Americans' Average IQs Up 18 Points in 50 Years

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New Zealand political scientist James Flynn talks about the IQ trends he discovered over at Cato Unbound. To wit:

Americans made massive IQ gains on the WISC [Wechsler Intelligence Scale for Children] between 1947 and 2002 amounting to almost 18 points of Full Scale IQ. These gains ranged from only 2 points on the WISC subtest called Information to 24 points on the subtest called Similarites (what do dogs and rabbits have in common?), despite the fact that both have the cognitive complexity that makes them good measures of g.

Obviously such a rapid increase in average IQs can't be attributed to genetic factors. Flynn's essay makes some smart observations about how the interaction of genetic and environmental factors influence an individual's level of general intelligence.  

Whole Flynn essay here.  

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  1. Sorry folks, I must have skewered the numbers…

  2. Average IQ may be up (if the study is accurate), but so are occurrences of people doing stupid shit!

  3. Sorry folks, I must have skewered the numbers

    Good thing there is nothing on the IQ test about skewered vs. skewed.

  4. Shouldn’t all those dirty hispanics be bringing it down? /snark

  5. That real purty nooz.
    IQ’s got all biggend!!!111
    duh duh duhh duhduudh brbrbbbbb

  6. Just a quick note to remind everyone that genes are still as important as they always were.

    Yes, these results indicate that the claim that each of us has a fixed IQ that we’re born with and that is independent of any environmental factors, is ridiculous. Obviously genes don’t generally mutate fast enough to explain an (across the board!) massive IQ increase within two generations. Nevertheless, the more intellectually able are STILL – after all of the increase-dust has settled – smarter than those born with lesser cerebral gifts.

    Innate talent and intelligence – and the fact that there are differences between us – are still real. And THIS FACT STILL needs to be taken into account when it comes to public policy.

    Are you a free-marketer who worships at the twin alters of Efficiency and Ability? Then you’d better make sure no one thinks that all people are the same and thus that your average pygmy-baby and Chinese-baby are born with the same abilities and thus ought to have the same amount of community money expended on them.

    But if you’re NOT a Nazi then you might want to stop holding blinders to your face in believing that financially unsuccessful people are in that position owing either to their own moral failings or owing to RacismSexismEtcism and you might care to create a more equitable financial system so that being born slightly less smart isn’t (in 90% of the cases) a sentence of stress and suffering for the extent of one’s entire natural life.

    Honestly, you lucky-born smart ones would LOVE to believe in the Tabula Rasa. It’s so self-complimentary (“I made it because I worked hard!”) and so comfortable a dogma when considering the suffering (“They made their OWN bed that they sleep in! Why didn’t they go to Law School like I did!) – but, by God, it’s pure bullshit.

    mnuez
    http://www.mnuez.blogspot.com

  7. It’s the robots.

  8. I sort of figured it was nutrition. Maybe he says that, but I didn’t RTFA.

  9. As I always thought: People in 1947 were dumber than cow plop.

  10. Imagine what these comment boards would have looked like before we were as smart as we are now.

  11. Hmm, I should take this IQ test. Maybe I’ll finally squeak into “average”.

  12. Its the Gilmore Factor

  13. Its the Gilmore Factor

    Talking super fast about random pop culture flotsam while female friendly neo-singer-songwriter fluff plays in the background and pervaded with a general sense of whimsy?

  14. Has this test been “recentered” a dozen times, like the SATs? is there a curve here?

  15. mnuez,

    Your point?

    What policy changes or current policies do you feel this data supports?

    Environmental factors are larger than innate factors. Therefore policies that are based on improving the environment are, overall, going to have the best results.

  16. Are you a free-marketer who worships at the twin alters of Efficiency and Ability? Then you’d better make sure no one thinks that all people are the same and thus that your average pygmy-baby and Chinese-baby …

    Funny, I’m a free marketer, and if you were to inform me that the average pygmy IQ is ten points higher than the average Chinese IQ (or whatever), I would regard it as a trivial factoid that wouldn’t help me in dealing with the pygmy or Chinese individuals with whom I happen to be dealing.

  17. de stijl,
    “I like you. You make me laugh.”

    But by god that show sucked.

  18. NM,

    Socialistic policies that don’t let a hundred million Americans live with toothaches for years because they can’t afford to go to a dentist.

    Mike,

    You’re obviously not too bright, but I did enjoy your attempt with the pygmy/chinese switcharoo. So tell me Miko, is Ignorance really Strength?

    Anyhow, I know that you likely wouldn’t treat them any differently but your policies have the net effect of bringing a life of suffering to one and a life of pleasure to the other – all owing to some dumb luck as to what sort of biological tissue is encased in their skulls. And for that reason, nice as you likely are in personal life, I believe that you cause lots of pain and are worthy of scorn.

    So even though in your personal life you probably don’t live in accordance with the Free Market dogma that you preach, that says nothing about the consequences of the dogma that you vote for and advocate. What it does say is something about you: You aren’t intelligent enough to understand what your dogma actually means, resulting in the strange hypocrisy between how you live and the consequences of how you vote.

    mnuez
    http://www.mnuez.blogspot.com

  19. “what do dogs and rabbits have in common?”

    Both taste like chicken?

  20. @ groucho | November 5, 2007, 4:01pm | #

    Has this test been “recentered” a dozen times, like the SATs? is there a curve here?

    IQ tests track assimilation more than brains. How can you really measure an abstract concept like someone’s potential, anyway?

  21. Environmental factors are larger than innate factors. Therefore policies that are based on improving the environment are, overall, going to have the best results

    Definitely. Intelligence is very dynamic and habits (challenging oneself, etc.) are very important.

  22. ” – but, by God, it’s pure bullshit.”

    A summary, no doubt, of your entire post.

  23. You all realize that this blows “Drop the” Chalupa’s yesterday argument out of the water, right?

    Graucho – yes the SAT has been recentered so every kid that takes it can be in the 85% and thereby, “special”.

  24. “but your policies have the net effect of bringing a life of suffering to one and a life of pleasure to the other”

    Only a top-shelf moron thinks there’s just the one pie.

  25. Was that higher average IQ measured during the week that DONDEROOOOOOOOOOOOOOOOOOOOOOOOOOOO was in Mexico?

    I wonder how many IQ points we dropped upon his return.

  26. mnuez,

    Ignoring your childish insults about dogma, blinders, worship, blahblahblah, your rather strange “pygmy-baby”/”Chinese-baby” analogy suggests that you still don’t understand that differences in innate intelligence among different individuals are not the same as differences in innate intelligence among races. The former are very well established; the latter are not. Which is not to say there aren’t social policies that can or should be instituted to help those in difficult environmental circumstances; but ideally it could be discussed without the race-baiting.

  27. If you measured kid’s heights you’d probably also find a rising trend between 1947 and today.

    Like IQ, height is mostly genetic, but is influenced by other environmental factors (nutrition, childhood disease, etc…), along with some element of randomness.

    Any opinions on what percentage of adult IQ determination is:

    1) Genetic
    2) Environmental
    3) Random

  28. You’re right, mnuez! I understand now that the free market dogma I advocate hurts people, not like socialism! Thank you for showing me the light!

    Of course, none would be more surprised than ,mnuez if someone did convert. After all, he’s not here to change minds-that requires engagement and argumentation, not insults and the braying one’s own dogma-he’s here to be noticed, and to feel important.

    So, consider yourself noticed, mnuez.

  29. Has this test been “recentered” a dozen times, like the SATs? is there a curve here?

    There have been four editions of the WISC, renormalized in part to compensate for the phenomena of rising IQ scores described by Professor Flynn.

  30. What makes anyone think that “g” exists, or that they know how to appropriately measure it?

  31. Mr 99th

    I would say it is unknown at the moment.

    A nice couple of discussions of the topic.

    http://bactra.org/weblog/520.html
    http://bactra.org/weblog/523.html

  32. For adults, I’d say 80% genetic, 10% environment, 10% random.

    However, for kids I’d go with 65% genetic, 25% environment, 10% random.

    I figure, for kids of any given age, differences in parenting and schooling offering better (or worse) learning opportunities would accelerate (or delay) cognitive development, leading to higher (or lower) test scores.

    But by adulthood, everyone’s development would have had time to catch up, and environment would become less of a determining factor.


  33. Are you a free-marketer who worships at the twin alters of Efficiency and Ability?

    i know this wasn’t on purpose, because you’re not that creative, but this was an excellent typo and i enjoyed it thoroughly.

    A++, would snark again.

  34. Alkali,

    That link in my last post numbered 523 gives a great run down on how “g” came about and what it does or doesn’t mean.

  35. I suck at algebra. How the fuck am I supposed to solve for g? I don’t even know what the fuck that means!

  36. This is just confirmation that the genetic component of “intelligence” isn’t all it’s cracked up to be. IQ tests measure your ability to take tests. I’m good at that, hence, high IQ score. It doesn’t mean diddly.

    Certainly some people are born smarter than others. Equally certain is that environment has a huge impact on peoples “intelligence”. Factor in that IQ tests do NOT measure “intelligence” and all of a sudden, Grand Chalupa looks like an ill informrd bigot. Wait, he’s always looked like that.

  37. You all realize that this blows “Drop the” Chalupa’s yesterday argument out of the water, right?

    I think what you’re trying to say is that the LeftieLibertarians are refusing to acknowledge the PlainTruth that GeniusMexicans with their EvilSmarts are taking over OurCountry.

  38. This took place during a period when the % of the American population that is characterized as “non-Hispanic white” has been steady decline.

    Which proves absolutely nothing…although it does put a rather large hole in certain people’s theories.

  39. de stijl | November 5, 2007, 3:57pm | #

    GILMORE SAYS =
    Its the Gilmore Factor

    Talking super fast about random pop culture flotsam while female friendly neo-singer-songwriter fluff plays in the background and pervaded with a general sense of whimsy?

    Eh?

    Dude, you know nothing of my work.

    It’s talking super fast about Cippola’s theory of the nature of human stupidity, the better parts of William S Burroughs, why Montaigne and Eric Hoffer should be required reading in High School, backed by a mix of new orleans parade music, The Stooges, and 80s Atlanta Booty

    I could care less about pop culture

    Except maybe for the influence of 2Live Crew on contemporary culture

  40. This took place during a period when the % of the American population that is characterized as “non-Hispanic white” has been steady decline.

    Which proves absolutely nothing…although it does put a rather large hole in certain people’s theories.

    It does, doesn’t it? 😉
    Not any of mine, though. Hence the smiley face.

  41. de stijl | November 5, 2007, 5:00pm | #
    I suck at algebra. How the fuck am I supposed to solve for g?

    All your answers are found in the first NWA album. You start with the first axiom = whatup g?

  42. It sure does.

    🙂

  43. You’re obviously not too bright, but I did enjoy your attempt with the pygmy/chinese switcharoo.

    Thank you. But are you saying that you actually have data comparing the IQs of pygmies and Chinese people? If not, why do you assume there was a switcheroo? From a few weeks of studying their culture in my college Anthropology class, I know that pygmies are pretty darned intelligent about surviving in the jungle. Have you ever done any jungle survival time?

    Anyhow, I know that you likely wouldn’t treat them any differently but your policies…

    I have policies?

  44. joe, We’re supposed to argue and snipe after each other. Tomorrow OK with you?

  45. The only thing IQ tests measure is how well one does on IQ tests. Similar comments can be said about the SAT, GREs and LSATs. Such tests judge only how well the testee maps on to the mental thought processes of the person who constructed the question.

    One reason why I now suck at all the above. I’ve lived in too many countries, know too many languages, and have had too much material poured into my brain to take *any* of the “totally obvious” assumptions inherent in such test questions for granted. I often can come up with a totally logical and consistent set of reasons for one of the “erroneous” answers.

  46. I know that pygmies are pretty darned intelligent about surviving in the jungle. Have you ever done any jungle survival time?

    Old Lame Joke Warning!

    Q. Do you speak polish?

    A. No I don’t.

    Q. How does it feel being dumber than a polack?

  47. Obviously such a rapid increase in average IQs can’t be attributed to genetic factors.

    Asians in the gene pool.
    Asian immigration was severely restriected before
    the War.

  48. Scores go up because they keep dumbing down the test, just like we do with the SAT. “Bright normal” is the new moron.

  49. Scores go up because they keep dumbing down the test, just like we do with the SAT. “Bright normal” is the new moron.

    In reality, they’ve had to re-norm the IQ test because people do so well on it, not because they do badly. Do a little research before calling people morons.

  50. In reality, they’ve had to re-norm the IQ test because people do so well on it, not because they do badly.

    Or so they would have the formerly scaled moron “bright normals” believe!

  51. It is among the glories of mathematics that no matter how many IQ points Americans gain, half always seem to be left wondering how they can be of less than average intelligence?

  52. The fact that average IQ scores are on the rise is less revealing than that an individual can raise his/her score by study and/or practice.

    Perhaps more significant is that so few tasks in everyday life require the application of great intelligence. While entirely annecdotal, my own observations have demonstrated that people of average or lower IQ scores can make great contributions to society and lead happy, productive lives, while many of their higher scoring peers have contributed very little. Even worse, some use their supposedly greater intelligence to inflict pain and suffering on those they deem less important.

    IQ scores are a poor measure of one’s value to society and humanity.

  53. Any opinions on what percentage of adult IQ determination is:

    1) Genetic
    2) Environmental
    3) Random

    1) 80%
    2) 19.99%
    3) .001%

  54. Are you a free-marketer who worships at the twin alters of Efficiency and Ability?

    i know this wasn’t on purpose, because you’re not that creative, but this was an excellent typo and i enjoyed it thoroughly.

    A++, would snark again.

    Dhex, the only typo I see is “marketer” should be “marketeer”. That does not strike me as remarkably funny. Since I like to laugh, I must be missing something. Would you please explain?

  55. wayne,

    altar vs. alter

  56. I’ve noticed that by far the greatest and the most arrogant lies are introduced as self-evident and non-controversially styled in a “of-course-this-is-so” fashion. This article is no exception, by far the most controversial and debatable point is taken care with the phrase “obviously”.

    “Obviously such a rapid increase in average IQs can’t be attributed to genetic factors”. Uh-huh. That’s three generations. Why not? If the author has any sort of factual proof behind this statement, why doesn’t he lay it down for all of us to see?

    The lack of “self-evident” ideological prejudices written as Truth compared to mainstream media is the reason I started reading Reason online in the first place.

  57. reader,

    Such a dramatic change can’t be attributed to genetic causes because some basic population genetic theory makes it crystal clear that genetic factors underlying IQ wouldn’t change in frequency anywhere near that much in only three generations in a population as large as the US unless selective pressures were absolutely huge – as in people with lower IQs dying in droves before they had a chance to reproduce. Since that’s obviously not happening (in fact, I’m not aware of any evidence that lower IQ is associated with lower fitness at all, although it may be out there), something else beyond genetics is going on. It may not be self-evident to people not familiar with the math underlying it, but it’s certainly not a lie, arrogant or otherwise.

  58. While entirely annecdotal, my own observations have demonstrated that people of average or lower IQ scores can make great contributions to society and lead happy, productive lives, while many of their higher scoring peers have contributed very little.

    Amen.

    There is a genetic component. You can’t be a rocket scientist if your intellectual capacity is two steps above that of a small, hand held lizard (you might call such a person “a lizard head”).

    But barring the extremes of the distribution curve, individual will is (my opinion) the dominant factor in the long run.

    Raw intelligence, by itself, is utterly useless. I had many class mates in grad school who were as lazy as they were brilliant. Their careers since have been mediocre, as you might expect.

    I’ve come to take people who score extremely high on GREs, IQ tests, etc, as inherently suspect. More often than not I have found that these people have a particular skill — figuring out what their “uppers” and “superiors” are going to ask of them next — and yet they are utterly lacking in the capacity to do innovative or original thinking.

    Many, many of the ground breaking, path blazing R&D people I know in math and science, were not in the tops of their classes, did not max out the standardized exams, and did not get the big name scholarships.

    Einstein nearly flunked math at one point, and he was never particularly good at it, at any point in his life.

    Just because Einstein was a great physicist does not mean he would ever have been more than a mediocre pianist.

    When aptitude and will coincide, that’s where the proverbial “movers and shakers” come from.

  59. Welcome to America, where all the women are strong, all the men are good-looking, and all the children are above average.

  60. Ebeneezer,

    I agree with nearly all of your points. Intelligence is one critical component in creativity, but as you point out, there are others as well.

    I would be astonished if Albert Einstein scored poorly on an IQ test, though. I once read an article in a magazine that estimated the IQs of some of the world’s great thinkers and artists. I think Albert’s IQ was estimated to be about 160. Leonardo DiVinci’s IQ was estimated to be 200 if my memory serves correctly.

  61. I would be astonished if Albert Einstein scored poorly on an IQ test, though.

    I’d agree with that. But, how many different fields of endeavor could he have chosen, and still made a real impact on the world?

    Di Vinci was an outlier, one of the true aberrations. Maybe Aristotle too, and a few others.

    I don’t deny that the outliers exist. There have been intellectual giants. A very few of them have actually been multi-talented, but that’s exceedingly rare.

    Anyway, good thread.

  62. J sub D,

    joe, We’re supposed to argue and snipe after each other. Tomorrow OK with you?

    OK. Ahem.

    All indications suggest that your mother is not wholly unacquainted with the physical act of love.

    Boo-yah!

  63. You all realize that this blows “Drop the” Chalupa’s yesterday argument out of the water, right?

    Nope, the difference between the races still exist. The gap between whites and blacks has narrowed but stabilized years ago.

    Sorry.

  64. Taktix, I think GC is singlehandedly offesetting any bump you may be giving to the stats.

  65. [i]Such a dramatic change can’t be attributed to genetic causes because some basic population genetic theory makes it crystal clear that genetic factors underlying IQ wouldn’t change in frequency anywhere near that much in only three generations in a population as large as the US unless selective pressures were absolutely huge [/i]

    …. like 30 million abortions? Maybe the feti were on the dim side?

  66. Grande Chalupa (our shallow boat),

    Care to address any of the substantive points in Flynn’s essay?

    To whit: can you explain how the difference you cite would be a justification for reducing environmental interventions for those at the bottom of the “g” curve, when Flynn’s data would support increased intervention?

  67. Actually, a large and significant increase in median IQ during a period when non-white people have grown considerably as a % of the population is a pretty good refutation of the theory that white people have higher median intelligence.

  68. The myth that ‘Einstein was bad at math’ is something that some people find comfort in, I guess. Despite numerous books and documentaries that have busted this myth, it persists. It’s true that he was unfamiliar with certain branches of high-level mathematics, and occassionally asked his colleagues for help, but he cetainly had a gift for Math as well as for Physics.

    I blame the rise in IQ scores on Global Warming and Flintstone vitamins.

  69. Maybe the “large and significant increase in median IQ” of a population simply means that standard IQ tests have a shelf-life.

    It seems reasonable to me that teachers and educational bureaucrats would specifically teach the subjects that are tested for in IQ tests. If that is the case, then one would expect to see a “large and significant increase in median IQ” over a generation or two.

    It seems to me the challenge facing IQ testers is to continually develop new tests that defeat the teacher’s attempts to ‘beat the system’.

    Bottom line, in my opinion this upward drift in IQ scores represents nothing damaging to the notion of “g”, and certainly does not signal that society is getting “more intelligent”.

  70. Wayne,

    It would require that you don’t understand the logical foundations underlying the notion of “g” to put all those conjectures into one post.

    http://bactra.org/weblog/523.html

    Building factors from correlations is fine as data reduction, but deeply unsuited to finding causal structures. The mythical aspect of g isn’t that it can be defined, or, having been defined, that it describes a lot of the correlations on intelligence tests; the myth is that this tells us anything more than that those tests are positively correlated. It has been known for almost as long as factor analysis has been around that positive correlations can arise in many ways which involve nothing remotely like a general factor of intelligence. Thomson’s ability-sampling model, with its myriad independent causes rather than a single general cause, is the oldest and most extreme counter-example, but it is far from the only one. It is still conceivable that those positive correlations are all caused by a general factor of intelligence, but we ought to be long since past the point where supporters of that view were advancing arguments on the basis of evidence other than those correlations. So far as I can tell, however, nobody has presented a case for g apart from thoroughly invalid arguments from factor analysis; that is, the myth.

  71. NM,

    So, is your point that there is no such thing as “g”? Is “g” not heritable?

    Instead of telling me what I DON’t think, tell me what you DO think.

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