Estimating the IQs of Billy & Ricky Chapman


Adult Billy Chapman (played by Robert Brian Wilson)

Commenter Mikey Blaze wanted me to write more about horror and it would not be Christmas without mentioning  Silent Night Deadly Night (1984), one of my favorite films of all time (not to be confused with the 2012 film Silent Night).

The film tells the story of Billy Chapman, a little boy who sees his parents killed by  a man dressed as Santa, and when forced by his boss to dress up as Santa on Christmas, goes on a killing spree at the age of 18.

At the start of the film we see five-year-old Billy reading The Night Before Christmas, suggesting the reading level of about a six-year-old.  Since his reading age is 120% his chronological age, this implies an IQ of 120,  at least at the age of five.

His IQ might have gone down after that because he spent the next 13 years being raised in an orphanage, however under the strict discipline of the terrifying Mother Superior, I suspect he got a good education (even though his emotional development was further scarred).  Not that I think education can much affect real intelligence, but it can bias test scores.

Further evidence of Billy’s high IQ is he has the visual-motor ability to kill his coworker with a bow and arrow despite perhaps never using one before, and he has the lateral thinking to kill a naked woman by pinning her to the horns of a reindeer.

On the other hand, Billy’s childlike morality (killing people for having sex because sex is naughty) and extremely short life-span (shot by police at 18) show low IQ, but perhaps these can be excused, given his extreme childhood trauma.

But  Billy may have also inherited low IQ DNA from his psychotic grandpa.  Perhaps grandpa was schizophrenic and Billy would become so too.

Research states:

meta-analyses show an average premorbid 8-point IQ deficit (0.50 SD) among those who later develop schizophrenia but a 14-21 point IQ deficit (0.90-1.40 SD) among first-episode and chronic schizophrenia patients

In other words, IQ drops about 10 points as one becomes psychotic, so while Billy’s childhood IQ may have been 120, his adult IQ was perhaps 110. Still smarter than 75% of white Americans his age.

In Silent Night Deadly Night II, Billy’s little brother Ricky takes over as the killer.


Ricky Chapman played by Eric Freeman

Given Ricky’s bizarre facial expressions and muscular physique, I suspect he was less intelligent than Billy.  Siblings share 50% of their DNA and their IQs correlate +0.5, so Ricky likely regressed to the mean in IQ from Billy’s 110 IQ.  But not to the IQ 100 mean of the general white population, but the IQ 73 mean of the criminally insane white population.

Thus Ricki’s expected IQ is:

(Billy’s IQ – criminally insane mean)(sibling IQ correlation) + criminally insane mean

(110 – 73)(0.5) + 73 =92

An IQ of 92 would put Ricki Chapman in the bottom 30% of the white Americans his age, explaining why he was the dumbest of the three characters here:




Answering reader questions part 2

A reader sent me the following email:

“I’ve always wondered if a person with strong drawing (or painting) abilities would score well on perceptual reasoning. Is there a correlation? If so is it a very strong and clear correlation?”

I don’t think there is. A study of prodigies documents a case of a painting prodigy who scored IQ 88 (U.S. norms) in spatial ability (bottom fifth of Americans her age)

At the time of testing, prodigy seven, a self-taught painter, was nineteen years of age. Although she had been interested in arts and crafts for as long as she could remember, she did not begin to paint until she was 13 years old. She said she was inspired by a young art prodigy she saw on television. After just eighteen months of painting, the prodigy won the National Gold Key award, the most prestigious art award given to high school students, at the age of 15. She was one of 50 recipients of the award across the country. At nineteen, her work is selling for thousands of dollars and is displayed in prestigious art museums around the world.

Testing results

Total IQ Score= 112; Fluid reasoning= 100; Knowledge= 128; Quantitative Reasoning= 100; Visual Spatial Abilities= 88; Working Memory= 138

It seems artistic ability requires certain special abilities, like being able to differentiate hues that have little to do with the perceptual reasoning tasks on tests like the WAIS or the Binet.
Another reader sent me the following email:

“So I’ve stumbled across one of your articles in your blog, and in it you said that WAIS IV has correlation with g of 0.9 (if I’m not mistaken?). Also somewhere in the comments I’ve read that Raven’s Advanced Progressive Matrices has correlation with g of 0.8 (if I’m not mistaken?).

Where do these numbers come from?
Also if these are correct, does that mean that WAIS IV should give you a better representation of your ‘overall’ intelligence?
So to clarify, does higher g-loading mean that the test is better approximation for your ‘true’ IQ?
Thanks in advance!”
The 0.9 figure for the WAIS-R (and by inference other editions) comes from Jensen.  He mentions it in his landmark book Bias in Mental Testing.
The 0.8+ g loading often cited for the Raven is probably too high (at least in today’s population).

In a 2017 study by Dimitri van der Lindena, Curtis S. Dunkelb, Guy Madison, the Raven was found to have a g loading of 0.609 in 900 American healthy young adults.


However in my opinion this sample likely suffered from range restriction, and the actual g loading of the Raven in the general U.S. population is about 0.7.  That’s roughly the g loading of the Matrix Reasoning subtest on the WAIS-IV in an extremely representative sample of Americans.

g is simply whatever is causing all cognitive abilities ever discovered to positively correlate in nationally representative samples, so the more an ability loads on g, the more predictive it is of one’s overall cognition (at least in the biologically normal population). There’s a lot more to intelligence and IQ than just g but g‘s perhaps the most scientifically precise measure of intelligence we have.

Answering reader questions part #1

As a Christmas gift to my readers, Santa Pumpkin is going to answer some questions his readers have been asking.  I’ll start with Thinking Mouse, since he asked his question in the comment section:

What I want to figure out is how large of an percentage of all genomically high iq people are in the upper class, within the third world. Make that into a ratio to see the correlation between genomic iq and wealth within the third world. From that we could also guess the correlation between wealth and iq by comparing it to the west on the same traits.

The best we can do is try to estimate this correlation is the First World and assume it’s the same in the Third World.

The correlation between IQ and self-made lifetime income in the U.S. is about 0.48, and the correlation between IQ and inherited wealth would be about 0.22.  So lumping the self-made rich and the trust-fund babies together, the correlation between wealth and IQ in the U.S. would be about 0.35.

Now to find the correlation between wealth and genomic IQ, we need to divide the correlation between IQ wealth by the correlation between IQ and genomic IQ.  If one takes twin studies at face value, IQ has a heritability of about 0.75, implying a genotype-phenotype correlation of 0.87 (at least among the adopted).

But as Mug of Pee and Swank have noted, a major problem with twin studies all done in the same or similar countries is reaction norms.  In other words, genome A may score higher than genome B in all U.S. environments, not because genome A causes higher IQ per se, but causes some other IQ enhancing behavior (i.e. eating brain food like fish), but if both genomes were reared in the Third World (where fish is too expensive) genome A might have a lower IQ phenotype than genome B.

One way to determine the actual causal correlation between IQ and DNA is to create a single test that is highly g loaded in the worldwide population and have an international genotyped sample of a million people take that test, and then have machine learning identify the genetic variants that best predict IQ among these culturally diverse people, holding the Human Development Index of each genome’s country constant.

Of course the genomic predictor the computer spits out will underestimate the true within-country causal correlation between IQ and DNA because perhaps only 75% of IQ is caused by common additive genetic variants while the remaining is caused by rare and/or non-additive genomic effects which are hard to identify.  But mathematically adjusting for this fact might give a good estimate (assuming IQ has the same genomic architecture in all countries).


Elites secretly believe in HBD

Most elite Americans publicly deny HBD.  Some people think this is because HBD is pseudoscience, and elites are smart enough to realize that.  Other people, like Lion of the Blogosphere, think it’s because even smart people are irrational, and just believe whatever their peers believe.  Others, like  commenter “Mug of Pee” think only the most brainwashed people are selected to become elites (though Mug of Pee agrees with their HBD denial, he thinks elites are brainwashed in other areas).

In my opinion, the truth is much simpler:  elites deny HBD because they are LYING.

In the past I mentioned the below video (go to the 57 minute mark), where Charles Murray claims the fiercest critics of his book The Bell Curve were privately fans, and we the public would be stunned to learn who the fans are (apparently some of the biggest liberals in academia).

This shows there’s a large population of elites who will not only publicly deny HBD despite secretly believing it, but go out of their way to attack HBDers.

Now you might say Murray is an HBDer, why should we believe him when he says “liberal” academics secretly believe in HBD?

But his claim is corroborated by eminent HBD denier Jared Diamond (47:52 mark in below video) who says when he secretly asks members of the elite (a cabinet minister, a high tech leader, many university professors), they shamefully confess to being HBDers.

It’s not just white elites and it’s not just HBD they lie about.  Many were shocked that politically correct establishment darling Joy Reid secretly had some controversial views when it comes to Israel.

So contra Mug of Pee, elites are not selected based on what they actually believe; rather most humans are liars, and high IQ people know which lies will get them ahead (though the super-duper high IQ may refuse to lie because of more developed morals).

The Pope is not necessarily Catholic.


Why are the leaders of Western countries so pro-immigration?

Historically, humans have been very tribal creatures,  caring only about their group, so it’s interesting to ask why leaders of Western countries have been so generous in their immigration policy over the last half-century.   And by leaders I mean anyone who has influence over the country, whether political, economic, academic, or pop-cultural. I am going to list several theories and let my brilliant readers decide.

This question, if answered honestly, might make a good test of social intelligence and general knowledge,  but I’m not wise enough to know if my answers are the correct ones, so in the comment section, let me know which combination of these theories, if any, played the biggest role in mass immigration to the West and which of these theories are just nutty.

Theory 1:  Immigration distracts from economic inequality

This theory is advanced by commenter “Mug of Pee” and also pushed by Noam Chomsky.   The idea is that if you have lots of immigrants,  group conflict will be racial instead of economic,  so the rich will not have to worry about people resenting their wealth because folks are too busy resenting other races.  Social injustice will be seen through a racial lens instead of an economic one, so privileged races get vilified while privileged classes avoid scrutiny.

Theory 2:  Immigrants are good for business

Commenter pumpkinhead writes: “The corporate elites who broadly speaking transcend nationality or ethnicity want a global world in order to expand their corporate empires and allow for easier movement of goods, better friction-less access to resources and cheap labor.”

Theory 3:  Immigration is a way for empires to course correct

Commenter pumpkinhead writes:  ” Countless civilizations have had to contend with assimilating various people of different descent… Just try to envision what it would be like in Ancient Rome, or Hellenistic Greece with their conquest of much of western Asia. When the British decided to dissolve the British empire they too decided to make amends for their past transgressions by making concessions to the people they governed around the world. Part of that was opening the doors to some of those minorities into Britain. IMO leftist ideologies are strongest right after the apex of interventionism war or imperialistic behaviour. It is a course correcting mechanism that many nations impose on themselves in order to self correct. If handled properly they might be better off for it but if not it can destroy them… ”

Theory 4:  Immigration to the West allows diaspora minorities to thrive

This  controversial theory, promoted by Kevin MacDonald, argues that over the 20th century,  a  small subset of Ashekenzi Jews used their high IQs, wealth, and influence to lobby for more immigration because in countries where everyone is blond, blue eyed and Christian,  Jews are “other”, while in multi-racial countries, Jews blend into the white establishment and resentment shifts towards more conspicuous minorities, especially Muslims (which is convenient for Israel which is often in conflict with her Muslim neighbors).

Theory 5:  Northwest Europeans are genetically nicer

This theory,, also advanced by Kevin MacDonald argues that Northwestern Europeans are especially kind to strangers because they partly evolved in the European ice age where you had to cooperate.  A variant of this theory, advanced by HBD Chick, is that  Northwestern Europeans are especially welcoming because they had less cousin marriage, which makes them less clannish.

Theory 6: People are more pro-immigration because we’re getting smarter

Studies show that higher IQ people are less racist, and since IQ went way up over the 20th century (the Flynn effect), I argued that this might be one of the reasons that mass immigration became more accepted

Theory 7: People are more more pro-immigration because of harmful mutations

Because of medical advances, harmful mutations that would have normally been weeded out by natural selection are now remaining in the population.  Proponents of dysgenic theory argue that all these mutations have made people less genetically fit, so they no longer care about reproducing or protecting their ethnic interests.

Putting human mini-brains in mice

Thanks to better nutrition and disease reduction increasing human brain size and intelligence (the Flynn effect) we are seeing some of the greatest technological advances since the industrial revolution:

At the annual meeting of the Society for Neuroscience starting November 11 in Washington D.C., two teams of scientists plan to present previously unpublished research on the unexpected interaction between human mini-brains and their rat and mouse hosts. “In the new papers, according to STAT, scientists will report that the organoids survived for extended periods of time — two months in one case — and even connected to lab animals’ circulatory and nervous systems, transferring blood and nerve signals between the host animal and the implanted human cells,” reports Inverse. “This is an unprecedented advancement for mini-brain research.”

The next step is to get mini-brains from a large sample of people of known IQs or SAT scores and then test the intelligence of the mice that carry them.  Would there be a positive correlation between the SAT score of the person from which the mini-brain is derived and how fast the mouse can run through the maze? If so, how high would the correlation be?

Maybe a smart person would get stuck with a dumb mouse, thus lowering the correlation, so each person could produce dozens of mini-brains for dozens of different mice allowing individual mice differences to cancel out.  Would the group of mice implanted with the high SAT person’s mini-brains average much faster maze times than the group of mice derived from the low SAT person’s mini-brains?

If so it would prove that the normal variation in human intelligence is not just correlated with DNA, but largely caused by independent genetic effects, debunking those who invoke reaction norms.


Answering reader mail

A reader sent the following email:

Good evening, sir!   I’ve been enjoying your blog and have a rather random question that I’d love to hear you weigh in on.  I recently took a self-scoring IQ test from a book written by the late Victor Serebriakoff.   I am curious as to how accurate the scores are.  The publishing date was 1996 so I’m wondering how much this would distort the results.  A number of online reviewers claim the score they received on this test is identical to the score they received on their WAIS.  Would the scores necessarily be grossly inflated?  Or could they be relatively accurate?  The test consists of 300 questions with subtests for verbal, spatial, and numbers.  Just curious to hear your take on it.  Thanks for taking the trouble to read this meandering email!

I don’t have a copy of this test so all I can do is provide a meandering speculative reply:

Given Victor’s credentials as the head of Mensa, combined with the fact that the test had 300 questions of diverse type,  I would guess it’s a very valid measure of intelligence.

But whether the scores are inflated is hard to say.  I’ve seen several self-scoring IQ books in my life and none of them have ever explained how they converted the raw scores into IQs.  And in some cases, they don’t even adjust for age, treating all adults as a single age group.

If Victor had done a quality job norming the test, then I’d expect him to have discussed it in the book.  If he didn’t, then he may have just used a convenience sample (friends, acquaintances) and since he’s a high IQ man, his circle of acquaintances are likely above average.  If so, the test might actually underestimate your intelligence.

On the other hand,  the test is over 20 years old, so the Flynn effect might have caused your score to become inflated by as much as 6 points.  Although, when tests are normed on the entire country (instead of just the white population) demographic changes can negate or even reverse the Flynn effect.

I also wonder how this test arrived at overall IQ scores since you say it measured several cognitive domains.  If it merely averaged your scores on all three domains, it may have underestimated your overall IQ,  since for example only 5% of the population maybe smart enough to average in the top 10% across three different abilities, so such people are perhaps in the top 5% (IQ 125+) even though they average in the top 10% (IQ 120+).

A reader sent the following questions by email:

Also, what other traits determine the variation in academic achievement. Achievement and IQ only have a .5 correlation.

Just a hypothetical- what if you come across a vocab word or an information subtest fact a couple days after the test?…

Depends what you mean by academic achievement.  If you mean scores on an academic achievement test (which measures your total academic knowledge), the correlation is much higher than 0.5 in the general U.S. population.

If you mean the correlation between IQ and academic success (i.e. school grades, highest level of schooling) then it’s about 0.57 in the general U.S. population,  although it used to be 0.7.

The other major trait that predicts academic success is conscientiousness.

Beyond those two major traits are probably a a whole bunch of minor traits, which on their their own explain very little, but collectively explain quite a bit.  These might be things like physical heath, conformity, how much your teachers like you, how much you like school, whether you’re a night person or a day person (as commenter Mug of Pee once mentioned) etc.

It’s also worth noting that verbal IQ better predicts academic success than performance IQ, even holding general intelligence constant.

Of course the term “predict” might be a bit of a misnomer.  Correlation != causation.  There’s evidence that staying in school longer might raise IQ (though it’s unclear if it’s actually raising intelligence itself)

As for your second question, what you know outside the testing room is irrelevant.  As David Wechsler noted, the tests are designed to measure your intelligence under a fixed set of standardized conditions.  Once you leave that controlled environment, you’ve left the test.

A reader sent the following question by email:

Pumpkin, do most people on processing speed tests go as fast as they possibly can?

Yes, I think they do.  Although the term processing speed is a bit of a misnomer.  These subtests have among the weakest correlation with chronometric ability.  Ironically, it’s the untimed power tests that often enjoy the highest correlation with chronometric ability.  People in the field are very familiar with the slow looking nerd who is brilliant at solving really deep problems.  Such individuals do relatively poorly on tests of psychometric speed, but extremely well on tests of chronometric speed.

Psychometric speed tests are poor tests of general intelligence, but they seem good for measuring the intelligence of otherwise smart people who just can’t adapt.

I’ve had a couple friends who did well on most g loaded tests, yet I did not consider these friends smart because they couldn’t adapt  situations to their advantage in real life.  Both of these friends did extremely poorly on the processing speed subtest of the WISC-R.



How do you prove an accomplished person does not have a 120+ IQ?

A reader sent me the following email:

In the article: ‘Do you need to be genius to be genius’ you said
greatness is not an exclusively property of 120+ IQ people. I think it
is. All the great people in the world have 120 or more. Even
subjective iq measurements of those among them whose IQ scores arent
known, have come out to 120 + iq…

I can think of many examples of eminent people who scored below 120 on an IQ type test:

JFK tested at 119

Bill Cosby’s SAT score equated to IQ 84 (though as a child he aced a formal IQ test)

JD Salinger scored IQ 104

Howard Stern’s SAT scores equated to IQ 115

Muhammad Ali’s army test score equated to IQ 85

Condoleeza Rice was told she wasn’t college material based on her PSAT scores (though she aced an IQ test as a toddler)

Rudy Giuliani’s 1073 SAT score likely equated to IQ 119 in his day


The problem is, any time you cite these, people immediately call the IQ score into question.  The score is dismissed because the person was tested during childhood, or the test did not measure the cognitive domains the person excels in, or the person wasn’t trying or had a learning disability preventing him from understanding the instructions etc.

In some cases these explanations are valid, but if no amount of evidence can convince you that an accomplished person doesn’t have a 120+ IQ, then  your view is unfalsifiable and thus unscientific.

There are four main reasons people think all accomplished people have 120+ IQs:

They don’t realize how high IQ 120 is

An IQ of 120+ means you’re smarter than 90% of (white) Americans your age.  A young adult who is taller than 90% of white Americans his age is 6’1″+ which is considered a very respectable height and yet an equally rare IQ is considered chopped liver.

They don’t appreciate IQ inflation

Because people  take many IQ tests that often give wildly different scores and then cherry-pick their best scores, an IQ below 120 sounds low to them.  Also, because there are so many elite colleges and high IQ societies accepting scores from so many different tests, it feels like there are so many communities with average IQs above 140, when in reality, many of these groups would regress to the 120s if given a test not used to select them.  Part of what admission tests select for is scoring higher on the admission test than you score on other intelligence tests.

They overvalue intelligence

Intelligence might be the single most important trait, but it’s dwarfed by the totality of other traits.  IQ is probably no more important to most types of success than height is to fighting ability.  On average the best boxers in the world will be well above six feet, but occasionally men of average height will dominate (i.e. Mike Tyson).  Even in fields where height is overwhelmingly important (i.e. basketball), you’ll find the occasional super-short guy (“Muggsy” Bogues), so even at the top of fields as IQ loaded as science, I’d expect a few not-smart people.

They don’t appreciate the bivariate normal distribution

Everyone knows that a super failure can have a super high IQ, but so many deny that a super achiever can have a super low IQ.  But the correlation between IQ and achievement is only meaningful if you believe in the bivariate normal distribution which means that for every high IQ person who is low on achievement, there must be a high achievement person who is low in IQ.


Of course these statistical models are just abstractions that are never perfectly observed in nature so things are not quite as symmetrical as the graph implies,  but they’re pretty good approximations.

People have no trouble accepting that height can dramatically overpredict weight and weight can dramatically overpredict height, yet when it comes to IQ and achievement, they think only the former can greatly overpredict the latter and not vice versa.