Thursday, 2 July 2015

Elijah Armstrong replies to JayMan


1) Verbal abilities are probably more relevant to educational attainment than other specific abilities, but g is by far the most relevant. It would be odd if the error only affected verbal ability but not measured g.

Incidentally, the LBC study –– if memory serves –– gave the children two separate IQ tests, one of these the 1937 Stanford-Binet, and Ritchie et al. also controlled for SES in their study of educational effects. Two full-scale IQ tests (though with a strong verbal bias) plus an SES measure jointly compose an immensely reliable composite measure of IQ. Still confounded by differential rates of maturation, of course.

2) Of course those are valid criticisms! But, as Sandra Scarr said of twin studies, the holes don't go straight through. Logically invalid appeal to authority here –– I doubt that any decent intelligence researcher today believes in zero or zero-ish effects of schooling on IQ (you excepted), although they might consider those effects hollow.
I don't want to sound condescending, but you really should read Ceci's 1991 paper on education and IQ.

What a priori reason is there to believe that schooling does not affect IQ? I can think of a few: zero shared environment on adult IQ, but substantial shared environment on total educational attainment; the lack of effects of compensatory education; the lack of effect of school quality on achievement, as measured by Coleman. Good arguments, to be sure. But I do not think they outweigh those I've listed above.

With respect to shared environment, suppose that educational differences in affluent countries account for 10% of total variance in IQ scores (probably too high) and that total years of education exhibit shared environmentality of 20%. Then the total amount of IQ variance that could be explained by education-related shared environment is 2%. (Add to this quality of nutrition and other factors, and you could get more. So 2% is conservative, by my argument. Maybe 5%?) You would probably know better than I whether behavior genetic knowledge can, at the present time, reliably distinguish a 2%/5% from a 0% shared environmental effect. I suspect so, in which case the education-affecting-IQ theory faces a real problem. As you know, though, when behavior genetic studies include families living in genuine poverty, there are inconsistent effects –– sometimes, but not always, the shared environmentality goes up.

A final argument: IQ tests contain obviously scholastic information, vocabulary, arithmetic problems, and so on. How likely is it that education does NOT affect these? We have good evidence, if I am not mistaken, that there is some shared environment effect on educational achievement scores.

3) Kindly post the Danish study. If that replicates, it would suggest adult educational gains to be hollow, perhaps limited to crystallized intelligence or verbal ability (as found by Ritchie et al.).

Suppose that gains do end up generalizing across tests, as with the Flynn effect. Could they still be hollow? Yes, if there are some sources of variance common to all tests but not shared by real-world criteria.

Motivation is one. The relatively rigid and sequential format of "test reasoning", relative to the messier and ambiguous forms of real-world reasoning, are another. (This distinction was drawn by Ulric Neisser, and used by Sternberg in his triachic theory.)

More research! More research!



  1. "IQ tests contain obviously scholastic information, vocabulary, arithmetic problems, and so on. How likely is it that education does NOT affect these?"

    What if the effect is "only up to a point"? In other words, you'd need some modest education to cope with many IQ tests, but extra education thereafter might be of little importance. If people will apply linear regression to their data, such a pattern might be missed.

  2. Sorry, no data – just observation from the testing trenches: Both JayMan & Elijah are right. The answers depend mainly on what the actual items of the ability test are (rather than any pie in the sky theorizing) here’s how it works:

    The recipe: smart committed teachers - & mainly smart peers (!) & the teachers actively & constantly push folks in math, & have a specific active program in vocabulary (caveat - brighter kids gain more, dull kids probably not at all)

    I’ve tested (way too many) kids – some who start out at one school, move to another school, sometimes I test them 3 times through their lives (a few even more – I don’t want to think about it), back to the topic:

    Kids with an exceptional (expensive/private) education get a slightly higher GCA (equivalent to IQ) boost on the DAS-II:
    Because, of the 6 subtests that contribute to the overall score - their 2 verbal subtests will go up by a raw score of 1 or 2 (or even 3 if you’re really bright to begin with) Of the 2 verbal subtests, the vocabulary (“word definitions”) test is affected more - I’ve had dozens of kids from a particularly great private school say “I learned that word during our wordly-wise program!” I’ve also had many say “we learned that in wordly-wise – but I forget what it means!”:) school keeps them in the verbal ball game – which helps those the most who are pre-wired to be good at/like words – there Elijah is right.

    1 of the DAS-II’s nonverbal reasoning subtests will go up by 1 or 2 items (seq./quant. reasoning, which is # patterns – for those who are more facile & less scared with attacking # type problems – they benefit from regular “# boot camp”/math instruction)
    the other nonverbal reasoning subtest (matrices) is less likely to be affected. (almost everybody knows the rules on how to do them now, but not everyone can hang in there long enough to figure out & apply each rule).
    The 2 spatial subtests are unlikely to be affected (schools pretty much ignore spatial – see Wei, Lubinsky, etc. for more).

    Are these increases more than temporary? Well, does good verbal help you learn more verbal? Then maybe you get a few bonus verbal points the rest of your life. & a bonus point or 2 on any # series type task. Does that mean you’re smarter? Depends on what you mean by smarter:) Here I think JayMan is right. Getting some bonus points during your life ON SPECIFIC ITEMS is not going to make you any smarter at age 80.

    Btw, that “school effect” hits the most on skills like phonological awareness, which can be really be wired in hard & heavy. The newer WJ-IV cognitive sadly uses some phonological tasks as part of its overall IQ (“GIA”) Some of that phonological stuff is very exposure based – but some isn’t (when it’s timed, or requires multiple retrievals for each task – then kids with retrieval deficits have problems even with all the rules wired in).

  3. PS - given School's motto basically is:
    "Schools: pretending ability doesn't matter, since 1915!"
    i'm not predisposed to give them the benefit of the doubt.

  4. Let me wrap up this argument this way:

    First, here's the Danish study.

    I think my post The Son Becomes The Father comes into play here.

    There is a (fairly substantial) shared environment effect on educational attainment. But there is no such effect on either IQ or any relevant outcome (like employment or income). This, even if there is an effect of education on IQ test score, it cannot represent a "real" effect on cognitive ability since any such effect doesn't show up in outcomes (a point underscored by the Danish study).

  5. from Elijah Armstrong:
    I would like to see data on the effects of extreme educational deprivation. However, based on the Danish results I am presently willing to accept, as a working hypothesis, that educational IQ gains are confined to a purely verbal or "abstract" domain -- or are even narrower, gains in test-wiseness or something like that.

    panjoomby: Interesting stuff. Do you observe more across-the-board "test wiseness" or comfort with IQ tests with your well-educated examinees?

    1. Abraham Lincoln suffered from extreme educational deprivation, only 1.5 years of grammar school as I recall, then off to work on the river. He became one of the most powerful lawyers in the US, then President.....Yes, anecdotal!

  6. from Elijah Armstrong

    Jason Malloy has an interesting study of Thai farmers on HVGIQ:

    The study finds that years of schooling are a significant determinant of Thai farmers' productivity in multiple regressions; CPM scores, scores on a test of agricultural information, reading comprehension scores, and numeracy scores are not statistically significant. (CPM scores were dreadful, of course. Malloy estimates them around 72 relative to a sample of American farmers.) However, I only skimmed the study, and I can't interpret the regression tables. If the cognitive ability tests were regressed on one another (god forbid) that could explain this weird result.

    I suppose it's also possible that years of schooling are actually a better measure of g in this sample than their diverse sample of four tests, but I doubt it. Malloy finds that the CPM showed low validity in Thailand around the time of the study, and Wicherts et al. established poor validity of Raven's in Africa. But the authors of this study didn't just use the CPM.

    The authors cite this study of Nepalese farmers:

    Jamison, D. T. and P. R. Moock. 1984."Farmer Education and Farm Efficiency in Nepal: The Role of Schooling, Extension Services, and Cognitive Skills," World Development, vol. 12, no. 1. pp. 67-86.

    claiming it finds similar results.

    1. Is there any chance that farmers remove those of their sons who are strong of back and quick of mind quite quickly from school so that they can be put to work? Meantime, they might leave the duller or weaker at school, in hopes that they might at least qualify for a government job.

  7. Elijah is a brilliant lad, and he is going to exert all that brilliance to prove that environment is more important than heredity. If anyone could do it, he could.....but it can't be done.

  8. The fact that IQ raw scores (like pretty much all school exam scores) have inflated vastly through the past century (The Flynn effect), while g has declined substantially (according in the objective and other convergent g-correlated measures discovered by Michael Woodley and myself), confirms that IQ testing is valid comparatively and cross-sectionally - but it not valid longitudinally.

    But there is really no reason to assume that IQ testing would be valid longitudinally - IQ is not, after all, a physiological measurement, and has always been expressed in a comparative form (either as a ratio or in terms of a normal distribution curve -

    Getting an answer right in a test is just *not* an objective measure of cognitive ability - there are many, many ways in which the probability of a correct answer can be influenced.

    In conclusion, IQ tests are not a valid longitudinal measure of g. What they are measuring is a combination of a such a large number of test-score-influences that long term IQ changes (or lack of changes) are probably un-interpret-able.

  9. No reason why Digit Span should not be a good longitudinal measure. The total score does not vary much. Digit Symbol probably the same. Word store, estimated from an extensive vocabulary test might conceivably also be stable.

    1. Word store would work for demonstrating intellectual decline with age, as I always tell whatshername.