Tag Archives: IQ

Bill Gates & Executive Functioning

25 Monday Nov 2019

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Like many of the greatest minds in STEM, Bill Gates has been accused of having a touch of autism by armchair psychologists. Others argue he is simply a nerd.

While some argue that nerdiness is a mild form of autim, others, like LOTB, argue that the two concepts are distinct.

I have not done enough research to have a strong opinion either way, but a key deficit in autism involves executive functioning.

What is executive functioning?

Executive functions (collectively referred to as executive function and cognitive control) are a set of cognitive processes that are necessary for the cognitive control of behavior: selecting and successfully monitoring behaviors that facilitate the attainment of chosen goals. Executive functions include basic cognitive processes such as attentional control, cognitive inhibition, inhibitory control, working memory, and cognitive flexibility. Higher order executive functions require the simultaneous use of multiple basic executive functions and include planning and fluid intelligence (e.g., reasoning and problem solving)

source: https://en.wikipedia.org/wiki/Executive_functions (2019-11-24)

What does any of this have to do with Bill Gates? My subjective impression is that Gates is relatively weak at EF. Perhaps not compared to the average person, but certainly compared to his super IQ matched peers. In support of this impression are three (admittedly weak) pieces of evidence.

1) He sucked at petals around the rose

If you’ve never heard of this game please check it out and record how many dice rolls it takes you to get six consecutive correct scores.

Then compare your performance to Gates’s.

This game strikes me as very similar to the Wisconsin Card Sorting Test (a common measure of EF) in that it requires you to infer a rule based on repeated feedback. I infered the rule simply from the name of the game even before any feedback.

In Gates’s defense, he thought the game was called “pedal around the roses”, so this may explain his poor score.

2) He can’t control his hands

Anyone who has watched Gates in interviews knows how erratically his hands move around when he talks. I’m no neurologist, but this strikes me as an inability to inhibit certain responses, a lack of cognitive control or self-monitoring, and poor communication between the left and right brain. I tend to overuse my hands when I talk too so I see a bit of myself in Gates but I was insecure enough about it to stop.

I also have a problem where whenever I wave to someone, I also say “hi” even though they’re often too far away to hear me. I think this relates to the huge gap between my verbal (left-brain) and performance (right-brain) IQs. In extreme cases this can lead to unbuttoning your shirt with your left hand while simultaneously buttoning it up with your right-hand, thus never getting undressed.

3) He’s not that articulate

Despite the fact that Bill Gates’s verbal SAT score equates to a spectacular verbal IQ of 157, he’s not an especially impressive impromptu speaker. As commenter ” caffeine withdrawals” noted, he’s clearly above average, but not much more than that.

A professor of linguistics informed me that based on factor analysis, linguistic ability is actually three different abilities: vocabulary, working memory, and executive functioning. We know from Gates’s sky high verbal and math SAT scores that he’s likely extremely high in the first two, so only the third factor could be dragging down his speaking skills.

How does EF affect speaking skills? EF is all about planning and if you can’t plan your sentences and paragraphs in real lime, they wont be especially succinct. EF also relates to fluency because a certain amount of flexibility is needed to find the right word to express a given thought. People who perseverate too much on one word, or one type of word, will not be smooth talkers.

Long-term IQ stability: A case study

24 Sunday Nov 2019

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Commenter illuminaticatblog was kind enough to share with us his intelligence test scores at age 12 and at age 26. Both times he took the Wechsler intelligence scales: WISC-III at age 12; WAIS-IV at age 26.

Below is a chart comparing results at both ages. I wanted to compare apples to apples so I only included the subtests that were administered on both occasions, and used only these to calculate his verbal, performance, and full-scale IQs respectively (prorating when required). I did not adjust for the Flynn effect so scores at both ages are likely slightly inflated, but to similar degrees.

  Wechsler IQ equivalent at age 12 Wechsler IQ equivalent at age 26
VERBAL ABILITIES 125 (very bright) 133 (brilliant)*
Information (general knowledge) 130 (brilliant) 140 (very brilliant)
Similarities (verbal abstract reasoning) 110 (bright) 120 (very bright)
Arithmetic (mental math) 110 (bight) 125 (very bright)
Vocabulary (word knowledge) 125 (very bright) 120 (very bright)
Comprehension (common sense & social judgement) 130 (brilliant) 115 (bright)
NON-VERBAL VISUAL-MOTOR ABILITIES 113 (bright) 99 (average)*
Picture Completion (visual alertness) 125 (very bright) 80 (dull)
Block Design (visual organization) 115 (bright) 125 (very bright)
Digit Symbol (Rapid hand-eye coordination) 90 (average) 95 (average)
OVERALL GLOBAL INTELLECTUAL ABILITY 123 (very bright) 121 (very bright)

The first thing we notice is how remarkably consistent the overall IQ is from age 12 to 26, declining by only 2 points over those 14 years, despite the incredible amount of drama the he endured over that time.

This remarkable consistency is not surprising, as the long-term stability (over 13+ years) of Wechsler IQ is in the 0.73 to 0.9 range.

Also consistent is his verbal IQ > Performance IQ gap, though this nearly triples from 12 points at age 12 to 34 points at age 26.

At the subtest level, we see a lot less consistency than we observe with the overall score. This is not surprising because individual subtests are a lot less reliable than a composite score that combines eight different subtests (allowing error in both directions to cancel out).

Given the unreliability of individual subtests and the number of subtests, it’s statistically expected to see a few big changes and one shouldn’t over-interpret this. However the 45 point drop on Picture Completion is concerning.

Picture Completion tests one of the most important parts of intelligence because visual awareness to our environment is crucial to our ability to adapt. A close friend of mine scored low on this particular subtest despite being otherwise quite bright and I was shocked when he had driven himself to my remote winter cottage on a deflated tire.

“Did you not notice one side of the car is way lower than the other?” I asked.

No he had not. He’s extremely lucky it didn’t go flat as he was driving up there, otherwise he would have found himself stranded on an unpaved deserted forest road with no cell phone reception in the pitch blackness of a cold Canadian night.

*Because he took the WAIS-IV as an adult, which does not allow for verbal or performance IQs, I had to convert using the WAIS-III.

More data on Bill Gates’s social IQ

17 Sunday Nov 2019

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For years this blog has has discussed Gates’s spectacular verbal and math IQ. But what about other parts of his intelligence?

Evidence of Gate’s social IQ can be gleaned from his performance at poker (a game involving bluffing and reading people). The late Paul Allen writes:

I spent more time with Bill at Currier House before his nightly Poker games with the local cardsharps. He was getting some costly lessons in bluffing; he’d win three hundred dollars one night and lose six hundred the next. As Bill dropped thousands that fall, he kept telling me, “I’m getting better”. I knew what he was thinking: I’m smarter than those guys.

From pages 71-72 of Idea Man by Paul Allen

Were the other players letting Gates win the first night so he would bet double the next night, or was he legitimately winning only half as often as he lost? Let’s assume the latter, in which case was likely a worse poker player than 2/3rds of the Harvard poker club.

On an abbreviated version of the WAIS-R, a sample of 86 Harvard students averaged IQ 128. Commenters Swank and pumpkinhead have argued this is an underestimate because the sample may not have been representative. On the other hand the WAIS-R norms were 25 years old, so the Flynn effect predicts IQ 128 would have been an overestimate. Error in both directions likely cancels each-other out, making 128 perhaps a plausible estimate.

Now if we assume Poker skill (like other measures of Theory of Mind) only correlates 0.43 with conventional measures of IQ, the Harvard poker club like averaged 28(0.43) + 100 = 112 in Poker IQ, and if Gates was worse than 2/3rds of them, his “Poker IQ” was likely only 107 (assuming similar practice, or assuming all had enough practice to reach diminishing returns).

So now we have two very rough estimates of Gates’s social IQ. “Fashion IQ” was 84 and “poker IQ” was 107. Both measures are of highly questionable validity, so unlikely correlate more than 0.5, thus a composite measure of his social IQ might be very crudely estimated at 95 which is extremely low compared to his his verbal and math IQ, but only slightly below the U.S. mean of 100.

Henry: Portrait of a Serial Killer (1990)

31 Thursday Oct 2019

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pumpkin person rating: 8/10

In the spirit of Halloween, I re-watched this movie a couple weekends ago. Neither Netflix, the Movie network, nor pay per view have enough selection for me, so I added Amazon Prime to boot and this film was prominently displayed in their horror section.

It’s a disturbing, well organized film based on real life serial killers Henry Lee Lucas and Otis Toole.

Psychiatrists reportedly found Toole to be be schizophrenic, psychopathic, and mentally retarded with IQ scores ranging from 54 (Trainable [moderate] Retardation) to 75 (Borderline Retardation). It’s hard to assign a single number, but assuming the lowest and highest score were from tests that correlate around 0.7, a composite IQ of 61 is implied (Educable [mild] Retardation).

Actually it’s likely his IQs was even lower because in those days people didn’t know about the Flynn effect inflating the scores of people tested using old norms.

Toole’s low IQ seems to be part of a larger pattern of neurological impairment. He was also epileptic and sexually aroused by fire and from his mug shot it seems he had asymmetrical features, suggesting genetic mutations or developmental insults..

Toole’s art therapist Dr. Joel Norris described Toole as “the lower end of the gene pool”. The genetic garbage of society. Indeed in the film his body is literally stuffed into a garbage bag.

Of course HBD deniers could argue his problems were cultural, not biological. Raised by a mother who dressed him up as a girl, a sister and male neighbor who raped him, and a grave robbing granny, the illiterate Toole drops out of school to become a prostitute and part-time transvestite. Toole’s horrific backstory is not shown in the film.

Toole would become close friends with Henry Lee Lucas, whose mother also made him wear a dress as a kid. With a much higher IQ of 87, Lucas is widely believed to have been the leader of their murder spree.

While the film never mentions IQ it does imply Lucas is the smarter of the two, warning Toole not to kill people he’s been seen with.

Although Lucas towers over Toole intellectually, both men are morons compared to a quick-witted overweight TV salesman who belittles them with biting sarcasm. Luckily the sarcasm flies above their heads, but when the high IQ salesman pushes his luck, he proves too clever by half.

IQ, social environment & DNA

17 Thursday Oct 2019

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Commenter RR argues that IQ tests measure social class. If by social class he means the home one grew up in, the following author begs to differ:

First, family has little effect on whatever cognitive abilities you have after the age of 17. While family environment is potent early on, its effects fade away to low level by age 17 and become insignificant by maturity. As you grow up, you move outside the family and go to school, become a member of a peer group (your close friends), find a job, and marry. You enter a current environment that swamps the lingering effects of family environment. Current environment is surprisingly self-contained: it influences one’s current cognitive abilities with very little interference from past environments. Most of us assume that your early family environment leaves some indelible mark on your intelligence throughout life. But the literature shows this simply isn’t so.

Second, once the influence of family disappears, the cognitive quality of your current environment tends to match your genetic quality. This is often called the tendency toward “gene-environment co-relation”. This means simply that if your genes are at the 90th percentile for cognitive ability, your current environment tends to be at the 90th percentile of the population for cognitive quality…In other words, chance events aide, genes and current environment tend to match, so whatever genetic differences exist predict cognitive performance without any need to take current environment into account.

You might think the above was written by Arthur Jensen, but it was written by Jensen’s most formidable opponent, James Flynn. It’s from pages 5 to 6 of Flynn’s book Does Your Family Make You Smarter?

Evidence in support of Flynn’s comments is a 2010 study by Haworth et al, where an astonishing 11000 pairs of twins from four different countries were intelligence tested. The results: heritability was 41% at age nine, 55% at age 12, and 66% by age 17.

66% is very similar to the WAIS IQ heritability found in the Minnesota study of twins reared apart, but Haworth et al compared the IQ correlation of MZ twins raised together with the correlation of DZ twins raised together (the classical twin study). If one assumes that both types of twins are equally similar in their environments (including prenatal), the greater IQ similarity found among MZ twins can only be explained by their greater genomic similarity. This is known as the equal environment assumption.

Critics claim that MZ twins raised together enjoy more similar environments than DZ twins raised together and so genes are getting undeserved credit for an environmental effect. However Arthur Jensen notes:

…some same-sex DZ twins look much more alike than others. In some cases their parents even wrongly believe that their DZ twins are identical twins, and they treat them as such by dressing them alike and giving them the same hairstyles and so on. But DZ twins whose parents and others had mistaken them for MZ twins are no more alike in IQ than other DZ twins or ordinary siblings who don’t look much alike.

Source: Intelligence, Race and Genetics by Frank Miele, pg 98

Indeed if people think MZ twins have more similar environments than DZ twins because they look identical, then it follows that same sex DZ twins should have more similar environments than opposite sex DZ twins because they too look more similar (and are treated more similarly) and yet the IQ correlation between same sex and opposite sex MZ twins are virtually identical.

Further support for the equal environment assumption comes from a study of 1,030 female-female twin pairs from the Virginia Twin Registry with known zygosity. About 15% of the twins disagreed with their actual zygosity, however perceived zygosity had no impact on the correlation between twins when it came to any of the five psychiatric disorders studied.

Polygenic IQ scores

15 Tuesday Oct 2019

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Commenter “Some Guy” had some questions about polygenic scores for me. His questions are in block quotes with my answers directly below each one.

How good do you think polygenic scores will have to get before they start getting used on an individual level? Like within how many SDs of the true IQ/g/educational achievement?

If one’s polygenic score is extreme enough, it doesn’t have to be very accurate at all to give useful information. For example, let’s say you have several embryos to choose from and one has a polygenic education score of +5 SD. Even though such scores only predict 12% of the variance, because +5 SD is so extreme, you can be about 97% confident that embryo will grow up to be more educated than the average person (assuming he or she is raised in a society similar to the one from which the stats were derived).

One problem with polygenic scores is they don’t seem translate well from one culture to another, suggesting they’re more correlative than causal.

The uses I can think of is to identify children with high potential from poor backgrounds, or as an environmentally unbiased entrance “exam” for schools etc.

What I would like to see them be used for is to estimate the IQs of historical Geniuses like Albert Einstein and to estimate the IQs of ancient human populations. For example Richard Klein believes there was a major genetic change in human cognition that occurred about 50 kya that allowed us to suddenly spread from Africa, replace the Neanderthals, colonize the globe and create representational art. If we compared the polygenic scores of humans both before and after the upper Paleolitic revolution, we could test this idea. Similarly Gregory Clark believes rapid genetic evolution in Europe allowed the industrial revolution.

I would also love to see polygenic IQ scores for the Neanderthals, assuming they would be meaningful in a group that culturally and genomically distinct.

What sort of PGS-IQ correlation would result in polygenic scores that are say within 1 SD of the true IQ? I know you often calculate standard errors from correlations, mind sharing the formula/method?

Within 1 SD with degree of certainty? If you mean with 95% certainty, you would need a correlation of 0.85+ which I doubt will ever be achieved. Even the correlation between two different IQ tests is seldom that high.

The method is to square the correlation to get the percentage of the variance explained, and then subtract that value from 1 to see what percentage is left unexplained.

So for example a PGS that correlated 0.85 with IQ explains 72% of the IQ variance, thus leaving 28% unexplained.

The variance is defined as the standard deviation squared, so since the IQ standard deviation is set at 15, the variance is 225, and 28% of 225 is 63.

The square root of 63 is 7.9 which is what the standard deviation would be if everyone had the same PGS. This is also known as the standard error of the estimate. Now in a bell curve, 95% fall within 1.96 of the mean, so multiplying 7.9 by 1.96 tells us that 95% of say the UK, will have IQs within 15.5 points of the PGS prediction.

So if you have a PGS of +2 SD that correlates 0.85 with IQ, your IQ will likely be 0.85(2) = +1.7 or IQ 126, with a 95% confidence interval of 111 to 142. But of course we’re nowhere near seeing a 0.85 correlation.

To get the general public to really trust polygenic scores for IQ, I’d guess the accuracy would have to be within 5 points of the true score. Within 10 points would lead to people who actually differ by 20 points regularly ending up with the same polygenic score. Since 20 points tend to be the difference between leaders and followers, such errors would be highly noticeable.

I think if they achieved a correlation of 0.7 with IQ they’d be considered credible (especially if the predictive power was maintained across oceans and generations). That’s the correlation between different IQ type tests with each-other and these are routinely used to decide issues as important as who gets into an elite college, who gets excluded from the military, who gets diagnosed as disabled or gifted, and who gets sentenced to death by the courts.

By the way, what do you think about this argument against people who consider intelligence entirely environmental: If that really was the case, then disadvantaged people would NEVER be smarter than people with good backgrounds. So why even bother giving people from poor backgrounds a chance? 100% environmentalism leads to un-egalitarian conclusions, and is easily disproven by the existence of smart disadvantage people.

It’s prima facie absurd, but it wouldn’t necessarily lead to the conclusion that we shouldn’t give deprived people a chance. On the contrary it might lead to the conclusion that changing IQ is simply a matter of changing environments.

A closer look at Bill Gates’s IQ

13 Sunday Oct 2019

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Bill Gates reportedly scored 1590 on the SAT in the early 1970s (Verbal 790 + Math 800). In a rare study done in 1974, it was estimated that if all American teens took the SAT that year (instead of just the college bound elite) , the verbal mean would be 368 (SD 111) and the math would be 402 (SD 112). Assuming a 0.67 correlation between the two subscales, a combined mean of 770 (SD 203.8) is implied.

Thus Gates’s scores equated to a verbal IQ of 157, a math IQ of 153+, and a combined IQ of 160.

However these numbers assume the SAT was normally distributed, and yet empirical data from the 1980s suggests near perfect scores were much more rare than the normal curve predicts and equated to an IQ of about 170 and if anything they were likely even more rare in the 1970s when fewer people studied for the SAT.

Another reason why these numbers likely underestimate Gates’s IQ is that he hit the ceiling on the math section.

Thus I found the following part of a 2001 article in Time magazine of interest:

“In ninth grade,” Gates recalls over dinner one night, “I came up with a new form of rebellion. I hadn’t been getting good grades, but I decided to get all A’s without taking a book home. I didn’t go to math class, because I knew enough and had read ahead, and I placed within the top 10 people in the nation on an aptitude exam. That established my independence and taught me I didn’t need to rebel anymore.” By 10th grade he was teaching computers and writing a program that handled class scheduling, which had a secret function that placed him in classes with the right girls.

According to this source, there were 4,097,000 Americans born the same year Gates was.  Some of them would have died before reaching the ninth grade, but these probably would have been made up for by immigrants, so Gates being in the top ten in the nation for his age or grade level, implies he scored in the top one in 409,700.  This equates to a math IQ of 168.

In other words, had the SAT had a higher ceiling in the 1970s, he would have perhaps scored 910 (the equivalent of IQ 168). Add this to his verbal score of 790, and we get a combined score of 1700, which would have equated to a combined IQ of about 170. So even if we assume 1970s SAT scores were normally distributed, Gates still clocks in at IQ 170 as long as we extend the ceiling.

Commenter Bruno has expressed considerable skepticism about Gates having an IQ this high, citing the fact that he was not the top math student at Harvard.

My response is that a) standardized test scores should be given more weight than school grades, and b) Gates spent his teens obsessing over computers so math IQ made him the best programmer at Harvard instead of the best math student per se. The title of best math student probably went to an equally smart person who spent their teens obsessing over math.

The video clips are from the fascinating new Netflix series Inside Bill’s Brain.

It seems Gates has really mellowed out in recent decades, or at least become better at hiding his arrogance. In the below clip you can see him berating his employees and making a bizarre head twirling facial expression as if implying the employee is mentally retarded.

Indeed with an IQ of 170, even the average member of America’s political, economic, and cultural elite (IQ 125 to 135) is literally mentally retarded compared to Gates, which helps explain how he was able to leapfrog over the establishment to become the richest man of the 20th century, with such a stranglehold over the market that it took the U.S. justice department to stop his complete domination.

Robert Mugabe’s IQ

02 Wednesday Oct 2019

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photo taken July 1, 1984. ALEXANDER JOE/AFP/Getty Images

Several people have asked me to estimate the IQ of late Zimbabwean leader Robert Mugabe.

According to the latest research by Richard Lynn and David Becker, the average IQ of sub-Saharan Africa is 69 however I would argue that if the data is limited to the most culture reduced tests (and I don’t mean the Raven, which is deceptively culturally loaded), it would be about 80 (UK norms/white norms). It’s important to use the most culturally reduced tests when comparing populations separated by time or space, otherwise you get ridiculous results like average IQ increasing by 7 points a decade as happened in Holland on the Raven test.

80 is 20 points the white mean of 100. If black Africans average 20 points below white populations on truly culture reduced tests, then perhaps their leaders average 20 points below the white leaders of mostly white countries.

Publicly available data suggests U.S. presidents have an average IQ of 130 (with an SD of only 12 compared to the national white SD set at 15), so let’s say black African leaders have an average IQ of 110 (SD also 12).

However Mugabe was not just any black African leader. He was exceptionally well educated, even by the standards of World leaders.

To compare Mugabe’s education to other African leaders of his generation, I found a list of the oldest presidents in Africa and tried to determine how many degrees each had. Excluding non-black leaders, the 8 oldest held the following number of degrees:

Paul Biya 4, Manuel Pinto da Costa 0?, Alpha Condé 2?, Arthur Peter Mutharika 2, Hage Geingob 3, Teodoro Obiang Nguema Mbasogo 0?, Emmerson Dambudzo Mnangagwa 2?, Alassane Ouattara 3.

The mean is 2 with a standard deviation of 1.41

So with an astonishing seven university degrees Mugabe is 3.55 SD more educated than even a group as elite as African presidents

In sub-Saharan Africa, the correlation between culture-reduced IQ and education appears to be 0.52, but in a group as homogeneous as African presidents, it would likely be lower. What is needed is the IQ vs education correlation among a specific occupation (African Presidents).

On page 345 of his book Bias in Mental Testing, Arthur Jensen shows the partial correlation between IQ and education, that is the correlation holding occupation constant. This correlation is listed as 0.27 to 0.42 (see below). Let’s split the difference and say 0.35 and assume the same correlation in Africa..

Assuming Mugabe is 3.55 SD more educated than the average African president, the partial correlation predicts his IQ would be 0.35(3.55 SD) = 1.24 SD higher than the average African presidents.

Assuming African presidents have a mean IQ of 110 with an SD of 12 (see above), this would put his expected IQ at 125 (higher than 95% of white America).

All we can say with 95% certainty is that his IQ would be anywhere from 103 to 147. One reason for thinking he’s in the upper end of this range is that he was a Marxist, and left-wing politics are positively correlated with IQ (at least if you control for race and income).

Whatever his IQ, it would have likely been substantially higher had he been born and raised in the United States, where First World nutrition would have allowed his brain size to reach its genomic potential.

One caveat to the above analysis: usually education is measured by highest degree obtained, not number of degrees. How this might affect the correlation with IQ is unclear.

A cross-cultural study of university students

02 Wednesday Oct 2019

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A 2015 paper by Kate Cockcroft et al., compares the scores of 349 British middle class university undergrads to 107 lower class black South African undergrads on the WAIS-III (UK edition).

The results were as follows:

The UK students averaged a full-scale IQ of 106.95 (UK norms) while the South Africans averaged IQ 93.27. However because this study was published 18 years after the UK WAIS-III was published, we should adjust for the Flynn effect.

The single best source on recent Wechsler Flynn effects is Weiss et al., 2015  which found that full-scale IQ has been increasing by 0.31 points per year, at least in U.S. children. If we assume it’s the same for UK adults, then the UK students have an adjusted IQ of 101 and the South African students have an adjusted IQ of 88.

What’s more interesting to me is how they did on the culture reduced tests since that’s the more fair comparison.

 
Test: Digit Span scaled score Flynn adjusted Digit Span  scaled score Flynn adjusted Digit Span IQ equivalent Block Design scaled score Flynn adjusted Block Design scaled score Flynn adjusted Block Design IQ equivalent Compoite IQ based on adjusted scores on both tests
UK undergrads 9.5 9.32 97 10.66 9.76 99 98
Black South African undergrads 9.35 9.17 96 8.67 7.77 89 91

So on a composite score of the most culture reduced spatial & non-spatial test (Block Design & Digit Span), Black South African undergrads average IQ 91. This is 11 points higher than the average Black South African seems to score on the same culture reduced tests.

As of 2013, only 16% of South Africa’s black young adults were attending higher education (compared to about 55% of whites, 47% of Indians and 14% of Coloureds). Thus, simply attending university puts one in the top 16% of this demographic, with the median South African university student being in the top 8%. If there were a perfect correlation between IQ and education, the median South African black university student would have an IQ 21 points higher than the average black South African. In reality his IQ is only 11 points higher, suggesting a correlation of 0.52 (at least on the most culture reduced tests).

This is similar to the 0.57 correlation between IQ and education observed in the United States.

IQ, board games & test construction

31 Saturday Aug 2019

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IQ tests are considered valid because they have both construct validity and predictive validity. They have construct validity because a statistical technique called factor analysis proves that all mental tests are influenced by a general factor dubbed g, and that IQ tests load high in g. They have predictive validity because IQ tests better predict important life outcomes like education, income and occupational status than any other single measurable trait.

However IQ skeptics like our very own Race Realist (RR) argue that this validity is just an artifact of test construction. In other words, all IQ tests correlate with g, not because they measure a factor common to all mental abilities, but rather because only tests that are positively correlated are included in test batteries.

Similarly, he’d argue that IQ tests predict success in school and life, not because high IQ people learn faster, make wiser life choices and are more productive, but rather because only test items that good students did well on were included in the tests.

There’s some truth to RR’s view. Tests of general knowledge only became used in IQ tests after WWI testing found them to correlate highly with the total score of other subtests. In addition, David Wechsler would present potential test items to people of “known intelligence” and primarily those items that discriminated well between people with known Binet IQs of different levels were included. A question about a non-Christain religion was included in the general knowledge subtest after Wechsler found it to distinguish those Americans with superior from average IQs.

Given that IQ tests owe at least a small part of their validity to test construction, it’s interesting to ask whether IQ tests would still have the same construct and predictive validity if we remove the selective bias in picking subtests and test items.

What is needed is a random sample of mental abilities, not one pre-selected by psychologists. The closest thing we have to such a sample are board games. Thus, instead of the 10 subtests Wechsler arbitrarily chose for his original scale, we could simply pick the 10 “most popular” board games of all time:

  1. chess
  2. checkers
  3. Backgammon
  4. Scrabble
  5. Monopoly
  6. Clue
  7. Othello
  8. Trivial Pursuit
  9. Pictionary
  10. Risk

An ideal study would be to take 2000 random teenagers with very little experience playing any of these games, and send them to a summer camp where all they did was play these 10 games everyday (though no special strategies would be taught), culminating in a tournament where all 2000 were ranked on each game, and then given an overall ranking that reflected their combined performance across all ten games. This combined ranking would be converted into full-scale IQ, such that the best overall player (out of 2000) would be assigned a full-scale IQ of 150 and the worst would be assigned a full-scale IQ of 50.

If there really is a g factor, we should expect that while some people are great at chess but terrible at Pictionary, in general people who are good or bad at one game would be good or bad at any other.

Further, if g has predictive validity, we should find that 30 years later, those with the highest full-scale IQs would have more education, more prestigious occupations, and higher incomes (even after controlling for family background) than those who performed poorly.