1173–1175."

http://www.gnxp.com/MT2/archives/004064.html

Ben said...

"I'm not an "environmentalist", but many on the other side are just as stupid as Gould. There's no other word for it. As anyone knows who isn't a psychologist, psychology attracts the least able minds."

Heh, I'm not sure many people would say Arthur Jensen was anything other than exceptionally able!

In any case, the paper on Ashkenazi
Jewish intelligence wasn't by psychologists. Here is a comment from one of the authors, Greg Cochran on the Marginal Revolution site:

"Suppose that there are N balls in an urn, of which m are red. The hypergeometric distribution describes the probability that exactly k balls are red in a sample of p distinct balls drawn from that urn.

There are about 20 surprisingly common genetic diseases among the Ashkenazi Jews, of which 4 affect sphingolipid metabolism (and, incidentally, promote the growth of neural connections). We now know, to a pretty good approximation, how many human genes there are, and how many of those genes affect sphingolipid metabolism. Using a strategy that is an extended version of the simple hypergeometric model (also applying Bonferroni corrections for multiple comparisons, among other complications) you can get an estimate of the probability of such a cluster of mutations occurring by chance. It's something less than 1 in 100,000. To do this, we used the Gene Ontology database (GO-EBI,EMBL-EBI, 2003), an established tool used to assess the statistical significance of human gene clusters obtained by high-throughput methods such as microarrays.


Rudyard Kipling wrote the Just-So Stories, which explain how the leopard got his spots and so on. He was not ion fact responsible for our current understanding of the hypergeometric distribution: that was a joke.

In my opinion, a careful look at the psychometric data, medieval history, and the biochemical effects of the sphingolipid mutations, combined with Gene Ontology calculations of cluster likelihood, combined with millions of simulations of the population genetics of a surprisingly frequency recessive lethal like Tay-Sachs ultimately produces something more than a Just-So Story.

Posted by: gcochran at Jan 22, 2009 3:29:54 PM"

http://www.marginalrevolution.com/marginalrevolution/2009/01/the-10000-year-explosion/comments/page/2/#comments

Anonymous said...

"I find it interesting that the gap between the black and white adopted children was virtually identical (within just 4-6 points) to the gap between whites and blacks in the general population"

Huh? I've seen data where the black kids score higher than 100. That's > 15 pts over the black mean.

http://books.google.com/books?id=UW9cjBo_nCIC&pg=PA109&lpg=PA109&dq=black+children+adopted+by+white+families+IQ&source=web&ots=rMwbOMHpdO&sig=6GYM7BJDS62jWqN3t2x88mTi7pA&hl=en&sa=X&oi=book_result&resnum=2&ct=result

It depends how old the kids are. The older they are the lower the score. Once they "discover" their blackness it's "lights out" upstairs.

The greater fitness of Tay-Sachs Gauchers etc. heterozygotes is interesting but the uniquely studious Ashkenazi culture has to be subtracted for a definitive conclusion regarding the role of genes in Jewish achievement.

Won't someone take the Boer bate?

Ben said...

"It depends how old the kids are. The older they are the lower the score. Once they "discover" their blackness it's "lights out" upstairs."

As I pointed out above, heritability of IQ rises with age.

Ben said...

In relation to the increase in heritability with age, see page 253of June 2005 issue of Psychology, Public Policy, and Law, Vol. 11, No. 2:

http://psychology.uwo.ca/faculty/rushtonpdfs/PPPL1.pdf

Anonymous said...

As you pointed out before???

I didn't miss it. But it is irrelavent.

What does it mean exactly? That the difference in IQ scores of identical twns decreases with age? Of course it does. IQ tests are less reliable the younger the testee, and children mature at different rates.

But it doesn't mean that if a cohort uniformly scores higher than its parents IQ would predict it will score lower later.

Ben said...

"What does it mean exactly? That the difference in IQ scores of identical twns decreases with age? Of course it does. IQ tests are less reliable the younger the testee, and children mature at different rates."

I think it refers to the extent that differences between people can be attributed to genetics rather than differences in environment.

In terms of identical twins, I think they find that those raised apart still have closer IQ scores than fraternal twins raised together. Obviously suggesting that IQ is significantly hereditable (along with most behavioural traits - see Steven Pinker's recent article in NY Times).

So I think explanations for fade out, like discovering "their blackness" or other culture theories aren't that persuasive.

"But it doesn't mean that if a cohort uniformly scores higher than its parents IQ would predict it will score lower later.

Well, there is also the tendency for regression to the mean. If the parents are both under 100, then the kid's score will probably be between the parent's average score and 100. If the parents are both 150 then the kid will be somewhere between that & 100 (that's what I remember the Bell Curve saying anyway).

Anonymous said...

"So I think explanations for fade out, like discovering "their blackness" or other culture theories aren't that persuasive."

Heritability is not one fixed number (it depends on the variance of environments) and high heritability for IQ does not mean group differences are genetic. This is very counterintuitive.

A redwood planted in the Mojave desert can only be compared to redwoods plated in the Mojave. It cannot be compared to redwoods in Redwood National Park.

Adopted black kids score higher than the white mean and more than 15 points higher than blacks "in the wild". How can that be unless black families are like the Mojave and white adoptive families like Redwood National Park?

Anonymous said...

Fifty years ago the Boer British South African IQ difference was 2/3 SD mostly in the performance section. Now it is near zero.

Ben said...

"Adopted black kids score higher than the white mean and more than 15 points higher than blacks "in the wild". How can that be unless black families are like the Mojave and white adoptive families like Redwood National Park?"

Interesting. Do you have any links or references for that though? I'm just asking because the study cited on Gene Expression suggests scores tended to be similar to the biological parents.

"One longitudinal study, the only one of its kind, of black children raised in white homes, showed that by highschool these adoptees scored no differently on IQ tests than African-Americans raised by their biological parents. Meanwhile three studies of Asians [1] raised in white families showed higher than average test scores. A problem with these latter three papers of Asian adoptees is that they didn't use control samples of white adoptees. Did the Asian children just score higher because adoptees in general score higher?"

http://www.gnxp.com/MT2/archives/004064.html

Ben said...

"Fifty years ago the Boer British South African IQ difference was 2/3 SD mostly in the performance section. Now it is near zero."

How do they explain the closing of the gap? Could that be explained by living in a less cognitively (in terms of what IQ tests measure) demanding rural environment? Nutrition?

Another point is that there wouldn't be that much genetic difference between the Boers (largely Dutch descent?) and the more Anglo South Africans. So if there environment was equalised you'd expect them to be similar in IQ.

I'm not sure if there is much evidence that gaps between whites & East Asians, and Ashkenazi Jews & Africans are showing signs of closing?

Anonymous said...

Link on blacks adopted by upper middle class whites.

http://books.google.com/books?id=UW9cjBo_nCIC&pg=PA109&lpg=PA109&dq=black+children+adopted+by+white+families+IQ&source=web&ots=rMwbOOHr7N&sig=9b3r21XEJ9sSKi1c-1VZT38xumo&hl=en&sa=X&oi=book_result&resnum=2&ct=result

Link on Boer British SA difference:

http://books.google.com/books?id=PSRaJFu8c-YC&pg=PA551&lpg=PA551&dq=Afrikaans+speakers+IQ&source=web&ots=SjWHMGWtU_&sig=0BFceltjfk2ckp5J140UvpmfQMg&hl=en&sa=X&oi=book_result&resnum=1&ct=result

The adopted children still had lower IQs than their adoptive parents and their biological children, but the study is an indication of how profound the black white environmental difference can be.

"by highschool these adoptees scored no differently on IQ tests than African-Americans raised by their biological parents."

The qualification "by high school" is right. Before high school this isn't true.

I haven't read the whole article on the SA question, but whatever the explanation the biological one would be absurd. The European Dutch score higher on IQ tests than the British. The SA Dutch score lower and the white SA underclass is exclusively Africaner. It is another example of how profound environment and culture can be.

Anonymous said...

I forgot. On the Afrikaner link scroll up to page 534 for the beginning of the section.

BTW, the slower reaction time and smaller heads of blacks is sufficient for me to be convinced that part of the difference is genetic. The larger heads of Orientals is also sufficient proof that genes are part of the IQ difference. But I'd hire a black lawyer over an Oriental. Oriental representation in the high verbal IQ field is almost nil.

Anonymous said...

Pre WW II study (1928) where Jews score lower than (what was then the ruling class) N Europeans.

http://psycnet.apa.org/index.cfm?fa=main.doiLanding&uid=1929-00499-001

Bob said...

Some comments relating to the prior messages...

Black children adopted by white families mature to have IQs that are consistent with their biological peers and are not higher, due to their rearing; Asian children adopted by white families mature to have IQs that are consistent with their biological peers and which are higher than their adoptive parents. "Discovering blackness" is not an explanation to any IQ measurement. All breeding groups show the same age related measurements. The B-W gap can be measured at age 2-1/2, so blacks must discover their blackness while very young. [see Rushton, J.P. and Jensen, A.R. (2005). Thirty Years of Research on Race Differences in Cognitive Ability. Psychology, Public Policy, and Law, Vol. 11, No. 2, 235-294.] [also see Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger.]

US blacks have a well known mean IQ that reflects their 25% admixture of European genes; European blacks have the same mean IQ as US blacks. Blacks in sub-Saharan Africa have a mean IQ of 67. In that region, the economy is dominated by Indians who were brought in during Colonial times as workers. Indians built most of the buildings that stand in East Africa. In Brazil, blacks have a mean IQ of 71; mulattos have a mean of 81. The highest mean income in Brazil is by Japanese, followed by Europeans, Mulattos, and Blacks. IQs by nation are reported in Lynn, Richard (2006). Race Differences in Intelligence: An Evolutionary Analysis. Social standing by race is reported in The Global Bell Curve (2008) by Lynn.

I spoke to Gregory Cochran very briefly in 2005, after he delivered a paper titled The Evolutionary Biology of Human IQ Diversity. The material he covered was basically the same as he and Harpending have reported in sources that have been mentioned here. He noted that the chance of a neutral gene appearing as a high frequency is 1 in 20,000 and the chance of an advantageous gene appearing as a high frequency is 400 times greater. The necessary "advantage" to reach this higher probability is just a 1% increase in survival to reproduction. He gave a mutation rate of 10^-9 per year.

The assertion that IQ tests are "less reliable the younger the testee" is not consistent with the literature, at least down to age 6-7. Below that age, testing (Fagan's method) is still highly predictive of mature IQ and academic achievement. The WISC-R is designed for testing ages 1-16 and has a full scale IQ reliability of .95. No adult test has a higher reliability coefficient.

Anonymous said...

"The B-W gap can be measured at age 2-1/2, so blacks must discover their blackness while very young."

But not if adopted by whites.

"Asian children adopted by white families mature to have IQs that are consistent with their biological peers and which are higher than their adoptive parents."

Irrelavent.

"Thirty Years of Research on Race Differences in Cognitive Ability."

I read this. Only a small section has any relevance to the black white difference. The adoption section. And the Minnesota study authors come to the opposite conclusion of Rushton and Jensen. Namely, that environment is dominate in the black white difference.

"Blacks in sub-Saharan Africa have a mean IQ of 67."

Have you met a Sub-Saharan African? Have you met a wheelchair bound, drooling, idiot?

If you really believe that this is a valid measure of these people, you're retarded.

"The assertion that IQ tests are "less reliable the younger the testee" is not consistent with the literature, at least down to age 6-7."

It's apparent you don't know what is meant by test-retest reliability. Validity and reliabilty are two different things.

The WISC does not have a reliablity of .95. The WAIS may starting at age 17.

If Cochran spoke to you, he has no credibility. And it's obvious he knows nothing about Judaism. Niether does Pinker, even though he's a Jew.

Anonymous said...

You might have seen that the WISC has a reliability of .95 when administerd six months apart. That is believable. But a score at age 7and one at 16 will in general differ by much more than a score at 20 and a score at 29.

Bob said...

From Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger:

Sandra Scarr, after conducting the Minnesota Transracial Adoption Study: "Within the range of 'humane environments,'variations in family socioeconomic characteristics and in child-rearing practices have little or no effect on IQ measured in adolescence." P. 476

"There is simply no good evidence that social environmental factors have a large effect on IQ, particularly in adolescence and beyond, except in cases of extreme environmental deprivation." P. 476

By adulthood, all of the IQ correlation between biologically related persons is genetic. P. 178 Phenotypic g closely reflects the genetic g, but bears hardly any resemblance to the (shared) environmental g. P. 187

Anonymous said...

"Sandra Scarr, after conducting the Minnesota Transracial Adoption Study: "Within the range of 'humane environments,'variations in family socioeconomic characteristics and in child-rearing practices have little or no effect on IQ measured in adolescence." P. 476

What is meant by "humane environments"? What is meant by "adolescent"? Scarr came to the opposite conclusion for pre-adolescents.

http://books.google.com/books?id=UW9cjBo_nCIC&pg=PA109&lpg=PA109&dq=black+children+adopted+by+white+families+IQ&source=web&ots=rMwbPKAs8J&sig=1TGwYSJ6MV5jEcVcuLrKraw1LVc&hl=en&sa=X&oi=book_result&resnum=2&ct=result#PPA132,M1

So apparently Jensen is saying that if you grow up in a great environment your adult IQ will be less than you childhood IQ? Or is that true only if you're black? Does that sound credible to you?

"There is simply no good evidence that social environmental factors have a large effect on IQ, particularly in adolescence and beyond, except in cases of extreme environmental deprivation." P. 476

Then what is the environmental cause of the variance in the IQs of identical twins with correction for attenuation?

"By adulthood, all of the IQ correlation between biologically related persons is genetic. P. 178"

And the correlation for siblings is a trivial .4.

Jensen would have you believe that human beings are like weeds and will grow to a gentically predeterimined height wherever their seed lands.

Anonymous said...

When is someone going to take the Boer bait?

Ben said...

"Jensen would have you believe that human beings are like weeds and will grow to a gentically predeterimined height wherever their seed lands."

He's never said that differences are 100% hereditable.

STS said...

Hey Steve,

Why don't we leave the psychometric stuff aside for a moment and think about U.S. technology strategy for a bit.

Here's some fodder for a post and some conversation: Silicon Valley Wants to Stay on the Road to Prosperity.

TH said...

In the Minnesota Transracial Adoption Study, black kids had an average IQ of 97 at age 7 and 89 at age 17. In the same study, the average IQ of white adoptees dropped from 112 at age 7 to 106 at age 17. If the regression of the black adoptees was caused by their "discovering their blackness", what was it that the white adoptees discovered that caused them to lose points?

Anonymous said...

Noone lost points. There were two different tests. Did you get this from wikipedia? The info there contradicts the info here, which was written by Scarr.

http://books.google.com/books?id=UW9cjBo_nCIC&pg=PA109&lpg=PA109&dq=black+children

Ben said...

A pdf from Steve Farron discussing the twin studies.

http://www.affirmativeactionhoax.com/pdfs/Genetic%20Determinism.pdf

Ben said...

And critiques of Mismeasure of Man & Goleman's 'Emotional Intelligence'.

http://www.affirmativeactionhoax.com/pdfs/Goleman.pdf

http://www.affirmativeactionhoax.com/pdfs/Gould.pdf

Steve Sailer said...

According to Flynn, massive IQ increases are not seen in all types of cognitive functioning, just in a couple of areas, which explains why kids these days don't seem all that much smarter, except at programming their new gadgets. The Wechsler Intelligence Scale for Children (WISC) is one of the most popular IQ tests. Here are its ten subtests, ranked in order from smallest to largest IQ gain over 55 years:

WISC Subtest
IQ Gains in Points, 1947-2002

Sample Question

Information 2
On what continent is Argentina?

Arithmetic 2
If a toy costs $6, how much do 7 cost?

Vocabulary 4
What does "debilitating" mean?

Comprehension 11
Why are streets usually numbered in order?

Picture Completion 12
Indicate the missing part from an incomplete picture.

Block Design 16
Use blocks to replicate a two-color design.

Object Assembly 17
Assemble puzzles depicting common objects.

Coding 18
Using a key, match symbols with shapes or numbers.

Picture Arrangement 22
Reorder a set of scrambled picture cards to tell a story.

Similarities 24
In what way are "dogs" and "rabbits" alike?

We see only small changes in the first three mental skills: general knowledge, arithmetic, and vocabulary. And yet these are the skills that come up most in our casual conversation

However, there have been substantial improvements in the next six subtests, most of which involve visual logic. The proliferation of visual imagery was one of the major changes in the social environment in the 20th Century. People have much more practice at decoding images quickly than in the past.

For example, consider how the television remote control and cable television led to channel surfing.

Before, you'd flick the On/Off knob on your TV, sit down while it warmed up, and spend about five minutes watching whatever came on while you slowly decided whether it was worth getting off your couch to turn to another channel—of which there were only a few. In the 1970s, however, viewers with remotes and cable started to rapidly shuffle through dozens of channels. They developed the ability to figure out quickly what was going on and whether they wanted to linger for more than a few seconds.

Finally, the fastest rising subtest on the WISC, Similarities, rewards abstract scientific thinking, what Flynn calls viewing the world through "scientific spectacles."

A child gets a maximum score for replying that dogs and rabbits are "mammals." A kid in 1947 who had never seen a nature documentary on TV would likely have said "They have four legs" or something else more concrete than the Linnaean category "mammals."

Flynn's WISC table points out that the surprising success of IQ tests—they are now 102 years old and appear to be as valid as they ever were since they matured between World War I and World War II—stems from the inventors of IQ testing anticipating which way the world would move.

Flynn told me in an email last week: "I often say to audiences that right from the start the framers of IQ tests themselves looked at the world through scientific spectacles and therefore anticipated the spread of such through the general population."

I also suspect that standardized tests have remained useful predictors of competence in part because the world, in going electronic, has gotten more standardized. Programming your cell phone is a rather like answering questions on the Raven's Progressive Matrices IQ test: it's purely logical and there's only one way to do it.

http://www.vdare.com/sailer/070903_flynn.htm

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