Howard Gardner argued that there was not one, but seven different intelligences. Each one can be exemplified by a historical Genius who changed the trajectory of history:

Logical Mathematical

Newton, revolutionized math, physics and astronomy

Verbal

Shakespeare: Wrote beautiful things

Spatial

Wright Brothers: Turned humanity into a flying species

Social

Oprah: Led millions of sexual abuse survivors to recovery, mainstreamed discussion of taboo topics like gays, got millions of couch potatoes to read literature, and put a black family in the White House

Intrapersonal

Buddha: helped us find inner peace

Musical

Mozart: created the world’s greatest music

Bodily-kinesthetic

Bruce Lee: despite being short and slim and coming from a population with slower movement speed, was able to physically defeat anyone on Earth.

One intelligence or many?

If there are seven different intelligences, why do IQ tests mostly just measure the first three (or four) with some only measuring the first?

As my high school Chemistry teacher told me so many years ago, “when you talk about intelligence, there are so many different parts to it…if you want a single umbrella to cover all of intelligence” (stretching out his arms to convey the vastness of it, “then it’s the ability to adapt: to take whatever situation you’re in, and turn it around to your advantage. That’s really what intelligence is”

Those words are burned into my brain.

So it’s mostly the first half of these intelligences (logical, verbal, spatial and perhaps social) that have helped us adapt as a species and turned the World to our advantage. Without the logical ability to create science, the spatial ability to create technological and the verbal/socal ability to communicate, we’d still be in the stone age. The other intelligences are useful, but perhaps not as much as the first three or four, so it’s not surprising that the Wechsler IQ tests have empathized logical-mathematical ability (Arithmetic, Matrix Reasoning, Figure Weights), verbal ability (Vocabulary, Similarities), spatial ability (Block Design, Object Assembly) , social understanding (Comprehension, Picture Arrangement). Only one subtest measures bodily-kinesththetic (Digit-Symbol), and none have ever measured intrapersonal or musical talents.

And notice that the most useful abilities seem to load most on the general factor of all cognitive abilities known as g. Perhaps g is simply how much of the brain an ability uses, and the abilities using more of the brain must have been useful or expensive brain mass would not have evolved to support them.

And the most g loaded ability of all is abstract reasoning and that’s also the most adaptable because the abstract transcends the specific context and allows you to solve a problem in universal form. Knowing one apple plus one apple equal two apples allows you to thrive in the orchard. but knowing x + y = z allowed us to leave our African Garden of Eden and reach for the starts.

If you’re good at math, then you are good at logic, and it you’re good at logic, you can be good at almost everything, because the universe is intrinsically logical.

Commenter Ray Penver writes:

Hi, PP! It’s me again
I wonder what would be your estimation of Isaac Newton’s IQ.
I know quite a bit about his life.
He’s considered the best physicist and scientist ever, one of the best mathematicians ever and one of the most influential people, too.
So, what do you think?

Newton’s IQ is fascinating because not only is he considered the best physicist of all time, but according to Michael Hart’s book The 100, the second most influential person of all time; though one led to the other. These aren’t independent achievements,

So what was his IQ?

According to this source, 60.5 billion people have lived from 1 AD to 2011. Let’s say 16% were white. Assuming Newton was the best physicist to ever live, he would have at the very least been at the one in 9.68 billion level among whites, which is +6.33 standard deviations (SD) on a normalized curve.

However great achievement requires more than just ability. It also helps to have 10,000 hours of practice, among other things. Ability seems to explain 66%  to 70% of the variance in various cognitive performance, suggesting ability correlates 0.82 with performance.

So if Newton were +6.33 SD in physics performance, we’d expect him to be 0.82(+6.33) = +5.19 SD in physics ability.

How much does physics ability correlate with IQ? The math section of the WIAT correlates 0.84 with WAIS-IV full-scale IQ, so if Newton were +5.19 SD in physics ability, I’d expect him to be 0.84(+5.19 SD) = +4.4 SD in IQ. In other words, I’d expect him to have scored IQ 166 (white norms) on a random test normed in his day.

To appreciate how high that is, young white American men have an average height of 5’10.1″ (SD = 2.94″) so an IQ of 166 is the height equivalent of being 6’11”. Both are +4.4 SD.

So just as we might expect the greatest basketball player of all time to be 6’11”, we’d expect the greatest physicist of all time to be IQ 166.

To those who think even IQ 166 is not high enough for a mind as great as Newton, I point to examples of other great minds who scored much lower on IQ tests such as Ted Kaczynski in adulthood or Garry Kasparov. For those who say the tests weren’t valid measures of their intelligence, I say IQ is an imperfect science. An IQ score is simply one’s performance on highly g loaded psychometric tasks not a direct measure of neurological functioning, so occasionally it will give highly flawed results. IQ 166 is simply my best guess of how Newton would have scored on a randomly selected high ceiling IQ test considered valid in his time and place, not necessarily a prediction of his actual intelligence.

IQ stands for intelligence quotient because originally IQ was calculated as the ratio of mental age to chronological age, so if you were a six-year-old who cognitively functioned like the average six-year-old, you had an IQ of 100, because you were functioning at 100% of your chronological age. By contrast if you were a six-year-old who was functioning like a four-year-old, your IQ was 66, because your development was only 66% as fast as it should be, and you were sent to what were then called EMR classes.

This was a beautifully elegant concept but there were a few problems. The first is all of us are 0.75 years older than we think we are since we grew in the womb for 9 months. The age ratio method would have made more sense if they had added 0.75 to both the chronological and mental ages and I suspect the distribution would have been more normal.

The other problem is cognitive growth is not linear function of age throughout the entire maturation process.

“Some guy” writes:

Does it really matter if it’s not linear though? If someone scores as the average 10 year-old then it indicates they have the drawing IQ of a 10-year old, which seems more useful than a subjective number.

What’s more useful information about a man’s height? That he’s as tall as the average 10-year-old, or that he’s 1.3 feet shorter than the average man. Both are useful, but the advantage of creating a scale that is independent of age is that it has a much higher ceiling. On the old Stanford-Binet, scores stopped increasing after age 15, so how do you assign a mental age to someone who is smarter than the average 15-year-old?

The old Stanford-Binet got around this problem by arbitrarily extending the mental age scale beyond 15, so Marilyn vos Savant was able to claim an IQ of 228, because she scored a mental age of 22.8 at age 10, even though there was no such thing as a mental age of 22.8 on a test where mental growth peaks at 15.

This makes about as much sense as telling a 19-year-old seven-footer they have a height age of 92, and therefore a Height Quotient of 484, after all the average male height only increases by 0.2 inches from 19 to 20, so if height didn’t plateau, at that rate it would take the average man until his 90s to reach seven feet.

“Some guy” continues:

Presumably they still used this system to see if people scored averagely for their age, but had to first to figure out what the average for each age was anyway.

A related question: Is the mental age concept still applicable to modern IQ tests even though they’re not based on it? Let’s say 10-year old scores 130 on the WAIS. 2 SD above the mean on a 16 SD mental age test would be 132. Can that child be assumed to have the same IQ as the average 13.2 year old?

Put it this way. If a ten-year-old scored like an average 13-year-old on every subtest of the WISC-R, he’d get a full-scale IQ of 126, which is similar to the 130 you’d expect from the age ratio formula. On the other hand if a 10-year-old scored like a 15-year-old on the WISC-R, he’d get a full-scale IQ of 134, which is much less than the 150 you’d expect from age ratios.

And yet if a six-year-old scores like a nine-year-old on the WISC-R he gets a full-scale IQ of 143. So the same ratio IQ equates to different deviation IQs depending on what age it’s obtained (or what test it’s obtained on) which makes it a problematic index.

It probably agrees most with deviation IQ when both the chronological and mental age are no lower than 4 and no higher than 12, since that’s probably the most linear developmental period.

Back in 2016, commenter Recuring cited the following quote:

We of the Study of Mathematically Precocious Youth (SMPY) at Johns Hopkins have discovered, chiefly by testing able 12-year-olds, that when the examinee’s SAT-M score vastly exceeds his or her SAT-V score the youth is almost certain to score high on a difficult test of nonverbal reasoning ability such as the Advanced Form of the Raven Progressive Matrices, often higher than a high-M high-V examinee does. To test this out, on 6 May 1985 I administered to Terry the RPM-Advanced, an untimed test. He completed its 36 8-option items in about 45 minutes. Whereas the average British university student scores 21, Terry scored 32. He did not miss any of the last, most difficult, 4 items. Also, when told which 4 items he had not answered correctly, he was quickly able to find the correct response to each. Few of SMPY’s ablest protégés, members of its “700-800 on SAT-M Before Age 13″ group, could do as well. 

http://www.davidsongifted.org/Search-Database/entry/A10116

I found the norms for this test (hat-tip to commenter Rahul for telling me they’re online) so I was finally able to complete part 3 of this series (three years after part 2).

For UK 10-year-olds, the 5th percentile (IQ 75) is a raw score of 1, while the 95th percentile (IQ 125) is a raw score of 15. If we assume raw scores are roughly normally distributed, we can crudely estimate that a 14 point gap in raw score equates to a 50 point IQ gap, and thus Terry’s score of 32, which is 24 points above the median raw score of 8, would thus be 86 points above the median IQ of 100, or IQ 186 (UK norms).

Some might argue that we should deduct a few points for the Flynn effect since the UK norms were six years old, however my sense is that the Flynn effect has been wildly exaggerated. For example, on the WAIS-III Matrix Reasoning subtest, average raw scores are identical for all ages from 18 to 34 and on the Advanced Progressive Matrices U.S. white norms (since it was normed in lily-white Iowa), there’s no change in raw scores from age 20 to 30:

In honor of Super Bowl Sunday, I thought I’d ask whether physical abilities have a general factor (g), the same way cognitive abilities do? For those who don’t know, Charles Spearman famously discovered that all cognitive abilities are positively correlated, suggesting they all are influenced by some general ability, and thus the most efficient way to measure someone’s overall cognition was to test the most g loaded abilities (since these best predict all other abilities).

The existence of a physical g factor would be useful (though not necessary) for assigning people an AQ (athletic quotient), the same way IQ tests assign folks an IQ (intelligence quotient).

Cognitive and physical abilities are both forms of voluntary goal directed behaviors that can be objectively graded on a scale of proficiency, but because cognitive abilities are more prestigious (at least after high school), we increasingly see athletes trying to claim their abilities are mental instead of physical. And so we have commenters claiming that weight lifting requires not just physical strength, but coordination, and terms like kinesthetic intelligence have emerged in the literature.

We all have our biases, which is why I love factor analysis, which allows us to objectively decide what category or sub-category different abilities fall into. Factor analysis is a technique where you look at the intercorrelation between a large number of traits, and notice that some intercorrelate better than others, allowing you to infer sources of variance that are common to some traits but not others, allowing you to group traits into different clusters.

When you control for these common sources of variance, you find that some traits still intercorrelate better than others, allowing you you to infer higher sources of common variance. This allows for a hiearchy of categories and sub-categories that is wholly objective, requiring no judgement or decision on anyone’s part, and yet still agrees with common sense.

As the late Arthur Jensen noted, when you factor analyze hundreds of clothing measurements from every body part dimension imaginable, you find almost all of the variance can be explained by just three factors: general body size, body length, and body width analogous to how every location on Earth can be explained by just three data points (latitude, longitude, and altitude).

When we give people an extremely diverse series of tasks, we find that most tasks that are commonly thought of as physical (running, jumping, lifting) are more positively correlated with each other than with tasks commonly thought of as mental (repeating numbers, defining words, solving jig-saw puzzles). To be sure, there are certain hybrid abilities that load equally on both domains.

When the 11 subtests on the WAIS-R were factor analyzed, it turned out that even though David Wechsler thought he was measuring 11 different parts of intelligence, most of the variance in scores could be explained by just four factors: general intelligence, verbal knowledge, spatial ability, and short-term memory.

Similarly, when ten different physical tests were factor-analyzed, it was found that most of the variance could be explained by just five factors: general athleticism, strength, running ability, coordination, and balance. I find it interesting that measures of physical strength (hand-grip, chinning) have negative loadings on both coordination and balance, suggesting an evolutionary trade-off between muscle and control as we marched up the evolutionary tree.

It’s interesting to note that just as vocabulary was the single best measure of cognitive g in the cognitive battery, 100-yard dash was the single best measure of athletic g in the athletic battery. So just as people who score at the one in a billion level (relative to Western norms) on g loaded cognitive tests are said to have IQs of 190+, people who would score at the one in a billion level on the 100-yard dash can claim an AQ of 190+. That doesn’t mean their athletic g is truly at the one in a billion level (even the 100-yard dash is an imperfect measure of athletic g) but it’s about as close to a perfect measure of athletic g as the best IQ tests are to perfect measures of cognitive g.

Of course the best measure of athleticism would be to give people the full battery of physical tests and calculate the composite score, but if you wanted a short-form, you would just take the 100-yard dash, just like when psychologists wanted a short-form for IQ, they would just test Vocabulary, though more recent research suggests that g loading of Vocabulary has declined or was never as high as once thought.

Which brings us to another key point: The factor structure of any correlation matrix is sensitive to what tests you include, so skeptics might want to see a similar factor structure replicated in several diverse random selections of tests before accepting the factors and their loadings on various tests.

Charles Murray was recently interviewed by Bill Kristol (who made my annual list of the 100 most influential living people of all time). Murray himself might one day make the list for the enormous impact his 1984 book Losing Ground had on public policy.

I could listen to Murray talk for hours. The man exudes gravitas.

Kristol worships Murray, once calling him America’s leading living social scientist. Despite being a lightning rod on college campuses, Murray is whined and dined by the elite.

[note from PP, feb 4, 2019: an earlier version of this article contained a spelling mistake that has since been corrected]

According to wikipedia, 100% of the fastest twenty 100 meter runners of all time are blacks, and 65% of the World’s best ping-pong players are East Asian. This fits J.P. Ruston’s theory that blacks and East Asians are at opposite extremes of an evolutionary trade-off, with Caucasoids in the middle (though closer to East Asians), consistent with the time period each race branched off the human evolutionary tree (Blacks first, Caucasoids second, Mongoloids last).