Tuesday 3 November 2015

Deutschland über alles, dann unter allen?


The Flynn Effect is a funny mixture: part IQ inflation, part civilizational advantage. It seems that ever since intelligence testing began, people have been getting smarter. That is not too surprising. The first world war partly destroyed Europe, but the slaughter caused by the Gatling gun was matched by the ability to bring food across the world, preserved in tin cans and refrigerated ships. Nutrition improved. The second world war brought destruction world wide, but also spurred innovation. Since 1945 the world has got richer. More of the world was exposed to better nutrition, health and education. Since the 1990s the world has got healthier and better educated and even richer. Complain as we might, most people on the planet are living better lives than ever before. All this should boost the human condition, and as we become more civilised, both mind and body improve. Test scores record this improvement. This is the rosy view of rising intelligence.

The cautious view is that modern life sets us more IQ type questions, and problems which seemed out of the ordinary in the early part of the 20th Century soon became commonplace, because of better and more widespread education. IQ tests have become less puzzling, less of a test, because they look like familiar items in regular school tests. Therefore, the apparent gains are hollow, and there is no real life proof that we are getting as much brighter as the tests suggest. We are suffering IQ inflation, not a real increase in intellectual wealth.

The contrary view is that if you use proper tests: reaction times, digit span, colour perception, then there is slight but unmistakeable evidence of mental decay, and falling real intelligence.

And now to Germany.

A reversal of the Flynn effect for spatial perception in German-speaking countries: Evidence from a cross-temporal IRT-based meta-analysis (1977–2014) Jakob Pietschnig and Georg Gittler. Intelligence 53 (2015) 145–153.


In their abstract Pietschnig and Gittler say: Generational IQ changes (the Flynn effect) have been shown to be predominantly positive but differentiated according to IQ domains and countries. However, evidence from recent studies points towards a decrease of the Flynn effect globally or even a reversal in some countries. In the present meta-analysis, we show an inverse u-shaped trajectory of IQ test performance changes in a large number of samples (k = 96; N = 13,172) on a well known test for spatial perception (the three-dimensional cubes test, 3DC) in German-speaking countries over 38 years (1977–2014). Assessment of both item response theory-based measures as well as more standard measures of classical test theory showed initial increases and a subsequent decrease of performance when controlling for age, sample type (general population vs. mixed samples vs. university students) and sex. Our results suggest saturation and diminishing returns of IQ increasing factors (e.g., life history speed) whilst negative associations of IQ changes with psychometric g may have led to the observed IQ score decrease in more recent years.

Here are the u-shaped historical trends, shown either as ability parameters or percentage of solved items, both giving the same overall picture.

German nv IQ

So, has Germany abolished itself?

The authors give some background: Worldwide IQ gains have been shown to have started to slow down in the past decades across all domains. This has been interpreted as a potential predecessor for a stagnation or even reversal of gains in the future (Pietschnig & Voracek, 2015). In fact, stagnation of gains has been reported in data from Norway and Sweden (Emanuelsson, Reuterberg, & Svensson, 1993; Sundet, Barlaug, & Torjussen, 2004). More recent findings even indicate a reversal of IQ gains in Denmark, Finland, and France in past decades (Dutton & Lynn, 2013, 2015; Teasdale & Owen, 2005). Interestingly, declines in reaction times over more than one century indicate that contrary to the frequently observed IQ gains, generational changes in psychometric g may have been in fact negative in Western countries (Woodley, te Nijenhuis, & Murphy, 2013, 2014; Woodley of Menie, te Nijenhuis, & Murphy, 2015). Therefore, it seems likely that IQ changes in further countries may eventually show a similar trajectory of an initial stagnation and subsequent decrease of IQ test performance

They go on to make a crucial point: IRT-based estimates [are] more accurate than conventional raw scores within the framework of classical test theory, where each correct item solution is equivalent to one raw score point, regardless of the item's difficulty.

We investigate changes in spatial IQ performance of the general population on the three-dimensional cubes test (3DC) over a time-span of 38 years in German speaking countries. In our main analysis, we focus on changes of IRT based mean person parameters of samples and support our findings by supplementary analyses of estimates derived from classical test theory. Moreover, we investigate influences of sample age, sample type (general population vs. mixed samples vs. university students), and sex on spatial task performance.

In contrast to many cognitive ability measures, item difficulty of the 3DC is not progressively increasing throughout the test, but rather easier and more difficult items alternate

In all, 96 independent samples (N = 13,172) from 76 published and unpublished studies were included in the present meta-analysis. Participants in primary studies were predominantly from healthy convenience samples in schools, Universities, and from the general population.

Here is the key result: Results from our linear regression analyses suggest decreases of about 4.8 IQ points per decade when controlling for age, sample type, and sex, thus indicating a substantial negative Flynn effect that is even stronger compared to previously observed positive trends (e.g., Flynn, 1984, 1987; Pietschnig & Voracek, 2015). This trend was observed in linear regression analyses, but our results showed that the present changes over time may be even better described as a curvilinear function, thus indicating initial increases, followed by stagnation (with performance peaking around the mid-1990s), and subsequent decreases of task performance. This curvilinear relationship emerged for both IRT- as well as non-IRT-based measures and remained robust when controlling for age, sample type, and sex, thus corroborating stability of our results and further corroborating validity of the Rasch model in our samples.

The fall in intelligence is quite severe. The authors soberly go through a list of possible explanations for IQ having been boosted by cultural changes but then subject to diminishing returns, finally tentatively landing on: One possible reason may be that the above discussed IQ-boosting factors have masked the g-based ability decrease until a point of saturation was reached. If this is so, the zenith of our curvilinear regression would approximately give the point where beneficial factors were eventually outperformed by the negative trend in g.

If life is dandy, particularly in wealthy Germany, workshop of the world, what could be causing a drop in intelligence?  The authors comment: Other potential reasons that have been cited for decreasing IQ test scores such as changing population ability levels due to non-Western immigration (e.g., Rindermann & Thompson, 2014) or dysgenic fertility patterns (e.g., Lynn, 2011) do not seem suitable to contribute substantially to our present findings. On the one hand, effects of immigration on national IQ levels were observed not to be long-lasting with performance gaps diminishing over time (te Nijenhuis, de Jong, Evers, & van der Flier, 2004). On the other hand, both immigration and dysgenic fertility effects have been shown to be too small to provide substantial contributions for our present findings (Meisenberg & Kaul, 2010; Rindermann & Thompson, 2014).

Comment: Rindermann & Thompson (2014) calculate that, on average, the mean natives' and immigrants' competence gap is equivalent to 4.71 IQ points, which by coincidence is precisely the drop experienced in Germany. How much of an effect do immigrants contribute?

(By way of a brief aside, as of 2012 Germany was 80% German. Another 3.9% are European, but that includes a substantial 1.9% Polish (IQ92) 1% Italian (IQ97) 0.5% Romanian (IQ91), 0.5% Greek (IQ92) and 2.9% others Spanish(97), Croatian (99), Dutch, Portuguese and Austrians. Many but not all are significantly below the German mean of IQ99.   3.7% of the population are Turkish (IQ88) and this should have a bigger effect.

Here is the entry for Germany in our 2014 paper:

Natives constitute 81% of the population, their competence is (IQ) 100.99

Migrants constitute 19% of the population, their competence is (IQ) 92.75

Competence difference –8.26 IQ points

This certainly looks like it should push Germany back a bit, but at only one fifth of the population the migrant effect is still relatively slight and takes the national mean down only to 99.4. However, if we plot migration numbers by year it might match some of the effect, so it could be a partial contributor, though far from the whole story. Dysgenic trends might be a further contributor, so we can follow that argument by seeing what Woodley makes of a similar drop in ability in France, which I hope to post about shortly.

The authors’ final words are: This may most likely be due to saturation and diminishing returns of IQ boosting factors (e.g., life history speed) and a manifestation of declining psychometric g.

Comment: Saturation and diminishing returns, as the authors make clear, would result in improvement being sustained at a plateau. In fact, in these results abilities have fallen as fast and as far as they had previously risen, which is an alarming finding. All that could explain that (if immigration is taken out of the picture) is declining psychometric g, which presents Germany with a substantial German problem. This is particularly sobering because the sample is younger than the general population (84% are below 30 years of age) so the young generation is duller than the older, not the usual pattern. (Incidentally, it makes me wonder whether immigrants, with greater family size are contributing more to this younger population).

Here is a testable prediction: if Germany takes in the projected numbers of Middle East immigrants, then that will boost the immigrant origins population by at least 1 million. Once their families join them the number could be 3 or 4 million. In all probability this will have a negative effect on German national intelligence levels. (It makes no difference whether they are from Syria or Pakistan, since roughly IQ 83 is expected from either). However, we do not need to wait very long to test all this. If a German researcher is quick about it, they could pop round the reception centres and give the three dimensional cube test to as many new immigrants as possible, and we could have the answer in a few months. Indeed, giving a few more intelligence tests would be predictive for training and occupational placement purposes. A thesis in it for someone?


  1. Boche biffed by beaucoup bozos.

    1. Worthy of Bild. Authors tell me most subjects were German speaking Austrians, but same general arguments hold.

    2. They're all Boche.

  2. Gatling is not a synonym for machine gun. The Gatling was a very specific firearm that had long since been rendered obsolete before the war in question. The last time it saw any use that I'm aware of is around the time Teddy Roosevelt was hiking up San Juan Hill.

    Your use of the term there is a bit like stating that the Kaiser used Zeppelins during the London Blitz in WWII.

    The most iconic weapon of WWI would likely be the Maxim and its derivatives, like the early Vickers and the MG 08.

  3. Maxim! My mistake. Take your other points.

  4. There are differences between ''study to play violin or other musical instrument'' during childhood than adult life??? Children learn faster than adult, is not??

    Musical prodigious tend to start to play musical instrument in the early life. But if they or at least a one them was placed as a child in a deprived environment, without the availability of musical instruments.

    And he was exposed to musical instrument only when he became adult. Would he be able to learn the same way, at the same level, as a child, or learning will be more difficult and would be likely that he not become a prodigious virtuoso ???

  5. I don’t think your Polish IQ figure of 92 is correct. I’ve read it’s 99 - only slightly lower than Germany’s. Poland currently does better than Germany on PISA scores in all categories - it’s Europe’s educational rising star.

    Over the centuries there’s been a fair amount of German-Polish mixing, especially in border regions. In the 19th century Poles living in Prussian-German Silesia were under pressure to Germanise if they wanted to get ahead; the surprisingly large number of “native” Germans whose surname ends in “-ski” almost certainly have part Polish ancestry. (On the other hand, Nietzsche’s claim his family was really Polish is almost certainly false; he was just being facetiously anti-German.)

    1. Buj, 1981
      Jaworowska & Szustrowa, 1991
      Raven et al., 2000
      Raven, 2008
      Dobrean et al., 2008

      I based it on the above papers, but very happy to update, since it seemed too low.

  6. Do you accept comments from Wordpress accounts? Because I tried submitting a comment above but I don't see it...

    Anyhow, this is off topic: I've run into a problem, which may sound stupid or silly or unlikely. I don't have many smart people to interact with on a daily basis, or at least no one around me seems smart. They all seem really frickin' stupid. I spend all my time on the Internet because there's so many idiots around me everywhere.

    So let's assume I'm looking to find people with IQs over 115-120 or so to communicate with. Not that I'm a genius myself, as my WAIS-IV IQ is only 120, but my general knowledge and interests are far deeper than most people with my IQ. I choose the threshold of 115-120 because these are the people smart enough to hold intelligent conversations and form their own opinions (not regurgitate crap they hear on TV). I wanna be able to do the following with random people I meet:

    1) Hold a conversation for less than 5 minutes
    2) Ask a question about their lifestyle/interests that will immediately give me an accurate estimate of whether their IQ is above the threshold mentioned above.

    That's it. I'm a college graduate from a decent university, so I could swing by the Alumni Building sometime to hold deep conversations with them but I'm too busy at work.

    I don't want to ask people for their IQ/SAT scores, or for those of their family members. I could ask them what university they graduated from or whether or not they majored in STEM, or if they're an engineer/doctor, but that's too easy :D (and that will risk too many false negatives, maybe a few false positives too)

    I've had some of the following ideas:
    1) Ask them if they like classical music. Linda Gottfredson claims that a preference for classical music is a strong predictor of triple digit IQ. This statement actually inspired me to try this exercise in the first place. This question doesn't seem like it would indicate too many false positives, but I think there would be a lot of false negatives. Plus, I wanna meet a higher threshold than that.
    2) Ask them if they've had children out wedlock. If they're a "baby's mama" or if they have one, that's pretty solid indicator in the opposite direction (IQ lower than 115). But going by that may lead to too many false positives for IQ above 115.
    3) Ask them if they've ever been incarcerated. Pretty much the same thing as above, although moreso as far as false positives, because of fewer people being incarcerated, even those below 115.
    4) Ask them, "Have you read more than ____ (some #) of books for personal pleasure in the past year?" I'm guessing people above 115 would've read at least a half dozen books for personal pleasure during the year.
    5) Ask them, "Do you read IQ blogs?" Will weed out a lot people who may be smart enough, though.
    6) Ask them, "Do you have any African ancestry in the last few generations?" wouldn't give too many false negatives, but of course would give a whole lot of false positives too.
    7) Ask them some series of vocabulary words (or maybe a short digit span test)? That's too easy, though, more looking for lifestyle type questions that could come up in the course of conversation.
    8) Ask them, "do you like math?" If they say no, most surely IQ < 115.
    9) Ask them their net wealth. Inappropriate.

    Anyhow, do you understand what I'm asking for? Can you give me some ideas? Is this type of thing possible?

  7. Hum the start of Schubert's Trout and see if they take it up.

    1. Might try that.

      It may take several questions/exercises to make a good assessment.

      Seeing if they have fundamentalist religious beliefs is probably another good test, although inappropriate for someone I've just met.

    2. Do not do any of that. Ask them about themselves and their lives, and the places where they live and their opinions on things. Then the chance of learning something is increased. You can do your selection of follow up conversations after that.

    3. Attend talks on serious topics at your local library.

      Join your local art museum's booster society. Attend events.

      Join your local university museum's friends group. Attend events, especially lectures on newly published books on obscure features of just about anything.

      Join a writer's group. Take a class through your local adult ed. department.

    4. Ask 'em whether they believe that the pyramids were built as grain silos. If one says "yes" he may be a distinguished neurosurgeon.

    5. New story:

      It turns out, not only did Ben Carson lie about his “violent youth” and Egyptian pyramids, it seems he was never even a neurosurgeon:


  8. Does it correlate with increasing myopia?

    Children have been spending less and less time outside. The environmental changes of less time moving and playing outside, vs. more time sitting focusing one's eyes on a point on a plane mere inches from the nose could influence one's ingrained knowledge of three-dimensional objects.


    The environment influences the phenotype.

    1. ''Environment'', where we live, ALWAYS influence phenotypes as well phenotype ALWAYS will have inner, self or genetic influence. The question is, what is the most strong response*

      my typ, specially in stable environment, living beings. Myopia is not a ''influence of environment'' but a ''organic response'' to this environment change, as happened with inuits when they moved from ice to the urban Canada.

      i ''feel'' ;)

  9. If this paper is correct (about which I am agnostic, not knowing anything about the honesty and competence of the authors) then it looks exactly like what myself and Woodley predicted on the basis of mutation accumulation.

    This was predicted by WD Hamilton some decades ago, and is discussed in Narrow Roads to Gene Land Volume II.

    The main cause of mutation accumulation is assumed to be greatly reduced harshness of natural selection (needed to purge newly occurred plus inherited deleterious mutations of moderate effect, with each generation) since the Industrial Revolution. (This process is termed mutation selection balance.)

    The most significant factor is probably the reduction in stillbirths/ neonatal and child mortality from considerably more than fifty percent pre-1800 to about one percent nowadays).

    http://iqpersonalitygenius.blogspot.co.uk/2013/02/what-are-genetic-causes-of-dysgenic.html and many other posts since.

  10. "myself and Woodley": aw, Bruce, how could you?

  11. @d - It is difficult enough to get my comments posted here - due to some stubborn and persistent software problem; but editing and proof-reading a long comment is far beyond my humble abilities.

    Anyway, who cares (not I - speaking as an ex-journal-editor!) about linguistic clumsiness in science; so long as the intention is honest and the meaning is clear and unambiguous?

    We can't all write luminous scientific prose like Bronowski or Chargaff - not least because we have the (mis?) fortune of being native English speakers of less than genius...

  12. Dear Bruce - avoid the preview button. I think that's what causes the problem.