Fw: [Upstream] New review of Jensen's The g Factor

["Gerald W. Bracey" <gbracey@EROLS.COM>]

Peter, Quan, anyone:  Comments????
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From: Louis R. Andrews <LRAnd@groupz.net>
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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
>          rushton@julian.uwo.ca
>          http://www.sscl.uwo.ca/psychology/faculty/rushton.html
>          http://www.bookworld.com/rushton
>
>      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
>  animals.
>
>  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
>  Indian).
>
>  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.
>
>  REFERENCES
>
>  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).
>  ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/
>  psyc.99.10.023.intelligence-g-factor.1.jensen
>  http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?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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