Friday, December 21, 2012

IQ tests are 'meaningless and too simplistic' claim researchers

This appears to have been based on an internet survey and such surveys  are notorious for giving non-representative results.  A large sample size is no substitute for representativeness

The underlying controversy, however, is as old as the hills:  Should IQ be measured as a set of subscores or as one overall score?  Among psychometricians it is known as the Spearman/Thurstone controversy and dates back to the beginning of the last century.

The accepted answer is to present results both ways:  As one overall score plus a set of sub-scores.  Results can reasonably be represented both ways because the subscores are correlated.  Knowing a person's subscore on (say) verbal ability will give you a useful (but not of course perfect) prediction of his mathematical ability.  That has repeatedly been demonstrated.

The novelty in the report below is that the various sub-abilities were said to be NOT correlated  -- which runs contrary to 100 years of findings by others.  I note however that the authors are more cautious in the underlying journal article.  They say:  

Using simulations based on neuroimaging data, we show that the higher-order factor “g” is accounted for by cognitive tasks corecruiting multiple networks. Finally, we confirm the independence of these components of intelligence by dissociating them using questionnaire variables. We propose that intelligence is an emergent property of anatomically distinct cognitive systems, each of which has its own capacity.

That sounds to me as if they admit the existence of a general factor but find that the subfactors don't all use exactly  the same parts of the brain -- which should be no surprise to anyone. 

There is also a question about how comprehensive were the test items used.  Without seeing all the questions, I get the impression  that a deliberate attempt was made to find questions that would not produce correlated results.  One can ask plenty of questions not conceptually related to intelligence and in that case intercorrelations are not be be expected.  In psychometrican's terms, the test would lack construct validity.

The journal article is "Fractionating Human Intelligence" by Hampshire et al.  I look forward to seeing a more detailed examination of the article by those who specialize in IQ studies

After conducting the largest ever study of intelligence, researchers have found that far from indicating how clever you are, IQ testing is actually rather ‘meaningless’.

In a bid to investigate the value of IQ, scientists asked more than 100,000 participants to complete 12 tests that required planning, reasoning, memory and attention.  They also filled in a survey on their background.

They discovered that far from being down to one single factor, what is commonly regarded as intelligence is influenced by three different elements - short-term memory, reasoning, and verbal ability.  But being good at one of these factors does not mean you are going to be equally gifted at the other two.

Scientists from Canada’s Western University in Ontario, also scanned some of the participants’ brains while they undertook the tests.

They found that different parts of the brain were activated when they were tested on each of the three factors.

Traditional IQ tests are ‘too simplistic’, according to the research, which found that what makes someone intelligent is too complex to boil down to a single exam.

IQ, which stands for Intelligence Quotient, is an attempt to measure how smart an individual is.  The average IQ is 100. Mensa, the high IQ society, only accepts individuals who score more than 148, putting them in the top two per cent of the population.

The new study, published in the journal Neuron, suggests that intelligence is too complex to be represented by a single number.

Study leader Dr Adrian Owen, a British neuroscientists based at Western University in Canada, said an ‘astonishing’ number of people had contributed to the research.

‘We expected a few hundred responses, but thousands and thousands of people took part, including people of all ages, cultures and creeds and from every corner of the world,’ he said.

‘When you take 100,000 people and tested their brain function, we couldn’t find any evidence for a single uniform concept of intelligence.

‘The best we could manage is get it down to three elements that contribute to intelligence. But they are completely different factors, unrelated to one another, and you could be brilliant at one and awful at another.  For example, the absent-minded professor.

‘IQ tests are pretty meaningless - if you are not good at them, all it proves is that you are not good at IQ tests.

'It does not say anything about your general intelligence.’ The majority of IQ tests were developed in the 50s and 60s when the way we thought and interacted with the world was different, said Dr Owen.


Wednesday, November 28, 2012

Jensen and Flynn

Thomas Sowell

Anyone who has followed the decades-long controversies over the role of genes in IQ scores will recognize the names of the two leading advocates of opposite conclusions on that subject-- Professor Arthur R. Jensen of the University of California at Berkeley and Professor James R. Flynn, an American expatriate at the University of Otago in New Zealand.

What is so unusual in the academic world of today is that Professor Flynn's latest book, "Are We Getting Smarter?" is dedicated to Arthur Jensen, whose integrity he praises, even as he opposes his conclusions. That is what scholarship and science are supposed to be like, but so seldom are.

Professor Jensen, who died recently, is best known for reopening the age-old controversy about heredity versus environment with his 1969 article titled, "How Much Can We Boost IQ and Scholastic Achievement?"

His answer-- long since lost in the storms of controversy that followed-- was that scholastic achievement could be much improved by different teaching methods, but that these different teaching methods were not likely to change I.Q. scores much.

Jensen argued for educational reforms, saying that "scholastic performance-- the acquisition of the basic skills-- can be boosted much more, at least in the early years, than can the IQ" and that, among "the disadvantaged," there are "high school students who have failed to learn basic skills which they could easily have learned many years earlier" if taught in different ways.

But, regardless of what Arthur Jensen actually said, too many in the media, and even in academia, heard what they wanted to hear. He was lumped in with earlier writers who had promoted racial inferiority doctrines that depicted some races as being unable to rise above the level of "hewers of wood and drawers of water."

These earlier writers from the Progressive era were saying, in effect, that there was a ceiling to the mental potential of some races, while Jensen argued that there was no ceiling but, by his reading of the evidence, a difference in average IQ, influenced by genes.

When I first read Arthur Jensen's landmark article, back in 1969, I was struck by his careful and painstaking analysis of a wide range of complex data. It impressed me but did not convince me. What it did was cause me to dig up more data on my own.

A few years later, I headed a research project that, among other things, collected tens of thousands of past and present IQ scores from a wide range of racial and ethnic groups at schools across the United States. Despite serious limitations in these data, due to constraints of time and circumstances, these data nevertheless threw some additional light on the subject.

A feature article of mine in the Sunday New York Times Magazine of March 27, 1977 pointed out that any number of white groups, here and overseas, had at some point in time had IQs similar to, and in some cases lower than, the IQs of black Americans. During the First World War, for example, white soldiers from some Southern states scored lower on army mental tests than black soldiers from some Northern states.

Professor Jensen read this article and came over to Stanford University to meet with me and discuss the data. That is what a scholar should do when challenged. But the opposite approach was shown by Professor Kenneth B. Clark, who earlier had sought to dissuade me from doing IQ research. He said it would "dignify" Jensen's work, which Clark wanted ignored or discredited instead.

Unfortunately, Professor Clark's ideological approach became far more common in academia, so much so that Jensen's attempts to speak on campuses around the country provoked dangerous disruptions, instead of reasoned arguments.

Years later, Professor James R. Flynn created the biggest challenge to the hereditary theory of intelligence, when he showed that whole nations had risen to much higher results on IQ tests in just one or two generations. Genes don't change that fast.

Professor Flynn told me that he would never have done his research, except that it was provoked by Jensen's research. That is just one of the reasons for having a free marketplace of ideas, instead of turning academic campuses into fortresses of politically correct intolerance.


Sowell's comments are those of an unusually decent man but his argument is unpersuasive.  You can to this day find some whites who are dumber than some blacks but it is the groups OVERALL (and preferably across time) that are of greatest interest and the overall black/white gap has been consistent as far back as it has been measured.  But there are exceptions to every rule and some blacks are very bright.  Sowell is one of them.

Friday, November 2, 2012

High IQ as just one part of biological good functioning

I have for some years been putting forward evidence in favor of the view that high IQ is just one aspect of general biological good functioning.  I never thought to get the NYT on my side but you can read it below

FEW of us are as smart as we'd like to be. You're sharper than Jim (maybe) but dull next to Jane. Human intelligence varies - and this matters because smarter people generally earn more money, enjoy better health, raise smarter children, feel happier and, just to rub it in, live longer as well.

But where does intelligence come from? How is it built? Researchers have tried hard to find the answer in our genes. With the rise of inexpensive genome sequencing, they've analysed the genomes of thousands of people, looking for gene variants that clearly affect intelligence, and have found a grand total of two.

One determines the risk of Alzheimer's disease and affects IQ only late in life; the other seems to build a bigger brain, but on average it raises IQ by all of 1.29 points.

Other genetic factors may be at work. A report last year concluded that several hundred gene variants taken together seemed to account for 40 per cent to 50 per cent of the differences in intelligence among the 3500 subjects in the study.

But the authors couldn't tell which of these genes created any significant effect. When they tried to use the genes to predict differences in intelligence, they could account for only 1 per cent of the differences in IQ.

"If it's this hard to find an effect of just 1 per cent," Robert Plomin, a professor of behavioural genetics at King's College London, told New Scientist, "what you're really showing is that the cup is 99 per cent empty."

But is the genetic cup really empty, or are we just looking for the wrong stuff?

A developmental neurogeneticist Kevin Mitchell at Trinity College Dublin, thinks the latter. In an essay he published in July on his blog, Wiring the Brain, Mitchell proposed that instead of thinking about the genetics of intelligence, we should be trying to parse "the genetics of stupidity," as his title put it. We should look not for genetic dynamics that build intelligence, but for those that erode it.

The premise for this argument is that once natural selection generated the set of genes that build our big, smart human brains, those genes became "fixed" in the human population; virtually everyone receives the same set and precious few variants affect intelligence. This could account for the researchers' failure to find many variants of measurable effect.

But in some other genetic realms we do differ widely, for example, mutational load - the number of mutations we carry. This tends to run in families, which means some of us generate and retain more mutations than others do. Among our 23,000 genes, you may carry 500 mutations while I carry 1000.

Most mutations have no effect. But those that do are more likely to bring harm than good, Mitchell says , because "there are simply many more ways of screwing something up than of improving it".

Open the hood of a smooth-running car and randomly turn a few screws, and you'll almost certainly make the engine run worse than before. Likewise, mutations that change the brain's normal development or operation will probably slow it down. Smart Jane may be less a custom-built, high-performance model than a standard version pulling a smaller mutational load.

We also inherit - through genes yet to be identified, of course - a trait known as developmental stability. This is essentially the accuracy with which the genetic blueprint is built.

Developmental stability keeps the project on track. It reveals itself most obviously in physical symmetry. The two sides of our bodies and brains are constructed separately but from the same blueprint of 23,000 genes. If you have high developmental stability, you'll turn out highly symmetrical. Your feet will be the same shoe size, and the two sides of your face will be identical.

If you're less developmentally stable, you'll have feet up to a half size different and a face that's like two faces fused together. Doubt me? Take a digital image of your face and split it down the middle. Then make a mirror image copy of each half and attach it to its original. In the two faces you've just made - one your mirrored left side, the other your right - you'll behold your own developmental stability, or lack thereof.

Both those faces might be better looking than you are, for we generally find symmetrical faces more attractive. It also happens that symmetry and intelligence tend to run together, because both run with developmental stability. We may find symmetrical faces attractive because they imply the steadiness of genetic development, which creates valuable assets for choosing a mate, like better general fitness and, of course, intelligence - or as Mitchell might put it, a relative lack of stupidity.

These ideas don't strike geneticists as radical or contrary. A geneticist at Princeton University Leonid Kruglyak, who studies yeast and flatworms, noted that geneticists had long recognised that mutations could "throw sand in the gears of the brain" and that complex traits arose in complicated ways.

"Talking about 'a gene for a trait' is a shorthand at best," he wrote, "and a well-known fallacy at worst."

Mitchell agreed. "This isn't a brand new idea," he says. "But it's not one that has been generally adhered to in intelligence studies."

Not brand new, perhaps, but it's this kind of "inversion of thought" that can spark new approaches to intractable problems.

Dr Jay Giedd, who studies brain development at the US National Institutes of Health, has done research suggesting that the brain blooms through many small arcs of development that make it responsive to experience - and vulnerable to error. At first, he says, he was sceptical of Mitchell's idea. Then he discussed it with colleagues at a neuroscience meeting.

"My initial thought was that it would be easy to sink the argument," Giedd says. But the more they discussed it, the more sense it made. "Everybody I ran it by seemed to feel the logic is sound."


Sunday, October 7, 2012

IQ linked to levels of happiness

This is to be expected when we realize that IQ is a measure of GENERAL problem solving ability.  High IQ helps with just about everything.  More speculatively, it is consistent with high IQ being one aspect of general biological good functioning

People with lower intelligence are more likely to be unhappy than their brighter colleagues, according to UK researchers.

Their study of 6,870 people showed low intelligence was often linked with lower income and poor mental health, which contributed to unhappiness.

The researchers are calling for more help and support to be targeted at people with lower IQs.

Their findings were published in the journal Psychological Medicine.

The researchers, at University College London, analysed data from the Adult Psychiatric Morbidity Survey in England.

One of the questions was: "Taking all things together, how would you say you were these days - very happy, fairly happy or not too happy?" People's verbal IQ was also assessed.

The highest proportion saying they were "very happy" was found in people with an IQ between 120 and 129 - 43% said they were very happy.

However, the highest proportion saying "not too happy" - 12% - was found in people with an IQ between 70 and 79.

Dr Angela Hassiotis said: "People in the lower end of the normal spectrum are more likely to consider themselves not happy."

The study said lower intelligence was linked to lower income, worse health and needing help with daily life, such as shopping or housework - all of which contributed to unhappiness.

Dr Jonathan Campion, a consultant psychiatrist and director of public mental health at the South London and Maudsley NHS Foundation Trust, said: "The study suggests that higher IQ appears to be associated with improved wellbeing, but that this relationship between IQ and wellbeing is partly due to higher IQ being linked with better income, health and less mental illness."


Tuesday, August 14, 2012

Some more observations about Ron Unz and IQ

There is an ongoing "debate" between  Richard Lynn and Ron Unz regarding international variations in IQ.  Although he is the publisher of "The American Conservative", Unz takes the classic Leftist view that  low IQ is caused by  poverty, although he does make the concession that "some residual European IQ differences might indeed be due to genetics rather than environment".  

Poverty is the cause of everything according to Leftists.  They even blamed the 9/11 events on poverty until it finally penetrated their unseeing eyes that Bin Laden was in fact a billionaire.

Unz's article is replete with accusations that Lynn has acted in bad faith  (though not in those  words), which seems to me rather deplorable, though I was not too surprised by it.  When Unz replied to my observations about crime and  immigration, his comments were almost hilariously "ad hominem":  He suggested that I was disqualified from commenting on such matters because I live in Australia!

Perhaps I can be rather Old Testament in the matter however by in turn accusing Unz of bad faith.  In his desire to discredit Lynn's  hypothesis of substantial genetic influence on IQ he cherrypicks his data heavily, as Sanders has pointed out at length.  And it also seems to me that he rushes by the German data in great haste.  I would think that the differences between the old East and West Germany should be a very good test of Unz's "poverty" hypothesis. After  several generations of real poverty, East Germans were found to have average IQs that were about the same as West Germans -- even though West Germany was one of the world's most prosperous countries, one which made a "miraculous" economic recovery from WWII  (the famous Wirtschaftswunder).

If poverty had no effect there, whence Unz's claim that poverty explains almost all IQ variation?  Unz does not allude to the German results in his latest article but here is what he said in his earlier article:
Consider, for example, the results from Germany obtained prior to its 1991 reunification. Lynn and Vanhanen present four separate IQ studies from the former West Germany, all quite sizable, which indicate mean IQs in the range 99–107, with the oldest 1970 sample providing the low end of that range. Meanwhile, a 1967 sample of East German children produced a score of just 90, while two later East German studies in 1978 and 1984 came in at 97–99, much closer to the West German numbers.

These results seem anomalous from the perspective of strong genetic determinism for IQ. To a very good approximation, East Germans and West Germans are genetically indistinguishable, and an IQ gap as wide as 17 points between the two groups seems inexplicable, while the recorded rise in East German scores of 7–9 points in just half a generation seems even more difficult to explain.

Unz here cherrypicks again by seizing on the widest possible gap in the data rather than on the reasonably inferrable average.  The 107 result is clearly an outlier and a West German mean of around 100 seems the best attested. And the convergence between the two later East German studies  suggest that the 1967 East German finding was also an outlier.  So we are left with an East German mean that is essentially undistinguishable from the West German  mean.

Will Unz be defeated by that fact?  Perhaps not. He leaves himself an "out" by saying "but East Germans hardly suffered from severe dietary deficiencies".  So now it is not poverty that affects IQ but rather "severe dietary deficiencies".  The goalposts have moved!

I don't know that it is really worth saying much more about Unz's merry journey through the data but I will briefly mention two other points:  Unz consistently discounts the immigrant effect, the claim that immigrants are in various ways a superior subset of their parent population.  Yet the USA seems a clear proof that such an effect exists.  Herrnstein & Murray long ago showed that lower IQ goes with lower social class and the mass of immigrants to both Australia and America in the past were clearly from the lower strata of their host societies. To this day, upper class English accents are as rare in Australia as British regional accents are common.  So average white IQs in both Australia and America should be lower than the average IQ in (say) Britain -- right? 

But it isn't so.  The average IQ in all three countries is essentially the same.  The most readily apparent explanation for that convergence would seem to be the immigrant effect:  The immigrants were a superior subset of the population from which they originated.  And the way America has in various ways led and dominated the world at least since WWII would also seem to suggest that those immigrant genes were pretty good.

A final point in defence of Lynn.  Unz says:  "Finally, Lynn closes his rebuttal by repeating his boilerplate disclaimer that he has “never maintained that IQ is overwhelmingly determined by genetics,” although this seems to be his clear reasoning in every single particular example he discusses"

I suspect here that Unz is failing to see that Lynn has had two aims in his work:  His main aim is to show that IQ is economically important and ascribing any origin to the  differences observed is secondary to that aim.  And that refusal to ascribe is what Lynn is doing when he makes modest claims for what he has shown.  In science, however, once one question is answered, new questions arise and Lynn's demonstration of national differences in IQ does quite immediately lead to a question of how those IQ differences arise.  And in rejecting Unz's "poverty" reasoning Lynn has moved on to the derivative question.

And even there, I think  Unz is seeing only what he wants to see in Lynn's words.  Lynn's denial of an "overwhelming" influence is perfectly consistent with around 100 years of IQ research.  The normal finding from twin studies is that IQ is about two thirds genetically determined.  Whether two thirds is "overwhelming", I leave others to judge but I submit that Unz has read more into Lynn's words than is there.

Prominent psychologist Steven Pinker also has some  comments on Unz's dubious logic and in addition  makes some useful points about the massive support for the heritability of IQ etc.  He is far too cautious to endorse Lynn's position, however.  To do so would be academic suicide  -- JR

Monday, August 6, 2012

Ron Unz and IQ

I seem to be a consistent critic of Ron Unz, editor of "The American Conservative". I noted yesterday (and earlier) that his idea of low criminality among Hispanics is contradicted by Obama's deportation  statistics and I also took a few potshots at his theory that IQ differences between nations are mostly the effect of environmental  factors. 

So I am pleased that Richard Lynn has now given a systematic reply to Unz on the IQ question.  Lynn echoes some of the points I made (and I did get an email from Lynn saying he liked my article) but his reply is far more detailed and scholarly and, I think, a good reply  to Unz's claims.

Unz has replied to Lynn and it looks to me that the two sides are converging, with the differences being in matters of degree. Both parties agree that the environment has some influence but Lynn makes a strong case for the importance  of genetics.


Could a brain scan tell you how smart you are? Research shows intelligence linked to strength of neural connections

More evidence that IQ is genetically determined.  We are now getting an idea of  the specific mechanisms involved

Research suggests that 10 per cent of individual differences in intelligence can be explained by the strength of neural pathways connecting the left lateral prefrontal cortex to the rest of the brain.

The findings, published in the Journal of Neuroscience, establish 'global brain connectivity' as a new approach for understanding how human intelligence relates to physiology.

'Our research shows that connectivity with a particular part of the prefrontal cortex can predict how intelligent someone is,' said Michael Cole, PhD, a postdoctoral research fellow in cognitive neuroscience at Washington University and lead author of the study.

He says the research is the first to provide compelling evidence that neural connections between the lateral prefrontal cortex and the rest of the brain make a unique and powerful contribution to the cognitive processing underlying human intelligence.

'This study suggests that part of what it means to be intelligent is having a lateral prefrontal cortex that does its job well; and part of what that means is that it can effectively communicate with the rest of the brain,' added study co-author Todd Braver, PhD, professor of psychology in Arts & Sciences and of neuroscience and radiology in the School of Medicine.

One possible explanation of the findings, the research team suggests, is that the lateral prefrontal region is a 'flexible hub' that uses its connectivity to monitor and influence other brain regions.

'There is evidence that the lateral prefrontal cortex is the brain region that "remembers" the goals and instructions that help you keep doing what is needed when you're working on a task,' said Prof Cole.  'So it makes sense that having this region communicating effectively with other regions (the "perceivers" and "doers" of the brain) would help you to accomplish tasks intelligently.'

While other regions of the brain make their own special contribution to cognitive processing, it is the lateral prefrontal cortex that helps coordinate these processes and maintain focus on the task at hand. This happens in much the same way that the conductor of a symphony monitors and tweaks the real-time performance of an orchestra.

The findings are based on an analysis of functional magnetic resonance (fMRI) brain images captured as study participants rested passively and also when they were engaged in a series of mentally challenging tasks associated with fluid intelligence, such as indicating whether a currently displayed image was the same as one displayed three images ago.

Previous findings relating lateral prefrontal cortex activity to challenging task performance were supported. Connectivity was then assessed while participants rested, and their performance on additional tests of fluid intelligence and cognitive control collected outside the brain scanner was associated with the estimated connectivity.

Results indicate that levels of global brain connectivity with a part of the left lateral prefrontal cortex serve as a strong predictor of both fluid intelligence and cognitive control abilities.

More  HERE

Friday, July 20, 2012

Is the female of the species really more intelligent than the male?

New research into IQ levels could end the modern taboo on comparing cleverness, says Michael Hanlon

We accept that some people are taller than others, or darker- or lighter-skinned, or better at running. We also accept that these differences are due, at least in part, to genetics. Yet there is one area where we continue to insist that there cannot be any innate biological distinction between different people, or groups of people, and that is in our minds. The merest suggestion that there may be hard-wired disparities in intelligence causes the most terrible wailing and gnashing of teeth, even though such physical and mental variations – dictated by genes and environment – are exactly what you would expect in an abundant species that has adapted to just about every corner of the globe.

That taboo, however, may be breaking down. In his new book, the brilliant psychologist James Flynn, of Otago University in New Zealand, has revealed that, for the first time, women (in some developed countries) are systematically outperforming men in standardised tests of intelligence. This contradicts earlier findings which suggested that, historically, men have had IQs that were a couple of points higher – or rather, have performed marginally better on a whole slew of intelligence metrics, which measure subtly different things.

The reaction to this finding has been largely positive. Most reports have concentrated on women’s ability to “juggle” and to “multi-task”, with the conclusion: “Didn’t we know this all along?” Expect to hear the old clarion call of “men are redundant”, with the human male reduced to a shambling, knuckle-dragging brute lost in a sea of feminised modernity.

Imagine, however, that Flynn had found the opposite. Suppose that his trawl of standardised measures of intelligence in schoolchildren and young adults, in countries as disparate as Estonia, Argentina, Israel and New Zealand, had confirmed, once and for all, that men had slightly higher IQs. Would that finding be celebrated?

Of course not. Howling columnists would queue up to pour scorn on the very notion, stating that the idea of innate sex differences in IQ is utterly chauvinist. Others would take issue with the whole notion of measured intelligence: “What is IQ,” they would ask, “but a measure of the ability to do intelligence tests?”

Either way, it is important to stress that the differences we are talking about are very small, a percentage point or two at most – and whatever the truth, it’s not as though we can do much about it. The more interesting question is not whether women are cleverer than men, but why this should be so, and why this seems to be a recent trend.

First, we have to dismiss the pernicious but persistent fallacy that IQ is meaningless. The tests used today attempt to measure something called g, a measure of innate general intelligence that is divorced, as far as possible, from cultural and social bias. Thus questions tend to involve not word associations (which are influenced by your level of literacy and knowledge) but connections between patterns and shapes, order and structure.

Most psychologists now accept that while IQ (or g) may not be a measure of pure intelligence per se, it is certainly a measure of something that correlates very well with it. People with high IQs tend to end up with better qualifications, better jobs, higher earnings and longer lives. Crucially, they are also perceived as “cleverer”. Like it or not, being a successful human has a lot to do with being smart – and IQ, or g, does seem to be a fair measure of smartness.

This brings us to one of the most interesting – and scientifically counter-intuitive – findings to have emerged in the last 100 years: namely, that we are all, men and women alike, getting brighter.

The trend was discovered by, and named after, Flynn himself back in the 1980s. In industrialised countries, both adults and children are routinely subjected to various IQ measurements. And, since such testing began in the first half of the 20th century, the average IQ of both sexes has risen by between 10 and 20 per cent. Every few years, the tests had to be revised to make sure that the average score remained at 100 – and in every country, that revision meant making the tests harder.

This means that if a British child scores 100 on an IQ test set in 2012, he would score 110 or so on a test dating from the 1970s. In some countries, such as the Netherlands, where the Flynn Effect was first spotted, the increase has been even more spectacular – a full 30 IQ points between 1950 and 1980. Overall, IQ in both industrialised and developing nations is rising by about three points per decade.

For years, the cause of the Flynn Effect was a mystery. One thing it could not be was genetic: the effect is happening too fast for any form of evolution to be occurring. Better diet was a popular theory, but places like the US, Canada and Scandinavia have been well-fed for a century or more. Education may have been a factor – but again, the increases continued well into the era of compulsory universal schooling in most countries.

In the end, it was Flynn himself who solved the mystery. The effect, he argued, is not due to innate changes in our brains, but to how they react to the sort of problems that define the modern world. Flynn gives an example: “If I were to have asked my father, say, 'What do a dog and a rabbit have in common?’ and then ask the same question today of a bright schoolchild, I would get two answers.” His father, like most “old-fashioned” people (Flynn is in his eighties, so his father was a product of the 19th century) would look for associations. “Dogs hunt rabbits,” he might have said – which is not wrong, but nor is it the answer to the question.

Today, any schoolchild would give the “right” answer, namely: “they are both animals” or “they are both mammals”. Flynn’s point is that until recently, this categorising of the world, putting things into boxes – mammals or not-mammals, dollars or pounds, Apples or PCs – was not the way people thought. In this sense IQ, or rather differences in IQ, may not be so much a measure of intelligence as of modernity.

It is this that may give us a clue as to why women are not only catching up with men but, in some places, starting to overtake them. There may be something innate about the way women’s brains are put together (or the demands placed upon them) that allows them to cope with complexity and the need to systematise. As Prof Flynn said at the weekend: “In the last 100 years the IQ scores of both men and women have risen, but women’s have risen faster. This is a consequence of modernity. The complexity of the modern world is making our brains adapt and raising our IQ.”

Many mysteries remain about human intelligence. Will the Flynn Effect continue, so that our grandchildren look down upon us as barely sentient dullards? Or will it go into reverse, as dysgenic effects (the fact that people with lower IQs tend to have more children) take over? Will the developing world continue to catch up with the old industrialised world? Why do men continue to outperform women in intelligence tests in non-industrialised societies?

Some of this research may be controversial. After all, if talking about sex and IQ is tricky, talking about race and IQ is incendiary: as with high-IQ women, we are generally happy to talk about certain ethnic groups (such as some Jewish populations) having high IQs, but less happy with the corollary, namely that others are less well endowed.

Yet in an increasingly knowledge-driven world, where brains are more important than brawn to a degree never seen before, we need to understand these differences, if for no other reason than to help raise everyone to their potential. Being scared to talk about it is – well, just stupid.


The above article is informative and well-argued and it is pleasing to note that  it appeared in a major British newspaper.  On some matters of detail, however, I have to differ. 

Flynn's argument that we have only recently started to categorize is absurd. Every noun in our  language stands for a category of things.  Categorization is a central human survival strategy.  It enables us to make predictions and thus protect our futures to  some extent.  Even cavemen would have readily detected the difference between a dog and a rabbit, for instance (to use the example above).  Their hunting trips would have had little success otherwise.  Expecting a rabbit to help you bring down prey would be pretty futile.

So  what alternative do I offer to Flynn's explanation? I agree with him that modernity generally is the explanation but I differ on which aspects of modernity are involved.  One aspect is increasing test sophistication.  As education has become more widespread and extended into the late teens, kids have developed strategies for passing tests (guessing when uncertain, for instance) and those strategies help with IQ tests too.  A test of that explanation is that the rise in IQ should now be levelling off as just about everybody now is exposed to a lot of education.  And that does indeed appear to be happening in some countries.  The Flynn effect appears to be fading.  IQ levels seem to be approaching an asymptote, in statisticians' terms.

  But there are other aspects of modernity that are presumably important too -- improved peri-natal care, for instance and also childbirth itself.  Babies can quite easily be brain-damaged to varying degrees during birth and the much increased use of episiotomies and Caesarians would obviate a lot of that.  So more babies are born with their brains functioning to their maximum potential.

So what do I make of the current slightly higher scores of women in some countries?  For a start, it is perfectly easy to design a test that will show either sex as brighter.  Women have better verbal skills and men have better visuo/spatial skills so if you want to show women as brighter you put in more verbal questions and if you want to show men as brighter you put in fewer verbal questions.  So it is possible that recent re-standardizations of tests have added more items in areas that women are good at.

Another possibility is the way the educational system has become anti-male, with female characteristics praised and male characteristics deplored.  This has led to extensive alienation of young males and a much higher educational dropout rate among them.  In such circumstances, then, males get on average less opportinity to acquire that test sophistication I referred to above.  We live in a feminized environment generally, in fact, compared to (say) 100 years ago so there may be many ways in which females are subtly advantaged.

The important point, however, is to recognize that people do differ in many ways and that, like it or not,  IQ is one difference that affects a lot of things that we value.  High IQ, for instance, is associated with greater wealth and better health while low IQ is associated with higher levels of crime and greater poverty.  -- JR

Friday, July 13, 2012

Mexican IQ

The article by Fred Reed below gets a lot of things right but gets a simple thing wrong so I thought it might be useful to put it up for both reasons.  His comments about the characteristics of Mexican and US culture seem spot-on to me and the differences between the two cultures do play a part in explaining why Mexico is in an apparently permanent  mess.

In his comments about IQ, however, Fred seems to forget what an average is.  The Mexican IQ average includes the large, semi-literate rural population and that drags the average down.  So showing that the Mexican middle class performs better than what that average would lead one to expect proves nothing and is essentially irrelevant

And in any case, smart fraction theory says that it is the IQ of the top 5% that matters, not the average IQ.  The most vivid example of that is Israel, which has overall only an average IQ (Due to the large fraction of the population that came from Arab lands).  But Israel also has a very bright sub-population of Ashkenazi origin and it is that sub-population that mostly accounts for Israel's frankly brilliant achievements.

What the average IQ of Mexico's top 5% is I have no idea but Fred is right in saying that cultural factors would hold them back even if they were very bright

The higher up the Mexican social hierarchy you go, the whiter people seem to get so Mexico is, like Israel, still a mixture (not a blend) of two broad sub-populations of different racial origins  (Spanish and native).  So that could well be integral to explaining why the Mexican middle class performs well above what one would expect from the national average.  They have a larger Spanish genetic component

The Mexican authorities are of course aware of the demographic differences  in their population and appear rather nervous about its potential for social combustion.  So they have promulgated the amusing doctrine of "La Raza"  -- the pretence that there is such a thing as a Mexican "race".  I doubt that it fools many Mexicans, though.  Its main use seems to be among Hispanics living in the USA

I belong to a list-serve of exceedingly bright people (I am not one of them) to include Ivy profs, who believe that IQ largely determines human destiny. This is in part I suspect because IQ is something they have, but it is possible that I am being snide in this. They regard as canonical the book IQ and the Wealth of Nations, which purports to show a correlation and by extension a causal relationship between mean national IQ and prosperity. They assert that the mean IQ of Mexico, where I live, is about 86, well below the mean of roughly 100 of white Americans. This, they further assert, accounts for the comparative backwardness of Mexico. Does it?

Now, some brush-clearing. Intelligence obviously exists, in the street sense that we all recognize. Some people obviously have more of it than others. There is obviously a genetic element. No biological reason exists to believe that genetically distinct groups cannot vary in intelligence. IQ, within cultures anyway, provides at least a rough measure of intelligence: It is easy to distinguish people with IQs of 180 from those with IQs of 80. So, in principle, Mexicans could be innately stupid. Are they?

 I would like to think not, but what I want to think doesn’t seem to determine reality. (I regard this as a major design flaw of the universe.) How could I tell whether Mexicans were dull? It seemed to me that the alleged deficit, almost fifteen points, ought to be obvious. In fact I wondered whether a nation with a mean IQ of 86 could run airlines, hospitals, and telephone and internet companies. Which Mexico does.

While I could not test the entire population, I thought a reasonable approach might be to compare the apparent intelligence of Americans and Mexicans in professions of which I knew something. This I did.

A few days ago, I saw a retinologist in Guadalajara. Ophthalmological specialties are not for the fumble-minded, yet he was as intelligent and competent as any I have seen in the US. He also spoke near-perfect English. I tend to ask questions, which gives doctors a chance not to know the answers, or half know them. Not this guy. He was sharp. He sent me to a local retina clinic for optical-coherence tomography and a fluorescein angiogram. I have had these things done in the US, and saw no difference in the competence of those administering them.

Now, the IQist response, reasonable enough as a question, is to argue that even in a country with a mean IQ of 86 there will be a few who can perform at a high levels. True. This is the argument of The Only Fifty Smart Mexicans. The question is how many hundreds of thousands of the Only Fifty you can have before the numbers become embarrassing. After nine years in Mexico, I have seen a lot of dentists and doctors, using all manner of, for example, ultrasound-Doppler  gear, and seen no difference in apparent intelligence.

A small difference would not be detectible by this method. But fifteen points?

Take another field, one that I know well: journalism.  I have read lots of Mexican newspapers (they are on the web). They are as well-written as American. The Spanish in editorial columns is syntactically more complex than American journalistic English. Such journalists as I have met have been very smart. Television journalism is like the American, except that in talking-head shows there is civility and people don’t talk over each other. (And, overall, the content is less controlled, but this is another matter.)

The same happens in daily life. I have no sense that the civilized population is dim-witted. Here things are tricky: A large part of the country has barely risen above peasantry, and seems stupid, as much so as America’s Scotch-Irish louts of the 1800s or inhabitants of Chinese villages today.  Among the approximately middle class—more a psychological than an economic designation—people seem as bright as Americans. I see them in banks, travel agencies, pharmacies. And I encounter way too many kids who have learned fair to good English, many in high school. I mean English English, not Frito bandido dialect.  With a mean IQ of 86?

An IQist asked me a bit challengingly how many kids I knew who could qualify for Harvard. Two. One is my stepdaughter. The other is a guy whose mother owns a local bar. Natalia is in university, he by choice in some nothing job. (The women in Mexico are regularly more impressive than the men.) Obviously kids whom Natalia chooses as friends are not average, but two Ivy intelligences out of the perhaps ten kids I know squares poorly with the IQist theory.

In saying all of this, I am not suggesting that Mexico has achievement the intellectual development of Finland. While it is generally literate, much of it is barely so. Very large chunks of the population live in ignorance and do not produce retinologists. What I do suggest is that far too many people here do technically and otherwise demanding things for the IQ-86 theory to hold water.

When do exceptions cease to be exceptions? Maintaining modern cars with their linguini wiring and computers is not for the stupid. They do it. Ditto, building highways through mountains. They do it. Ditto, walking internet customers through the internals of modems. The Telmex techs regularly do it. Ditto, pirating software with tight security, such as Adobe, or Windows 7 so that it updates. Young techs do it.

So, the IQists ask reasonably, if Mexicans are not stupid, why is the country backward? Where are the Nobelists in physics, the Intels, the Apollo programs? Why no Bill Gates?

There are several becauses. Because the society is profoundly corrupt, with (it sometimes seems) everything and everybody being for sale. Because of a lack of entrepreneurial spirit, a tendency to be content with enough. Because Mexicans tend to live entirely in the present, instead of having one foot in the future as Americans do. Because of a resentful envy of the smart and ambitious (cf. “acting white”) instead of following their example; this is serious. Because envy and distrust of one another make it hard for them to work together. Because of a lack of interest in study. Because so very many of the young marry at sixteen, have a baby, and do nothing thereafter.

If these were just Fred’s opinions, they would be ignorable. It is also the view of Violeta and Natalia. Should anyone want a truly insightful exposition of why Mexico is as it is, read Mañana Forever, by Carlos Casttañeda, a former foreign minister of Mexico. His view, with which I entirely agree, is that Mexico is mostly a modern country creeping into the First World, but crippled by the culture of a century ago. See above.

Am I (and Castañeda) right about this? IQists tend to dismiss the invocation of culture as an evasion—real men believe in IQ—or to argue that defects of culture are the results of low intelligence. This is highly debatable. Consider the following list of founders of major companies in the information technologies (largely from memory, so I hope right):

Google (Sergei Bryn, Larry Page), Intel (Gordon Moore, Robert Noyce), Apple (Steve Jobs, Steve Wozniak), Microsoft (Bill Gates), Dell Computer (Michael Dell), Facebook (Mark Zuckerberg), YouTube (Chad Hurley, Steve Chen, Jawed Karim), Netscape (Mark Andreesen), Yahoo (Jerry Yang, David Filo), AMD (long list of guys from Fairchild Semiconductor), Twitter (Jack Dorsey), Wikipedia (Jimmy Wales, Larry Sanger), (Ron Unz), PayPal (Peter Thiel), Ebay (Pierre Omidyar).

Note that they are overwhelmingly either American or working in America. Why America? Gringos are no smarter than Europeans, Chinese, Japanese, or Koreans. The countries of all of the foregoing countries run huge high-tech companies, but their college kids don’t think, “Geez, I’m bored. I guess I’ll start Dell Computer, or Facebook, or maybe Microsoft. Beats doing a doob.” Certain thoughts seem embedded in American culture: “Why not?” “Who says I can’t?” “Bet me.” “Let’s wing it and see what happens.” It is not Mexico. Or much of anywhere else.


Monday, June 11, 2012

Why Nations Fail

In Why Nations Fail, Acemoglu and Robinson have extended their Inclusive Good/Extractive Bad dichotomy. If anything good ever happened anywhere in world history, it was due to “inclusive institutions” and vice-versa. Sir Karl Popper, the philosopher of science, would have torn his hair out trying to read Why Nations Fail. He would have found Acemogluism as unfalsifiable (and thus as unscientific) as Freudianism and Marxism.

Now, I’m a big fan of inclusive institutions and don’t like exploitative ones. But Acemoglu’s dogma strikes me as a tad superficial. For instance, he focuses on the border cities of Nogales, Arizona, and Sonora. Why is the American side richer? It must be because America has better institutions.

OK…but what makes for better institutions north of the border? After all, Mexico has had plenty of opportunity to study American institutions. Could the enduring differences have something to do with America having a lot of Americans?

What’s the real story behind good and bad institutions? Two brave economists from Africa, Isaac Kalonda-Kanyama of the University of Johannesburg and Oasis Kodila-Tedika of the University of Kinshasa, have tackled this question head-on in a new study entitled Quality of Institutions: Does Intelligence Matter? Their conclusion:

    "We analyze the effect of the average level of intelligence on different measures of the quality of institutions, using a 2006 cross-sectional sample of 113 countries. The results show that average IQ positively affects all the measures of institutional quality considered in our study, namely government efficiency, regulatory quality, rule of law, political stability and voice and accountability. The positive effect of intelligence is robust to controlling for other determinants of institutional quality."

Don’t expect Kalonda-Kanyama and Kodila-Tedika to get big career boosts from their finding.


Thursday, April 19, 2012

Tiny gene change affects brain size, IQ: scientists

One more piece of the jigsaw.  There have now been several genetic changes found to be associated with higher IQ.  The interest of this discovery is that the gene seems to work by increasing brain size.  High IQ people do tend to have bigger brains,  though the effect is not a strong one.  So this finding confirms that the size effect is  genetic

An international team of scientists said Sunday the largest brain study of its kind had found a gene linked to intelligence, a small piece in the puzzle as to why some people are smarter than others.

A variant of this gene “can tilt the scales in favour of a higher intelligence”, study leader Paul Thompson told AFP, stressing though that genetic blessings were not the only factor in brainpower.

Searching for a genetic explanation for brain disease, the scientists stumbled upon a minute variant in a gene called HMGA2 among people who had larger brains and scored higher on standardised IQ tests.

Thompson dubbed it “an intelligence gene” and said it was likely that many more such genes were yet to be discovered.

The variant occurs on HMGA2 where there is just a single change in the permutation of the four “letters” of the genetic code.  DNA, the blueprint for life, comprises four basic chemicals called A (for adenine), C (cytosine), T (thymine) and G (guanine), strung together in different combinations along a double helix.  In this case, the researchers found that people with a double “C” and no “T” in a specific section of the HMGA2 gene had bigger brains on average.

“It is a strange result, you wouldn’t think that something as simple as one small change in the genetic code could explain differences in intelligence worldwide,” said Thompson, a neurologist at the University of California at Los Angeles.

The discovery came in a study of brain scans and DNA samples from more than 20,000 people from North America, Europe and Australia, of European ancestry.

People who received two Cs from their parents, a quarter of the population, scored on average 1.3 points higher than the next group — half of the population with only one C in this section of the gene.

The last quarter of people, with no Cs, scored another 1.3 points lower.   “The effect is small,” said Thompson, but “would be noticeable on a (IQ) test … (it) may mean you get a couple more questions correct.  “It wouldn’t be an enormous change. Even so, it would help our brain resist cognitive decline later in life.”

The research, published in Nature Genetics, was conducted by more than 200 scientists from 100 institutions worldwide, working together on a project called Enigma.

Thompson said other studies have implicated some genes in IQ, but this was the first to link a common gene to brain size.

The team found that every T in place of a C represented a 0.6 percent smaller brain — equal to more than a year’s worth of brain loss through the normal ageing process.

Asked to comment on the research, Tom Hartley, a psychologist at Britain’s University of York said he was “a little wary of thinking in terms of a gene for intelligence.

“There are undoubtedly a lot of things that have to work properly in order to get a good score on an IQ test, if any of these go wrong the score will be worse.”  But he said it was “fascinating” to find that such small genetic changes could affect the size of critical structures such as the hippocampus, the brain’s memory centre.

“Given the importance of the hippocampus in disorders such as Alzheimer’s disease these could turn out to be very significant findings,” said Hartley.


Wednesday, February 8, 2012

IQ, conservatism and racism

On 22nd January I commented on claims by two Canadian psychologists to the effect that conservatives and racists have low IQs.  One look at the study told me that it was brainless so I just reproduced the journal abstract and pointed out two of the things that made it brainless.  I didn't see any point in a detailed look at the paper.

The study has however become much celebrated in Green/Left quarters, with the ineffable Monbiot in the vanguard.  Monbiot's entry into the discussion has however energized a few ripostes from conservatives,  with the most amusing point being that after Leftists  telling us for decades that IQ scores are meaningless they suddenly have done an 180 degree turn and treat them as highly meaningful!

I thought I might add something to what I regard as the two best conservative responses to the original article.  The first is in The Telegraph and makes a number of good points, all of which are worth reading.  

I want to say more about just one of them:  The point that IQ was measured during childhood (10 or 11 years of age) and that such measures are unreliable.  That is however a matter of degree and of purpose.  They are accurate enough to be a useful guide to who will benefit from a selective (more demanding) education, for instance.

An interesting aspect of scores at that age, however, is what I call the chimpanzee effect.  In brief, this effect is that dummies mature faster so a relatively high score in childhood can lead to a relatively low score in adulthood.  So it is quite possible that the high scorers in the data used by the Canadian authors became relatively low scorers later on. So if the high scorers in that body of data were later found to be liberals, it is quite possible that the same people were dummies in later life!  So the data could be said to show the opposite of what the authors claim.  The data could be said to suggest that it was the liberals who were the dummies.

That is all just speculation, however,  The truth is that the data are incapable of telling us which way around it went at all.

That little point is really just a bit of fun, however.  The second  article by statistician Briggs is by far the most pointed.  Briggs had a strong enough stomach to read the whole article. And when he did, he basically found that the authors had misrepresented their results.  The correlations with IQ were in fact negligible.   They were statistically significant but statistical significance is only a correction for small sample size and the sample sizes in the data used by the Canadians were large. 

So statistical significance is irrelevant.  It is other forms of significance we have to look at.  Let me put it this way:  What the Canadians found was (roughly) that out of 100 high IQ people, 51 would be liberals and 49 would be conservatives.  Such a near-even split means of course that IQ is essentially irrelevant to ideology, or is not a socially or scientifically significant predictor of ideology.

Now we come to "racism".  The correlations between conservatism and racism were more substantial.  Briggs rightly detects the flaw in that.  The correlation is between WHAT THE AUTHORS SAY is conservatism and racism and there is no external validation of either measure.  So all I want to do is draw attention to something I set out long ago:  That even eminent Leftist psychologists have NO IDEA what conservatism is.  A much noted paper in the field even identified  Stalin, Khrushchev and Castro as conservatives!   Can you get any madder than that?  So it is no wonder that when they use their questionnaires to predict how people will vote, they find that "conservatives" AS IDENTIFIED BY THEM are just as likely to vote Democrat as Republican (for instance).   How clueless can you get?  What is going on of course is that Leftist psychologists swallow hook line and sinker of Leftist propaganda about conservatives.  They believe that conservatives really are as Leftist propaganda describes them.  It would appear that they never bother to talk to any actual conservatives to find out what they really think. 

By contrast, I am a conservative so  a questionnaire that I devised based on a thorough knowledge of what conservatism actually is, did what the Leftist questionnaires could not:  Provided a substantial prediction of vote.  See here.  So once again the arrogance and ignorance of the Left has led them to a false understanding of reality and scientific work that is futile and useless.  The work by the two Canadian authors certainly tells us NOTHING about the correlations with  conservatism.  I have written more extensively elsewhere about the relationship between conservatism and IQ.

For  reference, the Canadian study is:  "Bright Minds and Dark Attitudes: Lower Cognitive Ability Predicts Greater Prejudice Through Right-Wing Ideology and Low Intergroup Contact"  by Gordon Hodson and   Michael A. Busseri

Sunday, January 22, 2012

An uninsightful look at racist attitudes

Below is an academic journal article which claims that "racists" have low IQs.  I append some comments at the foot of it
Bright Minds and Dark Attitudes

Lower Cognitive Ability Predicts Greater Prejudice Through Right-Wing Ideology and Low Intergroup Contact

Gordon Hodson et al.


Despite their important implications for interpersonal behaviors and relations, cognitive abilities have been largely ignored as explanations of prejudice. We proposed and tested mediation models in which lower cognitive ability predicts greater prejudice, an effect mediated through the endorsement of right-wing ideologies (social conservatism, right-wing authoritarianism) and low levels of contact with out-groups. In an analysis of two large-scale, nationally representative United Kingdom data sets (N = 15,874), we found that lower general intelligence (g) in childhood predicts greater racism in adulthood, and this effect was largely mediated via conservative ideology. A secondary analysis of a U.S. data set confirmed a predictive effect of poor abstract-reasoning skills on antihomosexual prejudice, a relation partially mediated by both authoritarianism and low levels of intergroup contact. All analyses controlled for education and socioeconomic status. Our results suggest that cognitive abilities play a critical, albeit underappreciated, role in prejudice. Consequently, we recommend a heightened focus on cognitive ability in research on prejudice and a better integration of cognitive ability into prejudice models.


What the article ignores is that the mental gymnastics required by political correctness are considerable.  A simple soul who sees a lot of black crime is likely to have a low opinion of blacks and say so.  But, as is often said, some ideas are so stupid that only an intellectual would believe them.  And concluding that chronic black criminality is all Whitey's fault is one such idea.  So all the study really shows is that brighter people are more able to absorb the counterintuitive but politically correct cult that the elite have made  normative in society.  Only simpler people take their views from observable reality.

And we must also note  that we are talking here about ADMITTED attitudes.  And where some attitudes are much decried -- as are racially-denominated attitudes -- the truth of any admissions can only be speculated on.  It could well be that attitude to blacks (say) is the same at all levels of IQ but only the simpler members of society are foolish enough to admit what they really think.

I could go on but I think it is already clear that this study proves nothing.

Sunday, January 8, 2012

Teens aren't too old to boost their IQ, study finds

I haven't looked at this study closely but it seems to represent  confirmation of the most favoured explanation for the Flynn effect.  The Flynn effect is that average IQ scores rose during most of the 20th century in most places.  The effect is probably the result of a number of influences but the influence generally thought most important is  increasing test sophistication.  The longer kids stay in  school the more they become "test wise" and thus increase their IQ score even though there is no increase in underlying ability.  That would certainly explain the findings below but, sadly for the hopeful, no real advantage will have been gained

 If your teenager could use a few more IQ points, Norwegian scientists have some good news: It may not be too late for junior to get them.

Many researchers now agree that mental stimulation in one's early years helps IQ to develop, but there is no such consensus that education - or anything else - can boost IQ on older kids. Studies have seen correlations between a person's total years of schooling and his or her IQ, but there's no good way to tease out the cause and effect. It could be that extra school raises IQ, but it's just as likely that those with higher IQs to start with are inclined to stay in school longer. It's also possible that some other trait, such as family income, influences both IQ and length of education at the same time.

In an ideal world, researchers would divide students into groups, give some of those groups a few extra years in the classroom and then measure everyone's IQ. If additional education was indeed an intelligence booster, then the students who spent more time in school would have higher IQs, on average, than the students who spent less time in school.

It turns out that the government of Norway conducted just such an experiment - albeit unwittingly. From 1955 to 1972, the Norwegian government required schools to increase the number of years of mandatory schooling from seven to nine. This meant that students who used to be done at age 14 now remained in the classroom until age 16. School districts didn't implement the change all at once but rolled it out over many years. This resulted in a data set that allowed researchers to slice and dice the figures in many ways - to check their work, in other words.

The other helpful thing about Norway is that the military there measured the IQ of all 19-year-old men as part of the universal draft.

Researchers from the University of Oslo and Statistics Norway (the government's bureau of statistics) matched up IQ and years of schooling and IQ for men born in 1950 through 1958. They found that each of the additional years of education raised the men's IQ by an average of 3.7 points - an increase that was deemed statistically significant. For these men, the school reform meant that they got about two additional months of education, resulting in an additional 0.6 IQ points.

The results were reported in Proceedings of the National Academy of Sciences.

"These results do not directly challenge the recent emphasis placed on early childhood environment for the development of cognitive skills," the researchers wrote. However, they added, "these results suggest that we should not yet entirely disregard the potential of interventions even as late as in adolescence."