Reinventing the Wheel

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The NYT has an article up about how supposedly malleable IQs are by a professor trying to get more money for early childhood education programs. Aside from the arguments about funding a program that is not that effective , the merits of the NYT article are questionable.

Kirp’s argument is based on two studies by the same researcher: Michel Duyme. Before anything is stated about the studies, I’ll point out that while the participants in these studies may be new, the theory and designs are not. Herman Spitz’s masterful work goes over many of these types of studies, and the overall result is not too impressive for those thinking IQ is easily changed. If your educational psychology professor didn’t make that book a required reading, join Questia and read it, or snag it from the local library.

Now on to the NYT article…….

About the first study, Kirp writes:

Regardless of whether the adopting families were rich or poor, Capron and Duyme learned, children whose biological parents were well-off had I.Q. scores averaging 16 points higher than those from working-class parents. Yet what is really remarkable is how big a difference the adopting families’ backgrounds made all the same. The average I.Q. of children from well-to-do parents who were placed with families from the same social stratum was 119.6. But when such infants were adopted by poor families, their average I.Q. was 107.5 – 12 points lower. The same holds true for children born into impoverished families: youngsters adopted by parents of similarly modest means had average I.Q.’s of 92.4, while the I.Q.’s of those placed with well-off parents averaged 103.6. These studies confirm that environment matters – the only, and crucial, difference between these children is the lives they have led.

Darth Quixote has already deeply delved into this study, and there is no need to repeat him here. I will add:

  • the design was non-experimental, post-test only. While these designs have merit, to infer causality is tenuous as the adoptees’ IQ could easily have fit the same pattern before adoption. Moreover, since there was no randomness in the adoption process, we have no idea as to why the children were placed where they were.
  • the researcher’s did not test to see if the instrument they were using was functioning the same across comparison groups. A (good) way to check this Multigroup confirmatory factor analysis (e.g.,), but with the n so small, it is difficult to do.1 As a proxy, I checked for equality of covariances: B+ vs B-: not significantly different; A+ vs A-: not significantly different; B+A+ vs B-A-: significantly different! (chi-square: 154.79, df= 55, p < .0001). This could mean multiple things. Two that come to mind are: a) the B-A- group's pattern of cognitive functioning has not matured at the same rate as the B+A+ group, so give them some time and it may converge. b) the B- kids were placed into the A- home for a specific reason (i.e., they had some type of deficit that made A+ parents pass on them).
  • So where does leave us? Capron and Duyme sum it up best:

    Although these findings clearly indicate that the biological parents’ background contributes to observed differences in IQ between extreme groups, as does that of adoptive parents, more detailed interpretation is difficult (p. 553)

    which is a far cry from Kirp’s interpretation:

    the only, and crucial, difference between these children is the lives they have led.

    About the second study, Kirp writes:

    A later study of French youngsters adopted between the ages of 4 and 6 shows the continuing interplay of nature and nurture. Those children had little going for them. Their I.Q.’s averaged 77, putting them near retardation. Most were abused or neglected as infants, then shunted from one foster home or institution to the next.

    Nine years later, they retook the I.Q. tests, and contrary to the conventional belief that I.Q. is essentially stable, all of them did better. The amount they improved was directly related to the adopting family’s status. Children adopted by farmers and laborers had average I.Q. scores of 85.5; those placed with middle-class families had average scores of 92. The average I.Q. scores of youngsters placed in well-to-do homes climbed more than 20 points, to 98 – a jump from borderline retardation to a whisker below average. That is a huge difference – a person with an I.Q. of 77 couldn’t explain the rules of baseball, while an individual with a 98 I.Q. could actually manage a baseball team – and it can only be explained by pointing to variations in family circumstances.

    One has to do some digging elsewhere, but the study he is referring to is from PNAS. Since the study is free to read, I’ll only go over the major points:

  • The research team picked children/teenagers who met five criteria: They had all been (1) neglected and/or abused during infancy, having been definitively removed from their biological family by court order after judicial procedures; (2) placed in many foster families and/or institutions before adoptive placement; (3) had an IQ 60 in the year preceding adoptive placement; (iv) aged 4-6 at the time of the adoptive placement and (v) aged 11-18 and being raised by the same two adoptive parents at the time of the second IQ test (i.e., 5-14 years with same adoptive parents)
  • The original IQ test was either a) the first or second edition of the Stanford Binet (their wording and reference date makes it hard to discern), b) the original Bayley Scale of Infant Development, or c) “other French tests of Intelligence”. The post-adoption IQ was either the WAIS or the WISC-R.
  • The Children/teenagers were classified into one of three groups based on adoptive father’s occupation: High, Middle, or Low
  • There was a universal gain in IQ scores for all participants, averaging 13.88 points.
  • There was a (range restriction corrected) correlation of 0.67 between IQs before and after adoption, which “indicates a degree of stability close to the stability found in longitudinal studies of biological children who have not undergone an environmental change. . . Thus, on the basis of IQ at the end of the preschool period, the results show that there is a moderate stability for rank. This is a near-universal finding.
  • As to a critique, first the selection criteria is loaded. No one with any sense about them would think that being abused/neglected from birth so bad that the legal system has to intervene would not decrease cognitive functioning. This is not at all what is meant when discussing “Average Expectable Environment.” So right off the bat we know that these kids are not at all the same as a regular Joe (or Jane) off the street who has Borderline IQ. Thus, right off the bat we would expect that after any semblance of stability, the kids’ cognitive functioning would improve (i.e., return to its normal state).

    Second, while there is some difference between the IQs across groups, it isn’t major (max: Low SES PIQ vs High SES PIQ, d = .9 [r2=.17]; min: Low SES VIQ vs. High SES VIQ, d=.5 [r2=.06]), indicating SES explains somewhere between 6 and 17 percent of the variance in post-adoption IQ scores. While there is definitely an effect, given the extreme nature of the study’s categories, it does not appear to be much of one.

    Third, it is very difficult to say with much certainty that IQ scores from scale, developed with one set of theoretical guidelines and one set of 1950s norms are directly comparable other IQ scores from a different scale, developed with a totally different theoretical orientation that uses a set of 1970s/1980s norms. This is even more so when the Bayley scale is used. For those of you that have given the Bayley (all 2 of you!), you know it is an extreme pain to administer and that it is about as unlike the Wechsler instruments as you can find a test that still measures cognitive ability.

    Fourth, while there was an overall mean increase in IQ, in addition, there was a universal gain in variance (stnd. dev. increased approx 9 IQ points). Thus, assuming that the before and after IQs were directly comparable, the majority of the scores fell into these ranges:

    95% Range of IQ (i.e., -/+ 2 SD)


    Low SESHigh SES

    A few things to notice. 1. There were at least some kids in both categories who, pre-adoption, were in the average range. Given the stark conditions of their pre-adoption upbringing, that is amazing – and likely has little to due with a nurturing environment. 2. There were at least some kids in both categories who, post-adoption, were in the Mild to Moderately Deficient range. Meaning – they still were classified as MR. If the environment is so powerful, why didn’t their IQ rise also? 3. It is a fair assumption that even the Low SES households were much better off for the kids than their abusive/neglectful original home. If the environment is so powerful, then why are some children doing worse, IQ-wise, post-adoption?

    Fifth, buried in the next to last paragraph of the study, we find this statement:

    This study shows that stability for rank can be found following a marked environmental change after 4 years of age regardless of the SES of adoptive families. The factors explaining this stability are undoubtedly different from those explaining the gains in mean IQs.

    Interpretation: the worst performers before the adoption tended to be the worst performers after the adoption. The only thing that happened was a linear transformation of scores (i.e., post-score ≈ a*pre-score + b) across all SES groups, which could be due to many things, including: changing IQ scales and/or many years of living in an “average expectable environment.”

    So, what we end up with is a picture much more complex and intricate than Kirp allows. What we can definitely conclude is that abusing or neglecting your children so bad that the government has to take them away tends to produce lower IQs (although some kids will still be in the average range), but was this really in question? What we can also conclude is that for some children in the MR range, adoption into high SES environments will not significnalty improve thier IQ. If the environment is so powerful to change cognitive abilities, then how did this happen? Last, I think we can conclude that Kirp’s attempt to glorify the ability of the environment to change IQ is not much more than the wheel, reinvented.

    [1.] I did it using the bootstrap feature in AMOS. I can go into more detail by email or in the comment box.


      What we can defiantly conclude is that abusing or neglecting your children so bad that the government has to take them away tends to produce lower IQs (although some kids will still be in the average range)
      (Emphasis added) 
      Why would we want to be defiant about it?

    2. The study you link to suggests that Head Start is of limited effectiveness because other environmental factors eventually swamp its influence, therefore supporting David Kirp’s argument that IQ manifestation is heavily influenced by socio-cultural, rather than innate, variables. Do you have a criticism of the study’s research design or some other reasons why we should discount it?

    3. Many, many apologies. I didn’t hit the “read the rest of the post” link.

    4. So a less snide comment: 6-17%, particularly at the upper range, is still a fairly significant change in cognitive performance as measured by the tests in question. Given that the debate is not, at least among sane people, about whether cognitive capacity is heritable, but about the degree to which environmental factors can influence cognitive performance, this still seems like a fairly significant rebuttal of strong (in these relative terms) determinism.

    5. Why would we want to be defiant about it? 
      Stupid spell checker can’t read my mind. Thanks for the catch. I changed it.

    6. 6-17%, particularly at the upper range, is still a fairly significant change in cognitive performance as measured by the tests in question. 
      But these were not run of the mill MR children. They were from extreme circumstances. So this is likly a likly a cap as far as shared environments can influence IQ outcomes, and not really that applicable to folks from “normal” environments.

    7. you can environmentally influence IQ all the way to brain death. what’s not been well demonstrated is any way to cause a lasting increase in g among children raised in better-than-criminal environments. 
      the only people i’ve read claim to do anything like that is The Abecedarian project

    8. the only people i’ve read claim to do anything like that is The Abecedarian project 
      Claim is the key word. 
      Spitz, H. H. (1992). Does the Carolina Abecedarian Early Intervention Project prevent sociocultural 
      mental retardation? Intelligence , 16, 225 
      Spitz, H. H. (1993). Early educational intervention research and Cronbach’s two disciplines of scientific psychology. Intelligence , 17 , 251-256.

    9. alex, that was my guess, but i’d never seen the responses

    10. After reading Jensen’s 1969 paper I am even more strongly of the opinion that the only way to access the approximately 20% variance attributable to the environment is through better pre- and peri-natal care for children from lower SES environments. 
      Unfortunately, certain strong lobby groups have opposing interests.

    11. Why does it follow that this is the upper limit (of how variation in environmental factors shape scores on IQ tests)?  
      Anyway, I’m confused, because first you argued that the study involved contained numerous methodological flaws–lack of randomization, endogeneity issues, and so forth–and then you assert that this is the upper limit of environmental influence. How does that follow?

    12. Anyway, I’m confused… 
      I explicitly stated, assuming that the before and after IQs were directly comparable. That is an assumption, which I think is not necessarily tenable; but, for the sake of argument, if it were so, then I offered the fourth branch of the critique. 
      That being said, the r2 values (in the second branch of the critique) had nothing to do with pre-post testing. It had to do with post testing only and its relation to SES. 
      They are two seperate. independent critiques of the article (well, not so much the article, per se, but the blantent misrepresentation of it by the NYT)

    13. The cumulative (environmental) Flynn Effect is over 20 IQ points. It may be argued that this only affects IQ test results and not the mystical quality g, but that’s too subtle for me.

    14. Sharpe: ?After reading Jensen’s 1969 paper I am even more strongly of the opinion that the only way to access the approximately 20% variance attributable to the environment is through better pre- and peri-natal care for children from lower SES environments.? 
      I strongly agree with your main point. Avoiding harmful substances, breast feeding, and supplementing with fish oils, vitamins, and minerals should improve IQ. 
      However, I believe that the potential improvement is greater than a part of 20% environmental variance. 
      First, I suspect the 20% number does not represent a population of poor blacks. I?d expect the environmental contribution to be higher in that subpopulation. 
      Second, the 20% number is only what has been measured in the past. Applying the best information known to date could raise the bottom scores by more than 7 points. As brain function and development are better understood, more effective interventions will be possible. So future improvements are not constrained by past statistics. 
      I?m hopeful that future advances in nutrition, medicine, biotech, and education will significantly increase intelligence.

    15. If a population experiences a common environmental change across SES and race, then snapshot studies of differences due to environment may not show the change while comparisons between generations would (Flynn Effect)? 
      Mother?s health and nutrition may have lasting effects: 

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