A few weeks ago, I have written a review of his book:
http://humanvarieties.org/2014/09/21/mhs-book-review-of-deafness-deprivation-and-iq-braden-1994/

And followed by a review of the studies since the book has been published:
http://humanvarieties.org/2014/09/21/the-study-of-deaf-people-since-braden-1994/



Have you read it, and do you think ?

If I have to give a quick summary, I will say that chapters 4 and 5 are very important. You have some evidence that nonverbal IQ is not biased against deaf children and is probably measure invariant, while verbal IQ is not. There is for example no cumulative deficit effects on nonverbal measures, which showed to be robust to cultural deprivation, while verbal IQ is very sensitive (1 SD gap between deaf and hearing groups).

Braden has concluded that nonverbal IQ is not affected by cultural bias, and for this reason, nonverbal IQ is a better approximate of intelligence than is verbal IQ, despite factor analyses showing that verbal tests have higher factor loadings. Although for evidence that Gc and Gf have similar factor loadings, see Ashton & Lee (2006). Regardless, I believe Braden is right, and that cultural theories can't explain group differences in IQ. I don't think even one of them is relevant.

The claim that nonverbal IQ is less culturally loaded, and is a better approximate of g, is interesting, when we think about the Flynn effect, which is much stronger in nonverbal IQ than in verbal IQ tests, even though it is suspected that the Flynn effect is due to environments.

I don't think the Flynn effect contradicts Braden's conclusion that verbal IQ is more subjected to cultural shifts. The causes behind the Flynn effect is not even clear at all. However, we know that the IQ gains have no predictive validity, at least for high-ability persons (see Flynn, 1987, pp. 187-188), and consequently is probably unrelated to intelligence gains. It is, thus, premature to claim it's an environmental effect, especially, if we are unable to detect what are these environments responsible for the Flynn gains.

In particular, there is one kind of studies I would like to see more often. I have written :

Braden next considered the additive and non-additive genetic models. The fact that nonverbal IQ is little affected by large environmental shift implicated in deafness suggests that most variation in nonverbal IQ comes from additive genetic effects (p. 173). Braden (pp. 175-176) cited a study by Paquin (1992) which has directly tested the genetic hypothesis. The correlation between deaf parents and deaf children in nonverbal IQ was close to the predicted relationship of 0.50. Thus, with regard to deaf children with deaf parents, the additive genetic hypothesis is tenable.

The study is dated now, but this is the only one available. That's unfortunate. I think it deserves better attention.

Unfortunately, there are only two studies on ECTs, and both are done by Braden.

Braden’s (1987) earlier study showed that deaf children of deaf parents are faster (in movement times) than deaf children of hearing parents, who in turn are faster (in movement times) than normal hearing children on RT tasks. This implies that speeded, psychomotor intelligence tests (i.e., performance tests of intelligence) may produce higher IQs for deaf people than nonspeeded intelligence tests (i.e., motor-free, untimed IQ tests). Hearing (HC) and deaf children of hearing parents (HP) have equal RTs but deaf children of deaf parents (DP) deaf have faster RT. Their raw scores on Raven SPM are, respectively, 50.31, 45.71, 47.16. This implies that hearing children have an advantage on nonverbal IQ but not on RT. Braden (1987) suspected the reason behind the lower RSPM score is that the test was untimed; I have calculated the d gap between hearing and deaf children of deaf parents, which was about 5 IQ points. As Braden (1987, p. 265) noted, it was empirically found that deaf people have a deficit in information processing tasks requiring strategy and metastrategy (coordination of strategies) skills, which are learned from others, and, as a result, make poor choices about which problem-solving strategies to use, when the tests do not reward speed (of completion). Finally, Braden (1987) also found that exposure to sign language (ASL) is correlated with faster MT (r=0.180). The reason could be that the genetically deaf (e.g., DP) acquire above-average motor dexterity because dexterity and speed are practiced via the repeated and consistent use of sign language (pp. 132-133), which is ultimately transferred to performance IQ tests because they typically reward rapid and dexterous manipulation of materials. That is consistent with the finding that the genetically deaf have above-average PIQs but average or slightly below-average IQs on motor-free nonverbal tests. This view is based on the suggestion that deaf people compensate for their hearing loss by developing other skills, e.g., psychomotor. In that case, IQ tests that reward speed might provide inaccurate estimates of intelligence, although there is no good evidence that deaf people could develop such skills. In fact, orthopedic, visual, and gross motor disabilities are more prevalent among deaf people than they are among normal-hearing people (pp. 132-133). The greater prevalence of dysfunction in vision and motor skills is attributed to organic, rather than environmental, causes.

But Braden apparently changed his views in Braden et al. (1994). The authors found that deaf children (n=21) have lower scores than hearing children (n=21) on a motor-reduced nonverbal IQ test (MAT-SF) but also completed the test more quickly, even though they had similar WISC-III PIQ scores. Both groups had similar movement time (in median MT and SD of MT) in two nonverbal SIP paradigms (Odd-Man-Out and Hick). Deaf children made more errors on the Odd-Man-Out but probably not on the Hick. They argue that the best explanation is that deaf children are more impulsive, i.e., they initiate responses more quickly because they engage in less anticipation and planning. But this perspective is credible only if MT is equal in both group; this is the case in Braden et al. (1994) but not Braden (1987). So, the issue is not resolved. On the other hand, if impulsivity artificially reduces the IQ of deaf in motor-reduced nonverbal tests, their true IQ level is closer to 100 than to 95.

As for people with William syndrome, it's different. Braden used deaf people to examine the impact of cultural deprivation on the IQ of people who lack the culture of the dominant group, a cultural baggage that is relevant to the test. He said that verbal and nonverbal IQ are so different in their response to cultural deprivation that we should stop thinking they are the same thing. Nonverbal IQ may have (almost) all the characteristics of a fair test. I think that's what he believes.

A few weeks ago, I have written a review of his book:
http://humanvarieties.org/2014/09/21/mhs-book-review-of-deafness-deprivation-and-iq-braden-1994/

And followed by a review of the studies since the book has been published:
http://humanvarieties.org/2014/09/21/the-study-of-deaf-people-since-braden-1994/

Your review was well written and comprehensive; I didn't comment on it as I had not much to say. I had looked into the issue myself earlier. One thing, I might note, is that I found a fairly consistent anti-Jensen Effect of performance subtests; thus, I find it odd that measurement invariance would hold -- though there might be great variability in results depending on the sample and the magnitude of the differences.

You refer to what you did here. But you make the same confusion as lot of people using MGCFA. They wrongly believe if MI is rejected, it says anything about Spearman's hypothesis (SH). They are unrelated. Like I said to you before, it's not your fault, or their fault. It's the fault of Wicherts and colleagues, who said explicitly that if MI is rejected, there is no latent gains. This statement is wrong in the way it is said, and has caused lot of researchers to wrongly believe that MI = Jensen effect. My answer is : no, no and no.

The only way to test SH by way of MGCFA is to do MGCFA by incorporating the 2nd-order latent factor, like Dolan (2000) did. But these people who use MGCFA for testing Flynn gains don't use Dolan's method. And of course, people who use MGCFA for testing MI on hearing/deaf people don't use Dolan's method. But most importantly, you cannot test SH by answering the question of whether MI hold or not. You test SH by looking at model fit. If the model with g has better fit than all the models without g, you have proved the g model to be the best model. That's how you test SH. Like I said before, in the Dalliard's article, that's a different way to test SH, because MCV looks at the correlation, but does not (and probably cannot) incorporate other models.

Anyway, measurement invariance is a nice tool to see if the environmental hypothesis is strong or not. Like I said in the second link, maybe MGCFA has the same problem as all DIF methods : which is, the ipsitivity problem.

But this is not all there is to say. I remember the other day I have looked around and see if there is any replication of the study discussed in Braden's (1994) book. A study (Paquin 1992) saying that the heritability among deaf people is not different than in normal population, exactly as predicted by the genetic hypothesis.

Braden next considered the additive and non-additive genetic models. The fact that nonverbal IQ is little affected by large environmental shift implicated in deafness suggests that most variation in nonverbal IQ comes from additive genetic effects (p. 173). Braden (pp. 175-176) cited a study by Paquin (1992) which has directly tested the genetic hypothesis. The correlation between deaf parents and deaf children in nonverbal IQ was close to the predicted relationship of 0.50. Thus, with regard to DP, the additive genetic hypothesis is tenable. Unfortunately, there seems to be no other studies of this kind with or without other deaf groups. Paquin (1992) has also tested the patterns of regression to the mean. It was expected that deaf children will regress to the mean (population) to the same extent as the normal-hearing children (i.e., half the distance from midparent IQ to the population mean). The result is not robust. The IQs of the deaf children were only slightly lower than their deaf parents.

I wonder why geneticists don't use deaf sibling samples to make that analysis, and see if the heritability is different than in the normal population.