Comments on Chauncey Tinker’s Intelligence, Concentration, and IQ Tests

A while back, Chauncey Tinker wrote a post on Intelligence, Concentration, and IQ Tests:

I do not believe that IQ tests measure intelligence. Rather I believe that they measure a combination of intelligence, learning and concentration at a particular point in time. …

You may wish to read the whole thing there.

The short response is that I basically agree with the bit quoted, and I suspect that virtually everyone who takes IQ tests seriously does as well. We all know that if you come into an IQ test hungover, sick, and desperately needing to pee, you’ll do worse than if you’re well-rested, well-fed, and feeling fine.

That time I fell asleep during finals?

Not so good.

Folks who study IQ for a living, like the famous Flynn, believe that environmental effects like the elimination of leaded gasoline and general improvements in nutrition have raised average IQ scores over the past century or two. (Which I agree seems pretty likely.)

The ability to sit still and concentrate is especially variable in small children–little boys are especially notorious for preferring to run and play instead of sit at a desk and solve problems. And while real IQ tests (as opposed to the SAT) have been designed not to hinge on whether or not a student has learned a particular word or fact, the effects of environmental “enrichment” such as better schools or high-IQ adoptive parents do show up in children’s test scores–but fade away as children grow up.

There’s a very sensible reason for this. I am reminded here of an experiment I read about some years ago: infants (probably about one year old) were divided into two groups, and one group was taught how to climb the stairs. Six months later, the special-instruction group was still better at stair-climbing than the no-instruction group. But two years later, both groups of children were equally skilled at stair-climbing.

There is only so good anyone will ever get at stair-climbing, after all, and after two years of practice, everyone is about equally talented.

The sensible conclusion is that we should never evaluate an entire person based on just one IQ test result (especially in childhood.)

The mistake some people (not Chuancey Tinker) make is to jump from “IQ tests are not 100% reliable” to “IQ tests are meaningless.” Life is complicated, and people like to sort it into neat little packages. Friend or foe, right or wrong. And while single IQ test is insufficient to judge an entire person, the results of multiple IQ tests are fairly reliable–and if we aggregate our results over multiple people, we get even better results.

As with all data, more tests + more people => random incorrect data matters less.

I think the “IQ tests are meaningless” crowd is operating under the assumption that IQ scholars are actually dumb enough to blindly judge an entire person based on a single childhood test. (Dealing with this strawman becomes endlessly annoying.)

Like all data, the more the merrier:

Thanks to Jayman
Thanks to Jayman

So this complicated looking graph shows us the effects of different factors on IQ scores over time, using several different data sets (mostly twins studies.)

At 5 years old, “genetic” factors, (the diamond and thick lines) are less important than “shared environment.” Shared environment=parenting and teachers.

That is, at the age of 5, a pair of identical twins who were adopted by two different families will have IQ scores that look more like their adoptive parents’ IQ scores than their genetic relatives’ IQ scores. Like the babies taught to climb stairs before their peers, the kids whose parents have been working hard to teach them their ABCs score better than kids whose parents haven’t.

By the age of 7, however, this parenting effect has become less important than genetics. This means that those adopted kids are now starting to have IQ scores more similar to their biological relatives than to their adoptive relatives. Like the kids from the stair-climbing experiment, their scores are now more based on their genetic abilities (some kids have better balance and coordination, resulting in better stair-climbing) than on whatever their parents are doing with them.

By the age of 12, the effects of parenting drop to around 0. At this point, it’s all up to the kid.

Of course, adoption studies are not perfect–adoptive parents are not randomly selected and have to go through various hoops to prove that they will be decent parents, and so tend not to be the kinds of people who lock their children in closets or refuse to feed them. I am sure this kind of parenting does terrible things to IQ, but there is no ethical way to design a randomized study to test them. Thankfully, the % of children subject to such abysmal parenting is very low. Within the normal range of parenting practices, parenting doesn’t appear to have much (if any) effect on adult IQ.

The point of all this is that what I think Chauncey means by “learning,” that is, advantages some students have over others because they’ve learned a particular fact or method before the others do, does appear to have an effect on childhood IQ scores, but this effect fades with age.

I think Pumpkin Person is fond of saying that life is the ultimate IQ test.

While we can probably all attest to a friend who is “smart but lazy,” or smart but interested in a field that doesn’t pay very well, like art or parenting, the correlation between IQ and life outcomes (eg, money) are amazingly solid:

Thanks to

Thanks to Pumpkin Person

Thanks to
And if this makes us feel mercenary, well, other traits also correlate:
Shamelessly stolen from Jayman's post.
Shamelessly stolen from Jayman.

The correlation even holds internationally:

Source Wikipedia
Map of IQ by country. Source: Wikipedia.

I do wonder why he made the graph so much bigger than the relevant part
Lifted gratefully from La Griffe Du Lion’s Smart Fraction II article

There’s a simple reason why this correlation holds despite lazy and non-money-oriented smart people: there are also lazy and non-money-oriented dumb people, and lazy smart people tend to make more money and make better long-term financial decisions than lazy dumb people.

Note that none of these graphs are the result of a single test. A single test would, indeed, be useless.

To be continued…

10 thoughts on “Comments on Chauncey Tinker’s Intelligence, Concentration, and IQ Tests

  1. >Folks who study IQ for a living, like the famous Flynn, believe that environmental effects like the elimination of leaded gasoline and general improvements in nutrition have raised average IQ scores over the past century or two. (Which I agree seems pretty likely.)

    To me this seems unlikely because while IQ has gone up, other things that correlate strongly with g have not. There’s no Flynn effect in reaction times or pitch discrimination. This points to the Flynn effect being mostly a matter of improved test-taking ability rather than an increase in g.

    Liked by 1 person

  2. Not a big fan of Flynn.
    I’ve been following some U.K. I.Q. bloggers, which got me to Woodley’s research.
    They think I.Q. in the U.K., and presumably in the West more generally, has been slowly dropping since the 1800s, which makes sense to me. The revolutionary movements led to the modern state, and a dysgenic environment.
    Flynn is measuring noise. Or perhaps the fact that people learn, over time, how to take I.Q. tests.

    Liked by 1 person

  3. Thanks, this is just the sort of feedback I was hoping for, we seem to be pretty much in agreement on this. This post was really just to make it clear how I regard IQ tests before I wrote the posts on dysgenics. I don’t really have time to get into the subject in great detail because I’m more focused on current affairs issues.

    The map seems particularly damning – many people thought that Lynn was racially motivated when he produced those stats. Attempts to blame environmental factors such as colonial interference in those cultures fall flat when you look at the fact that other former colonies such as Singapore have thrived and have high IQ stats. However I strongly suspect there is also a sort of compounding negative effect in undeveloped and strife-ridden areas on IQ due to the constant presence of danger and lack of education. What might be revealing here is to study migrants – try to get an IQ test before and after they migrate, and then more tests later once they are established in a safer and more prosperous country. My own suspicion is that the differences that the map seems to show in “g” are very real between the areas, but that probably they are somewhat exaggerated by the local problems in those areas.

    When I mentioned learning I was thinking a bit beyond just education. I heard there have been attempts to make IQ tests less dependent on such factors, for example if a test requires some mental arithmetic then (I think) obviously someone who does a lot with numbers is going to score better. Surely we can develop abilities such as this through practice, so can particular abilities really be completely removed from IQ tests? Is it possible that someone who works a lot with shapes can develop faster abilities in that area through practice? Obviously someone who is completely illiterate is not going to be able to do an IQ test at all, unless it can be done entirely with pictures. (All the IQ tests I’ve ever done had some words). Then there’s a grey area where someone is semi-literate, but has to stop and think a bit about each word to remember what it means. That’s going to mean they have less time to actually solve each test. Where you say “this effect fades with age” when we are talking about populations that are still largely illiterate, this literacy effect is not going to fade however if they are never educated.


    • You’re welcome. I’m glad it was useful.
      My impression is that the IQ test makers have worked hard to remove any effects of reading ability, eg, by having tests that are orally administered and involve rotating shapes. (I hear they really thought they had a good, un-gameable test there until Tetris came along and Tetris players started doing really well on mental shape rotation.) Ultimately, I don’t think it’s possible to make a test that isn’t gameable (or influenced by prior practice/experience)–the theory that the “Flynn effect” is at least partially due to people becoming more familiar with IQ tests, for example, seems likely. People who’ve never seen an IQ test before, in cultures where paper and literacy don’t exist, probably feel a fair amount of confusion about why this crazy stranger is trying to make them rotate shapes, decide the whole thing is kind of stupid, and quit early to go hunt down some food, because hunting food makes sense.

      But that’s just some bathwater that comes with the baby. I’m willing to say that IQ is imperfect, but it’s a pretty good measure of what we want to measure, which in my case is economic development. Clearly whatever skills are measured on an IQ test (potentially even “ability to do an IQ test”) are strongly correlated with “building a nice society with lots of food and running water.” And illiterate people tend not to build very complex societies, even if they could have had they been literate.

      Africa is an interesting case. (“Colonialism” is a stupid excuse. Ethiopia was never colonized and it’s one of the world’s shittiest places.) I would not be surprised to see a big jump in IQ (ie, 5 – 10 pts) in some African countries over the next 50-100 years. New technology (which Africa has been given in spades) + better health + no welfare state = a lot of opportunities for smart people to get ahead.

      Of course, if the Middle Eastern countries could just ban cousin marriage, the next generation would see an immediate increase in average IQ.

      Liked by 1 person

      • Right, that all makes sense to me. I am pretty sure from all that I have seen that “g” is actually significantly lower on average in these places currently despite my reservations about exactly how well IQ measures “g”. I think simply the fact that these countries have remained underdeveloped for so long despite the available technology tends to confirm that. Another factor is the fact that the West has long acted as a brain drain on these places as well.

        Our “leaders” seem to be entirely clueless about the likely effects of allowing in millions of people who will probably be fairly unemployable on the whole in our high tech societies. They may even bring down the welfare state and well, you never know that at least might not be a bad thing in the long run, although chaos could be a short term consequence. The sooner we face these realities honestly the better:


        “Although the companies surveyed employ four million workers, FAZ reported that between them, they had only hired 54 migrants.”

        “said his research showed at least two thirds of migrants can’t read or write.”


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s