It’s common knowledge in psychometrics that U.S. whites average about one standard deviation (15 IQ points) higher than U.S. blacks and have done so since the first mass tests were administered in WWI.
But could the gap extend much further in space and time? Tens of thousands of years further.
At first it sounds absurd: there were no IQ tests 15,000 years ago, and there weren’t any white people. The earliest Europeans had dark skin, and they were largely replaced by Middle Easterners spreading agriculture.
Archaic European
Nonetheless, there were people living in Europe 15,000 years ago and to the degree they resemble today’s Europeans (phenotypically and genetically) they’re a proxy for archaic whites.
Similarly, the oldest lineage in Africa are Bushmen, and to the degree they resemble modern Africans, they’re a proxy for archaic blacks.
The archaic whites left the following rock art over 15,000 years ago.
IQ 74 (1963 US norms)IQ 144 (1963 U.S. norms)
The archaic blacks left the following rock art, perhaps much more recently.
IQ 74 (1963 U.S. norms)IQ 118 (1963 U.S. norms)
When I asked readers to rate the two archaic white paintings using the quality scale of the Dale-Harris Draw-A-Man test, the median votes were 3 and 11, giving the archaic whites a mean score of 7.
votes for the first European paintingvotes for the second European painting
For archaic blacks, the median votes were 3 and 8, giving archaic blacks a mean score of 5.5.
votes for the first African painting
votes for the second African painting
That’s a difference of 1.5 points. Since the standard deviation for incipient adults (age 15) on the Goodenough-Harris quality scale is 1.7, archaic whites over 15 thousand years ago were already nearly one standard deviation (15 IQ points) higher than archaic blacks living later.
From Children’s Drawings as Measures of Intellectual Maturity by Dale B. Harris
Of course with such a tiny sample size, this conclusion is EXTREMELY tentative and requires far more research.
It is most ironic that the Draw a Man test was invented by a woman and that girls outscore boys, but in the 1920s, women were devalued. The great Florence Goodenough realized that as children got older, their drawings became more sophisticated and thus could be used as a proxy for mental age. Goodenough’s test was not a good measure of IQ, but at times it was good enough (get it?).
When the test was revised in 1962 by Dale Harris, not only did he add a “Draw a Woman” subtest, but he added a quality scale so that rather than spending half an hour going through a long checklist of dozens of different criteria, psychologists could just compare a drawing they were scoring to a progression of drawings ranked from level 1 (crude stick figure) to level 12 (a detailed sketch) and judge which level it most resembled. This may sound subjective, but different judges gave very similar scores (though today machine learning could probably improve objectivity).
What I love about the quality scale is that when they were making it, they instructed the judges to divide all the drawings they reviewed into 12 separate piles such that difference in quality between each pile was equal. This makes the raw scores a true interval scale, unlike most tests which are only ordinal scales.
Please study the progression of drawings from 1 to 12, and notice how as you move up the scale, you get a gradual and consistent improvement in accuracy, detail and proportion (with no sudden jumps in quality). Based on the linear progression, try to imagine a drawing that would merit a level 13 or 14 etc if the scale extended that high:
Now please compare the below drawings which I’ll be discussing in future articles to the quality scale and vote on where they should rank. Please vote before wondering who drew them or reading the comments since that could bias your judgement. Please be as objective as possible. Consider the level of maturity of each drawing (using the above quality scale as a guide), not whether you like or dislike it.
Although all drawings should be of men, in some cases artists took certain liberties (i.e. head of a bird etc). In such cases use your best judgement to decide what score the drawing merits.
I could have scored these myself but it seems more objective and scientific to rely on the wisdom of crowds:
On page 206 of Bias in Mental Testing, Arthur Jensen writes:
Not sure why Jensen considers all these correlations positive, unless zero is a positive number (I consider it neutral).
And I’m not sure why some commenters think weight lifting requires coordination when the correlation between strength (hand grip, chinning) and coordination (Pursuit rotor tacking, Mirror star tracing) is zero.
But maybe these are not the best measures of strength or coordination (mirror star tracing sounds more like a cognitive test than a physical one), but when I lift weights, I don’t feel like I’m using coordination. To me coordination is best measured by very fast paced tasks that require moving multiple body parts with exquisite timing.
Physical coordination probably correlates more with IQ than does any other physical ability. Daniel Seligman writes:
Contrary to certain stereotypes about athletes and intellectuals, physical coordination is positively correlated with IQ. Technical studies by the U.S. department of Labor report a 0.35 correlation between coordination and cognitive ability.
0.35 is very similar to the correlation between IQ and brain size; so there are at least two physical traits (brain size and coordination) that correlate moderately with IQ.
Some might argue that physical coordination is a part of intelligence since it’s largely a brain function. I define intelligence as the ability to use whatever physical traits one has as a tool to exploit whatever environment one’s in. I see coordination as one of those physical traits used as a tool by intelligence rather than part of intelligence itself, but it’s a meta-tool in that it controls the body which in turn controls the external environment.
The problem with including physical coordination in our definition of intelligence is that intelligence is only important because it’s what separates man from beast, and physical coordination fails to do that. Even if it were possible to put a man’s brain in a cheetah’s body, he would not be able to exploit the environment because his brain’s not evolved to control the cheetah’s body. But if a man’s brain could control what the cheetah did with its motor control, only then would the cheetah display the goal directed adaptive behavior we know as intelligence.
It’s like the Master Blaster character in Mad Max: Beyond Thunderdome. If Master’s brain was literally put in Blaster’s body, he might not have the coordination to win so many fights, but by telling Blaster how to use his coordination, he has given him his mind.
Feelings control intelligence
Intelligence is often defined as the mental ability to problem solve, but something is only a problem if it’s bothering us (i.e. cause us to feel pain or discomfort). Hence, feelings define the problems we use our intelligence to solve.
Intelligence controls physical coordination
Once our intelligence decides what behavior will solve a problem most efficiently, our physical coordination must direct our muscle movements accordingly. One could argue coordination itself is a mental ability and thus part of intelligence however by definition, abilities are only mental if they don’t cluster with sensory or motor functions, and physical coordination clusters with the latter. Even though coordination is part of the brain, it’s not fully part of the mind. It’s more neurological than mental per se.
In the Minnesota Transracial Adoption study, white babies, black babies, and mixed babies (biological father black; biological mother white) were adopted into white upper middle-class homes when they were 19 months, 32 months, and nine months respectively. The purpose of the study was to determine how much of the 15 point black-white IQ gap in the United States is genetic.
In 1975, the children and adoptive parents were IQ tested on at least an abbreviated versions of the Stanford Binet/WISC/WAIS (depending on age), and then retested in 1986 on the WISC-R/WAIS-R depending on age. Here are the results:
Source: page 474 of The g Factor by Arthur Jensen
Because the norms on all the tests were out-dated at the time of testing (especially in 1975), John Loehlin attempted to correct all scores for the Flynn effect.
But many people ignore the IQs themselves, and instead just focus on the IQ differences. They see that at age 17, adopted whites scored 7.1 points higher than adopted mixeds in the unadjusted data, and 16.2 points higher than the adopted blacks, and conclude that the 15 point black-white IQ gap in the United States is roughly 100% genetic.
One problem with this is that black babies were adopted later than the non-black babies. Another problem is they were born to black mothers, while the non-black babies were all born to white mothers, so the prenatal and perinatal environments may have been quite unequal.
Thus I have always been more intrigued by the 7.1 IQ gap between the adopted whites and adopted mixeds. Since the adopted mixeds presumably had only half as much black ancestry as the typical U.S. black, it’s interesting that there’s roughly half the infamous 15 point black-white IQ gap, despite being gestated in white wombs and raised in white homes. Does this point to the importance of genetics?
Physicist Drew Thomas argues that the comparison between the adopted whites and adopted blacks is misleading because in the tables posted above, at both ages we only see data for the adopted kids who remained in the study for the follow-up testing in 1986. He argues that several low IQ adopted white kids dropped out of the study, and had they remained, the IQ gap between the adopted whites and adopted mixeds would have perhaps been only 3.5 points at age 17.
However this argument is starting to feel a little post-hoc. When you do a study, your data is what it is. You can’t adjust it for what it would have been had people you wished remained in the study. Almost any study can be debunked if we imagine how it would have turned out in a parallel universe where different people took part.
That’s not to deny that adjusting for attrition can be important in some cases, but in this study, Thomas argues attrition only increased the IQs of adopted whites and not the adopted non-whites. An effect that only affected one demographic sounds to me like random error, not a systematic bias that needs to be adjusted for. And if the error was random, one could just as easily argue the IQs of adopted whites were too low before the attrition rather than too high after the attrition.
Indeed if the adopted white sample is so easily skewed by a few kids dropping out of the study, then maybe that sample is too small to begin with, and instead we should compare the much larger sample of adopted mixeds not to the adopted whites, but to the general U.S. white population.
At an average age of 17, the adopted mixeds took the WISC-R and WAIS-R depending on age, and averaged 98.5 (93.5 after adjustments for the Flynn effect, since WISC-R and WAIS-R norms were 14 and 8 years old respectively at the time of testing).
However some top-secret research I’ve been slowly doing over the past decade suggests the Flynn effect has been wildly exaggerated, so while I don’t think their average IQ was as high as 98.5, I also doubt it was as low as the Flynn corrections say. Let’s split the difference and say 96 (U.S. norms).
By contrast, the whites in the WISC-R and WAIS-R standardization samples averaged 102.2 (standard deviation (SD) = 14.08) and 101.4 (SD = 14.65) respectively. Let’s split the difference and say 101.8 (SD = 14.4).
Thus converting to the more traditional scale where the U.S. white mean and SD are set at 100 and 15 respectively, the adopted mixed mean of 96 becomes ((96 – 101.8)/14.4)(15) + 100 = 94.
In other words, despite being gestated in white wombs and raised in upper-middle class white homes, having just one U.S. black biological parent appears to have reduced IQ by 6 points, suggesting that having two U.S black biological parents would reduce IQ by 12 points, suggesting that 80% of the 15 point black-white IQ gap in the U.S. is genetic. 80% squared is 0.64 which is similar to the 0.69 heritability of the WAIS full-scale IQ found in Thomas Bouchard’s study of identical twins reared apart, consistent with Jensen’s default hypothesis which claimed that IQ gaps between U.S. races are caused by the same nature-nurture mix that occurs within them.
To paraphrase President Obama, there is no black America or white America; from a nature-nurture perspective, there’s just America.
While this analysis seems to have controlled for the prenatal and family environment, it’ does not control for peer groups. Maybe as mixed kids raised in white homes, they were unmotivated on IQ tests because of the racist stereotype that being smart = acting white. On the other hand, they did better on scholastic tests than they did on formal IQ tests, suggesting motivation was not a problem.
If the genetic part of the U.S. black-white IQ gap is indeed 12 points and black Americans are only about 74% black on average it implies that 100% West African ancestry would reduce IQ by 16 points below the U.S. white mean (at least if we assume U.S. black ancestry is representative of West African ancestry).
And at least if we assume the Phenotype = Genotype + Environment model
Some readers invoke a reaction norm model where genotype A is higher IQ than genotype B in environment A, but lower than genotype B in environment B. Assuming such norm crossing occurs with IQ, my sense is that it would be limited to individual cases and cancel out in group level comparisons like the black-white IQ gap.
Some might argue that it’s inappropriate to compare adopted mixeds to the general U.S. white population because adopted mixeds might not be genetically representative of their parent populations. In The g Factor, Jensen states that the parents of the mixeds averaged 12.5 years of schooling (page 473) while just the mothers averaged 12.4 (page 478). From here we can deduce that the fathers averaged 12.6.
In 1975 America, white women and non-white men age 25+ had a median of 12.3 and 11.3 years of schooling respectively (see table 4 of this document). Comparable figures in 1986 were 12.6 and 12.5. So using education as a proxy, there’s no reason to think the mixed kids were selected to have lower IQs than the mean of their parent races. If anything, their biological fathers averaged more education than age 25+ non-white men throughout the full duration of the study and their biological mothers averaged about the same education as age 25+ white women.
Of course it would help to know the exact ages of the parents, rather than just lumping them in with everyone over 25. I can’t find the age of the biological parents of the mixeds specifically, but the bio moms and dads of all the kids who took part in at least part of the study (see table 3 of this paper) averaged 21.6 and 26.3 at the time the kids were born, and thus were about 29 and 33 in 1975 and about 39 and 43 in 1986, thus they were likely near the median age of the 25+ cohort by the end of the study.
Although this study shows the black-white IQ gap is highly genetic, several similar studies beg to differ. Tizard (1974) compared black, white and mixed-race kids raised in English residential nurseries and found that the only significant IQ difference favored the non-white kids. A problem with this study is that the children were extremely young (below age 5) and ethnic differences in maturation rates favor black kids. A bigger problem with this study is that the parents of the black kids appeared to be immigrants (African or West Indian) and immigrants are often hyper-selected for IQ (see Indian Americans).
A second study by Eyferth (1961) found that the biological illegitimate children of white German women had a mean IQ of 97.2 if the biological father was was a white soldier and 96.5 if the biological father was a black soldier (a trivial difference). Both the white and mixed kids were raised by their biological white mothers. One problem with this study is that the biological fathers of both races would have been screened to have similar IQ’s because at the time, only the highest scoring 97% of whites and highest scoring 70% of blacks passed the Army General Classification Test and were allowed to be U.S. soldiers. In addition, 20% to 25% of the “black fathers” were not African-American or even black Africans, but rather French North Africans (non-white caucasoids or “dark whites” as they are sometimes called). In addition, there was no follow-up to measure the adult IQ of the children.
A third study by Moore (1986) included a section where he looked at sub-samples of children adopted by white parents. He found that nine adopted kids with two black biological parents averaged 2 IQ points higher than 14 adopted kids with only one biological black parent but the sample size was quite small, I don’t know anything about the bio-parents and again, no followup when the kids were older.
Forbes magazine just came out with their annual list of the 400 richest Americans and, for the 21st year in a row, Bill Gates tops the list, with over $80 billion. Just to qualify for the Forbes 400 this year, you need about $1.5 billion. It’s interesting to speculate on what Bill Gates’ IQ might be. In India, Gates was asked exactly that, though he didn’t give a number:
Way back in 1997, columnist Dan Seligman wrote the following:
It seems marvelously symbolic that William H. Gates III, the guy listed as number one on The Four Hundred, has an obviously breathtaking IQ. The figure 170 keeps getting into print, which would make him almost certainly the highest on this list or any other list you’re likely to be looking at soon. To be sure, one occasionally sees conjectures that Steven Ballmer, Microsoft’s executive vice president, worldwide sales and support, is in the same IQ league as Bill himself. Ballmer is number six among The Four Hundred. It also seems symbolic of the new order that their company has made IQ a public and explicit criterion for hires of senior personnel.
Anyhow, it seems reasonable to view The Four Hundred as a subset;an especially lucky subset;of the emerging cognitive elite.
One wonders where the 170 figure originated. I remember leafing through one of Gates’ biographies and seeing a quote from a teacher estimating his IQ to be about 160 or 170, but no actual test score was cited. So my guess is that’s where the 170 figure started. It’s also been widely reported that Gates scored a perfect 800 on the math section of the notoriously difficult old SAT (before the test was dumbed down circa 1995). Reports about his verbal score are a little inconsistent. For example, biographers Stephen Manes and Paul Andrews write:
Toward the end of the year, Lakeside senior classman Bill Gates took on a different marketing project: the selling of William Henry Gates. Potential customers? College admissions officers. Bill had scored 800 on his math SAT and five achievement tests (although only in the low 700s on the verbal SAT), and he put it, “I wanted to know which personality of mine would appeal to the world at large.
This would imply an overall SAT score in the low 1500s (which is spectacular for the old SAT) however in this Q&A, the interviewer states the Gates got an even more impressive 1590, and asks Gates if he ever wonders what question he got wrong. Gates replies:
The truth is, that was the verbal SAT. I got 790 the first time. I told my parents their vocabulary wasn’t large enough. I was criticizing them. So I did go back and take it and do better the next time.
Kind of clever how Gates managed to look like he was answering the question without actually confirming or denying the 1590 score. Assuming Gates did score 1590 on the old SAT, then according to the Prometheus MC Report (see section 8.3.3), that equates to a WAIS IQ of 169, or roughly 170. Even if he only scored around 1500, that would still equate to an IQ of 151 (99.97%ile). Either way, the man is likely smarter than the average Ivy League professor, the average Nobel prize winning scientist, and any American president of the last 100 years.
However even the old SAT might not have contained enough truly novel and complex problems to gives Gates an accurate test score. More informative are the opinions of his classmates at Harvard who actually got to observe him compete in an extremely high level academic environment. Despite writing a fairly negative book about Gates, Paul Allen admits his former friend was brilliant, stating:
I was decent in math, and Bill was brilliant, but by then I spoke from my experience at Washington State. One day I watched a professor cover the blackboard with a maze of partial differential equations, and they might as well have been hieroglyphics from the Second Dynasty. It was one of those moments when you realize, I just can’t see it. I felt a little sad, but I accepted my limitations. I was O.K. with being a generalist.
For Bill it was different. When I saw him again over Christmas break, he seemed subdued. I asked him about his first semester, and he said glumly, “I have a math professor who got his Ph.D. at 16.” The course was purely theoretical, and the homework load ranged up to 30 hours a week. Bill put everything into it and got a B. When it came to higher mathematics, he might have been one in a hundred thousand students or better. But there were people who were one in a million or one in 10 million, and some of them wound up at Harvard. Bill would never be the smartest guy in that room, and I think that hurt his motivation. He eventually switched his major to applied math.
Is Harvard math really so selective that even one in a 100,000 talent plus hard work only gets you a B? If so, it would imply Gates has an IQ of 164.
Regarding Gates academic ability, I think the general consensus from people who knew him at Harvard was that he may not have the very best at mathematics, but that he was second to none in computer science. He was taking graduate courses as a freshman and apparently never taking notes and blowing the curve for the rest of the class. A doctoral student said that Gates would just sit with his arms behind his back and correct the algorithms being written on the board anytime the prof made a mistake. He also said everyone else in the class hated him, but that he would ask him questions on occasion, and that his answers were always penetrating and beyond anything this guy could have thought of on his own.
Gates apparently wrote an outstanding paper in theoretical computer science that solved a problem presented to him a math class that he co-authored with his professor who is now at UC-Berkeley.
Sounds like Gates has an IQ of at least 160 and possibly 170. Considering the average American has an IQ around 100 and the average self-made billionaire has an IQ around 130, is it any wonder Gates became the richest man in America? Compared to Gates the average self-made billionaire is mildly retarded, and the average American is so profoundly retarded they can not even feed themselves. Becoming the richest man in the country must have been like taking candy from a baby. At his peak, he was the first centibillionaire in world history, and probably would still be that rich had potentially jealous government officials, perhaps eager to take a nerd down a peg, decided not to go after him.
I really admire Gates because instead of being the typical high IQ nerd who just sits around playing computer games or working in academia, he decided to go out into the real world and compete with the alpha males at their own cutthroat game of Darwinian capitalism…and he beat the living shit out of them!
These findings are consistent with my previous speculation that most career tracks have cognitive floors, and once you are above the cognitive floor, having additional higher IQ isn’t of much use. The cognitive floor for management positions in corporations seems to be around 110 or so. After that, getting promoted requires personality traits that are correlated with “fitness for the military” rather than higher IQ.
This idea that IQ is quite important below a certain threshold, but quite unimportant above that same threshold is very popular and potentially true, but I’ve always preferred a simpler model that splits the difference: IQ is mildly important across virtually all levels.
I don’t know if my simple model is true, but the paper seems to show that minor CEOS have a mean IQ of 108 and major CEOs have a mean IQ of 115. Now the paper defines minor CEOs as CEOs running 8 figure companies ($15 million or less) and major CEOS as running a 10 figure company (more than $1.5 billion USD). From here, we can speculate, that for every tenfold increase in company size, the average IQ of the CEO increases by 4 points. So:
Million dollar companies: Average CEO IQ 104
Ten million dollar companies: Average CEO IQ 108
Hundred million dollar companies: Average CEO IQ 112
Billion dollar companies: Average CEO IQ 116
Ten billion dollar companies: Average CEO IQ 120
Hundred billion dollar companies: Average CEO IQ 124
Trillion dollar companies: Average CEO IQ 128
Ten trillion dollar companies: Average CEO IQ 132
Of course there’s no such thing as a ten trillion dollar company, however the sitting president of the United States is often described as America’s CEO. The United States has a GDP of about 17 trillion and preliminary data suggests that U.S. presidents have an average IQ around 130, about what you’d expect from the CEO of a company the economic size of America.
So I don’t necessarily agree that the importance of IQ suddenly drops beyond a certain threshold; instead I see IQ as mildly but equally important across virtually the full range, but I could be wrong because comparing presidents to CEOs is not exactly an apples to apples comparison, and an economist could probably come along and rip this analysis to shreds.
The Lion of the Blogosphere also writes:
The problem here is that while an IQ of 110 to 115 is high enough to get promoted through the corporate ranks, it’s not smart enough to make smart decisions about the direction of the business. This explains why most corporations are so poorly run and continually make costly business mistakes.
I agree with this 100% but I would go a lot further and say that an IQ of 130 is not smart enough to be president of the United States. That doesn’t mean there haven’t been terrible presidents with IQ’s way above 130 and excellent presidents way below 130, but the lower IQ great presidents were probably great in spite of their lower IQ’s, not because of them; or because of certain personality traits correlated with lower IQ, rather than the lower IQ itself being beneficial. In fact I think the job of an American president is so complex that none of them have been smart enough for the job, and that’s probably why the correlation between IQ and job performance among presidents is so low. When everyone is in over their heads, success and failure will be largely determined by luck.
Influential blogger Steve Sailer has a recent post questioning the popular feel-good idea that bullies are low self-esteem losers. While this stereotype might be generally true, many bullies are probably high self-esteem winners, who go on to achieve great success in life. Sailer cites the following quote from sociologist Robert Faris:
On average, the future for bullies is bleak. They tend to come from homes that are problematic, and then end up having long-term problems. But there’s a caveat to that: another category of kids who are highly aggressive, kids who come from good homes, kids who are often quite popular. Those children are probably more skillful in the way that they use aggression. They often have high social skills, and do quite well in later life. There are probably a number of politicians and successful business leaders who fall into that category.
Upon reading that, I immediately thought of Chris Hargensen, the attractive rich female bully with a tested IQ of 140 from Stephen King’s novel Carrie. I was also reminded of blog commentator Santoculto’s assertion that many highly successful people are sociopaths. But the corollary is that many extreme losers (i.e. people living in abject poverty) should have towering morality; and indeed many spiritual teachers vow to give up all material possessions.
I would think that sociopathy would be even more advantageous in politics than business because politicians often have to make decisions of war and peace for political reasons so it would help to have a cold-blooded personality that wouldn’t lose much sleep over such moral dilemmas. This may help explain why U.S. presidents appear to have an average IQ around 130, which while incredibly high, seems kind of low for people who, for many years, were arguably the most powerful person on the planet and typically attended extremely elite schools while young. In fact, an IQ of 130 is not much beyond the average Ivy League student, so U.S. presidents are probably not much brighter than the elite college kids they went to school with, despite the fact that they are light-years more successful than the average elite college grad. Although I disagree with the Lion of the Blogosphere‘s claim that high IQ is only useful for getting credentials, and after that virtually irrelevant to success, when it comes to politicians, his theory looks quite accurate.
However I suspect that high IQ is actually a huge competitive advantage, even in politics, but sociopathy is also a huge advantage, and since sociopaths have lower IQ’s, this drags down the IQ’s of elite politicians. So instead of comparing elite politicians to their typical Ivy League classmate (IQ 128), we should be comparing them to the average sociopathic Ivy League classmates (probably IQ 118, since criminal and delinquent types typically have IQ’s 10 points lower than demographically similar counterparts). So the average U.S. president (IQ 130) cognitively towers over his sociopathic elite college classmates (IQ 118), once again confirming the importance of IQ.
Of course not all U.S. presidents went to elite schools, and many most certainly are not sociopaths. Obviously I don’t know any of these men personally so I have no way of judging their true character, but President Jimmy Carter, for example, is considered a man of outstanding morality in his unwillingness to use military force and President Barack Obama has been praised as a good father and faithful husband who fought tirelessly to bring health care to working-class Americans.
It’s interesting that scholar Charles Murray said the following about Jimmy Carter:
The last thing we need are more pointy-headed intellectuals running the government. Probably the smartest president we’ve had in terms of I.Q. in the last 50 years was Jimmy Carter, and I think he is the worst president of the last 50 years.
Perhaps high IQ people make bad presidents because they’re not sociopathic enough for such a tough job.
Schizophrenic mental patient from Rob Zombie’s 2007 remake of Halloween
Halloween is coming up, so my posts are going to start getting scarier. It’s long been noted that criminals have lower IQ’s than non-criminals, and that psychotics have lower IQ than non-psychotics, so it’s only logical to assume that people who are criminally psychotic would have especially low IQ’s.
How low? Let’s begin with the fact that criminals average IQ’s 10 points lower than the non-criminal population. If we assume the United States has an average IQ of 97, then criminal Americans should have an average IQ of 87. Now it’s known that premorbid schizophrenics average IQ’s 9 points lower than matched controls. I don’t know how closely matched these matched controls are but assuming they are identical in all other ways except schizophrenia (which of course they’re not), we should expect schizophrenic criminals to have premorbid IQ’s 9 points lower than non-schizophrenic criminals. But since in rare cases, schizophrenia actually causes crime, the two variables are obviously not 100% independent, so let’s say schizophrenic criminals have pre-morbid IQ’s only 5 points lower than non-schizophrenic criminals. This implies an average IQ of 82. However once schizophrenia emerges, average IQ drops by 6 points, so their IQ’s would be reduced to 76.
For those who have never studied statistics, the non-autistic population in Western countries is said to have an average IQ of 100 and a standard deviation (SD) of 15. A standard deviation of 15 simply means that the standard amount by which most people deviate from the average is around 15 points, in other worlds, about two thirds of the non-autistic population have IQ’s from 85 to 115.
As for the autistic population, a recent study found 16% of autistic spectrum children had IQ’s below 50, while 3% had IQ’s above 115.
Assuming a normal distribution, an IQ of 116+ is 1.87 Standard Deviations (SD) above the autistic mean, and an IQ below 50 is 1 SD below the autistic mean. This suggests that autistic people have a mean IQ of 72 and an SD of 23 compared to the non-autistic population (mean 100, SD=15). In other words, while the average autistic person has a much lower IQ than the average neurotypical, the autistic population is much more cognitively variable. This resolves the paradox of why autistic people can simultaneously have a reputation for being both mentally disabled and brilliant scientists. Because, compared to neurotypicals, autistic people will be dramatically over-represented at both ends of the bell curve.
Above IQ 100
About 50% of neurotypicals have IQ’s above 100, compared to only 10% of autistic people.
Above IQ 115
About 14% of neurotypicals have IQ’s this high, compared to to only 3% of autistic people.
Above IQ 130
About 2% of neurotypicals score this high, compared to only 0.5% of autistic people
Above IQ 145
Only one in 924 neurotypicals score this high, compared to only one in 1,838 autistic people
Above IQ 160
Only about one in 42,000 neuotypicals scores this high, compared to one in 18,000 autistic people. At this level of giftedness, autistic people are actually OVER-REPRESENTED!!!!!!!!!!!
Above IQ 175
Only about one in five million neurotypicals score this high, compared to about one in 300,000 autistic people.
Above IQ 190
Only about one in 1.5 billion neurotypicals score this high, compared to about one in 14 million autistic people.
The fact that autistic people are so incredibly variable in IQ comfirms Pumpkin Person’s groundbreaking theory that autism is not actually one phenotype, but two phenotypes, that have been arbitrarily conflated by psychologists: Nerdiness (slow life history?) which causes high IQ, and executive dysfunction which causes low IQ.
Analogously, schizophrenia is probably also two phenotypes: coolness (fast life history?), which causes low IQ, and executive dysfunction, which causes even lower IQ.
Many people seem to think there’s a perfect correlation between IQ and academic achievements. So for example, if you achieve some great academic accomplishment, you are declared brilliant in perpetuity and no amount of evidence to the contrary can rob you of the title. So you often hear people make comments like “there’s no correlation between IQ and money; I know a PhD who’s on welfare” or “there’s no correlation between IQ and brain size; that famous math professor has a brain the size of an apple. Do your research!” Never once does it occur to people that the PhD welfare recipient and the apple-brained math professor, while probably both intelligent, are significantly less intelligent than normal PhDs and math professors.
Ted Kaczynski is a good example of why a more holistic view is tenable. Ted Kaczynski was clearly spectacularly accomplished academically; one of the youngest Harvard educated STEM professors in America…I’ve previously estimated that the average professor has an IQ around 130. STEM professors would probably be closer to 140. Precocious Harvard educated STEM professors should be around 150. And yet, Kaczynski ended up dirt poor, struggling to live off the land like a homeless man with no running water or electricity.
Now many people would say “obviously there’s no correlation between stratospheric IQ and money, since Kaczynski was clearly above IQ 150 and lived like a homeless man.” But Kaczynski’s IQ wasn’t anywhere near 150, and that’s the point. Kaczynski, is actually an excellent example of just how robust the IQ income correlation really is, because his IQ is not what you’d expect from the typical precocious Harvard educated STEM professor, his IQ is what you’d expect from a homeless Harvard educated former STEM professor.
Let’s say there are 600,000 homeless in America at any given time, and that Kaczynski was the most academically accomplished homeless type person in America. That would make Kaczynski about 4.7 standard deviations (SD) above the homeless mean. The correlation between IQ and academic accomplishments is about 0.65. One might expect it to be smaller in a restricted sample like the homeless, but the homeless appear to be a little more cognitively variable than the general population so perhaps not. Thus Kaczynski’s IQ should 4.7 SD (0.65) = 3.1 SD above the homeless mean. A recent study found that the WASI full-scale IQ distribution of the homeless has a mean of 84.3 and an SD of 15.7. The WASI was published in 1999, and the study was published in 2011, so we should probably subtract 3.6 points for old norms which expire at a rate of 0.3 points a year, so let’s say the homeless have a mean IQ of 81 (SD 15.7). This mean may be further inflated by the fact that the WASI was normed on the U.S. population, not on an exclusively Nordic ancestry population (as per the current convention in peer reviewed IQ articles) so for simplicity, let’s just say the homeless have a mean IQ of about 80 (SD 15.7), which makes Kaczynski’s expected IQ (3.1 SD above the homeless mean):
3.1 SD(15.7) + 80 = 129
So the most academically accomplished homeless type person in America should have an IQ around 130. As I previously discussed, Kaczynski scored a full-scale IQ of 136 on the WAIS-R, but the norms were about 15 year old at the time he was tested, making his actual IQ 132. Subtract another couple points for the fact that the WAIS-R was normed on the U.S. population, and he would be hovering around the 130 mark, exactly as simple regression would predict for a homeless Harvard educated former STEM professor, and much lower than expected for a typical precocious Harvard educated former STEM professor.
So instead of Kaczynski being an example of IQ having no, or even negative correlation with money among the brilliant or hyper-educated, he’s an example of how financial success provides useful independent information about a person’s IQ, even when they’re a precocious Harvard educated former STEM professor. This demonstrates that IQ tests really do measure intelligence, and not just narrow book smarts, because people who have spectacular book smarts, but lack the street smarts to adapt to the real world have much lower IQ’s than those who are stars in both school and life.
Some might object that Kaczynski was poor by choice, as an ideological statement, and that such adherence to principle, may demonstrate extraordinary brilliance. But the fact that money and IQ are correlated is just a statistic, and statistics don’t ask how or why. One could argue that given the endless benefits of money in modern society, choosing to be poor, when you have the option of being rich, shows even less intelligence than being unable to make money despite being hyper-motivated. Though I’m not sure I’d go that far.
