Fw: [Upstream] New review of Jensen's The g Factor
- Subject: Fw: [Upstream] New review of Jensen's The g Factor
- From: "Gerald W. Bracey" <gbracey@EROLS.COM>
- Date: Mon, 15 Nov 1999 15:26:28 -0500
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Peter, Quan, anyone: Comments????
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From: Louis R. Andrews <LRAnd@groupz.net>
Sent: Monday, November 15, 1999 2:45 PM
Subject: [Upstream] New review of Jensen's The g Factor
> psycoloquy.99.10.044.intelligence-g-factor.3.rushton Mon Nov 15 1999
> ISSN 1055-0143 (16 paragraphs, 12 references, 253 lines)
> PSYCOLOQUY is sponsored by the American Psychological Association (APA)
> Copyright 1999 J. P. Rushton
> THE "JENSEN EFFECT" AND G VECTOR ANALYSIS
> Book Review of Jensen on Intelligence-g-Factor
> J. Philippe Rushton
> Department of Psychology
> University of Western Ontario
> London, Ontario
> N6A 5C2 Canada
> ABSTRACT: Jensen's method of correlated vectors is the jewel in the
> crown of his 30-year research on the nature of Spearman's g.
> Significant correlations between g-factor loadings and other
> variables, "Jensen Effects," are discussed here in relation to
> Black/White differences.
> 1. Sir Francis Galton's (1822-1911) book "Hereditary Genius" (1869)
> predated by exactly one century the famous 1969 Harvard Educational
> Review article that led "Jensenism" to be defined as "the theory that
> an individual's IQ is largely due to heredity, including racial
> heritage" (Random House; Webster's Unabridged). Jensen's (1969) review
> of the evidence that IQ is heritable and that genetic factors are
> involved in the Black-White IQ gap had enormous impact. Nonetheless,
> Jensen's main scientific goal has been to understand the nature of
> intelligence rather than race differences as such.
> 2. The jewel in the crown of Jensen's legacy is his development of the
> method of correlated vectors. A "vector" of scores is a set that
> possesses both direction and quantity. Jensen has applied the method of
> correlated vectors (fully explicated in Appendix B of Jensen 1998) to
> many collections of variables and shown that the vector of a test's g
> loadings is the best predictor not just of that test's correlation with
> scholastic and work-place performance, but with brain size, brain pH,
> brain glucose metabolic rate, average evoked potential, reaction time,
> and other physiological factors, hence establishing the biological (as
> opposed to the mere statistical) reality of g.
> 3. Consider the correlation between IQ and brain size. Numerous modern
> studies confirm that the correlation between IQ and head circumference
> measured by tape is about 0.20 and that between IQ and brain volume
> measured by Magnetic Resonance Imaging is about 0.40 (Jensen 1998,
> Chapter 6). Using the method of correlated vectors shows the
> correlation with g to be between 0.60 and 0.70! Jensen's method has
> distilled the essence of intelligence
> 4. In a recent special issue of the journal INTELLIGENCE honoring
> Jensen's accomplishments, I proposed that when a significant
> correlation occurs between the two vectors, the result be called a
> Jensen Effect (for that X variable), because otherwise there is no name
> for it, only a long explanation of how the effect was achieved
> (Rushton, 1998). The Jensen Effect can be seen whenever there is a
> significant correlation between the vector of the sub-tests' g loadings
> and the vector of the same sub-tests' loadings on variable X (where X
> is some other, usually nonpsychometric, variable).
> 5. Jensen Effects are not omnipresent and their absence can be as
> informative as their presence. An important case of the absence of the
> Jensen Effect is that of the secular increase in test scores. Simply
> stated, the "Flynn Effect" is not a "Jensen Effect." Principal
> components analyses show that whereas the IQ gains over time on the
> WISC-R and WISC-III do cluster (suggesting they are a reliable
> phenomenon), these are independent of g factor loadings, the cluster of
> Black-White differences, and of inbreeding depression scores (Rushton,
> 1999). These results provide convergent and discriminant validity for
> the "Jensen Effect" and disconfirm Flynn's hypothesis that the "massive
> IQ gains over time" found in several countries prove that the
> Black-White differences in IQ are environmental in origin.
> 6. The g Factor, Jensen's monumental tome on the reality of g,
> actually has little to do with race, as such. The first five chapters
> deal with the intellectual history of the discovery of g and various
> models of how to conceptualize intelligence. Other chapters deal with
> the biological correlates of g (excluding race), its heritability, and
> its practical predictive power. The fact that psychometric g has many
> physical correlates proves that it is not just a statistical reality.
> Among biological variables, g loads on heritability coefficients
> determined from twin studies and inbreeding depression scores
> calculated in children born from cousin-marriages. G is related not
> only to brain size measured by Magnetic Resonance Imaging (MRI), but
> also to brain evoked potentials, and intracellular brain pH levels. G
> is a product of human evolution and is also found in non-human
> 7. Despite the fact that The g Factor is not primarily about race,
> Jensen's discussion of g and race will strike many as being its central
> theme. All the issues Jensen dared to voice in 1969 are still with us
> today. Indeed, much of the opposition to IQ testing and heritability
> research would probably disappear if it were not for the stubborn and
> unwelcome fact that, despite extensive programs of intervention, the
> mean Black-White difference in g does not diminish. Chapter 11 of The
> g Factor fully documents that, on average, the American Black
> population scores below the White population by about 1.2 standard
> deviations (equivalent to 18 IQ points).
> 8. The book describes how the difference between Blacks and Whites in
> average IQ scores has scarcely changed over the past 80 years. It can
> be observed as early as three years of age. Controlling for overall
> socioeconomic level only reduces the mean difference by 4 IQ points.
> Culture-fair tests tend to give Blacks slightly lower scores, on the
> average, than more conventional tests, as do non-verbal tests compared
> with verbal tests, and abstract reasoning tests compared with tests of
> acquired knowledge. On average, Blacks also score 1 standard deviation
> below Whites in academic achievement throughout the period from grades
> 1 through 12 (and also considerably below all other disadvantaged
> minorities tested: Puerto Rican, Mexican-American, and American
> 9. The g Factor does not draw back from its most controversial
> conclusions -- that the average difference in IQ between Blacks and
> Whites has a substantial hereditary component, and that this difference
> has important societal consequences. Jensen Effects encompass
> Spearman's (1927) specific hypothesis about the heritability of the
> Black-White IQ gap. The "Spearman-Jensen hypothesis" (as Travis
> Osborne, 1980, dubbed it), that Black-White IQ differences are greatest
> on the g-factor, is tested by first extracting the g factor from a
> variety of cognitive tests (a vector of scores), and then relating
> these scores to the mean Black-White differences on those same tests (a
> second vector of scores). Early tests of this hypothesis were
> summarized in BEHAVIORAL AND BRAIN SCIENCES and responded to with open
> peer commentary (Jensen, 1985, 1987).
> 10. Jensen's book reviews the results of numerous subsequent
> investigations of the Spearman-Jensen hypothesis using a wide variety
> of psychometric tests administered to large representative samples of
> Whites and Blacks. Chapter 11 describes the results from 17 independent
> data sets on a total of nearly 45,000 Blacks and 245,000 Whites derived
> from 171 psychometric tests. G loadings consistently predict the
> magnitude of the Black-White difference (r = +.63). The rank
> correlation between the g loadings and the Black-White differences is
> +.71 (p <.05).
> 11. These g related population differences are not due to factors such
> as the reliability of the test, social class differences, or
> tautologies based on some inevitability of factor analysis. Indeed, it
> is not even universally true that all groups that differ, on average,
> in their overall score on a test battery will conform to the
> Spearman-Jensen hypothesis. In South Africa, although the nearly 1
> standard deviation difference between Whites and East Indians showed no
> correlation between g loadings and standardized mean differences, the 2
> standard deviation difference between Whites and Blacks showed a
> correlation of +.62.
> 12. The Spearman-Jensen hypothesis applies even to the g factor
> extracted from performance on elementary cognitive tasks. In some of
> these studies, 9-to-12-year-olds are asked to decide which of several
> lights is illuminated and move their hand to press a button that turns
> that light off. All children can perform the tasks in less than one
> second, but children with higher IQ scores perform faster than do those
> with lower scores, and White children, on average, perform faster than
> Black children. The correlations between the g loadings of these types
> of reaction time tasks and the Black-White differences range from +.70
> to +.81.
> 13. When Jensen examined East Asian-White comparisons using these same
> reaction time measures the direction of the correlation was opposite to
> that in the Black-White studies. On average, East Asians scored higher
> in g than do Whites. No one so far seems to have looked at East
> Asian-White differences on conventional psychometric tests as a
> function of their g-loadings. From the study just mentioned, however,
> Jensen's prediction is clear: A Jensen Effect should be found
> indicating an East Asian advantage.
> 14. Chapter 12 presents Jensen's technical arguments for why he
> believes that Black/White differences are about 50 percent heritable.
> He emphasizes the fact that it is precisely those components of
> intelligence tests that are most heritable and that most relate to
> brain size which most profoundly differentiate Blacks from Whites.
> Direct evidence comes from transracial adoption studies carried out on
> Korean and Vietnamese children adopted into White American and White
> Belgian homes. Though many had been hospitalized for malnutrition,
> prior to adoption, they went on to develop IQs ten or more points
> higher than their adoptive national norms. By contrast, Black and
> Mixed-Race (Black-White) children adopted into White middle-class
> families typically perform at a lower level than similarly adopted
> White children. In the well known Minnesota Transracial Adoption
> Study, by age 17, adopted children with two White biological parents
> had an average IQ of 106, adopted children with one Black and one White
> biological parent averaged an IQ of 99, and adopted children with two
> Black biological parents had an average IQ of 89.
> 15. The g Factor (Chapter 6) reviews the literature that found that the
> brain-size/IQ relation was most clearly shown using Magnetic Resonance
> Imaging (r = .44 across eight separate studies). Chapter 12 cites my
> own review of the literature (Rushton & Ankney, 1996) that documents
> the three-way Asian/White/Black gradient in brain size established by
> aggregating data from studies using four kinds of measurements: (a) wet
> brain weight at autopsy; (b) volume of empty skulls using filler; (c)
> volume estimated from external head sizes; and (d) volume estimated
> from external head measurements and corrected for body size. East
> Asians and their descendants average about 17 cm3 (1 in3) larger brain
> volumes than do Europeans and their descendants, whose brains average
> about 80 cm3 (5 in3) larger than do those of Africans and their
> descendants. Jensen calculated an "ecological" correlation (widely used
> in epidemiological studies) of +0.99 between median IQ and mean cranial
> capacity across the three populations of "Mongoloids," "Caucasoids,"
> and "Negroids."
> 16. The g Factor is a gold mine of information, a sourcebook for
> researchers, and a volume that critics as much as supporters have an
> obligation to read.
> Flynn, J. R. (1999) Searching for justice: the discovery of IQ gains
> over time. American Psychologist, 54:5-20.
> Galton, F. (1869) Hereditary genius. London: Macmillan.
> Jensen, A. R. (1969) How much can we boost IQ and scholastic
> achievement? Harvard Educational Review, 39:1-123.
> Jensen, A. R. (1985) The nature of the black-white difference on
> various psychometic tests: Spearman's hypothesis. Behavioral and
> Brain Sciences, 8: 193-263.
> Jensen, A. R. (1987) Further evidence for Spearman's hypothesis
> concerning the black-white differences on psychometric tests.
> Behavioral and Brain Sciences, 10: 512-519.
> Jensen, A. (1998) The G Factor: The Science of Mental
> Ability. Praeger
> Jensen, A. (1999) Precis of: "The G Factor: The Science of Mental
> Ability" PSYCOLOQUY 10(23).
> Osborne, R. T. (1980) The Spearman-Jensen hypothesis. Behavioral and
> Brain Sciences, 3:351.
> Rushton, J. P. (1998) The "Jensen Effect" and the "Spearman-Jensen
> hypothesis" of Black- White IQ differences. Intelligence, 26: 217-225.
> Rushton, J. P. (1999) Secular gains in IQ not related to the g factor
> and inbreeding depression unlike Black-White differences: A reply to
> Flynn. Personality and Individual Differences, 26: 381-389.
> Rushton, J. P. & Ankney, C. D. (1996) Brain size and cognitive ability:
> Correlations with age, sex, social class, and race. Psychonomic
> Bulletin and Review, 3: 21-36.
> Spearman, C. (1927) The abilities of man: Their nature and measurement.
> New York: Macmillan.
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