The Latest On Intelligence

The Latest On Intelligence
danielwillingham.com

I suspect one could find papers contradicting each of these points from very well respected scientists within the field. I haven’t the time to review each one right now, but as for the narrowing of the black-white difference, Rushton and Jensen question it:

>“Dickens and Flynn (2006, this issue) challenge our hypothesis. They claim that ‘‘no one can really trace the Black-White IQ gap in the United States back to its origins’’ (p. 913) and that in the United States, Blacks have gained ‘‘4 to 7 IQ points on non-Hispanic Whites between 1972 and 2002’’ (p. 913). But to maintain that ‘‘no one can really trace the . . . gap back to its origins,’’ Dickens and Flynn had to sidestep our citation of Shuey’s (1966) review of the literature, which shows that Black White IQ differences in the United States have remained at 15 to18 points, or 1.1 standard deviations, for nearly a century. For example, she found 23,596 Black draftees in World War I (1917)had an IQ of 83 (vs. 100 for Whites), with a Black overlap of the White mean of 13%. For recent data, we cited the meta-analysis by Roth, Bevier, Bobko, Switzer, and Tyler (2001), which also shows a mean difference of 1.1 standard deviations (range of 0.38 to 1.46 standard deviations, depending on the test’s g loading), based on 6,246,729 individuals from military, corporate, and higher-education samples. Roth et al. found any narrowing of the gap was ‘‘either small, potentially a function of sampling error . . . or nonexistent for highly g loaded instruments’’ (p. 323, italics added).

>To claim a 4- to 7-point gain for Blacks, Dickens and Flynn chose three independent tests showing medium gains (the Wechsler, Stanford-Binet, and Armed Forces Qualification tests) and relegated to their Appendix B four or more tests showing lesser gains. They excluded the Wonderlic Personnel Test, which they acknowledge showed a gain of only 2.4 points for Blacks between 1970 and 2001. (Dickens and Flynn suggest that more ‘‘high quality’’ Whites than Blacks had taken the test.) They excluded the Kaufman Assessment Battery for Children (K-ABC), which Murray (2005) described as showing a loss of 1 IQ point for Blacks between 1983 and 2004. (Dickens and Flynn say the data contained an inflated standard deviation.) They excluded the very g-loaded Woodcock-Johnson test, which Murray (2005; whom they cite) described as showing the conventional gap of 1.05 standard deviations for the third (2001) standardization sample. (Dickens and Flynn say the Blacks were an unrepresentative ‘‘subsubsample.’’) They also excluded the Differential Ability Scale, which in Lynn’s (1996) analysis (which they cite) showed a maximum gain of 1.83 IQ points for Blacks between 1972 and 1986. (Dickens and Flynn say the sample lacked ‘‘quality.’’) To be compelling, however, researchers must take the totality of available evidence into account (Gottfredson, 2005). Even the tests Dickens and Flynn did analyze do not support their conclusion. The alleged gain of 4 to 7 points is from a ‘‘projected’’ trend line based on a small IQ rise per year multiplied by more years than are in the data using unclear procedures (see the additional appendix in the Web site they refer to). Simple arithmetic applied to the data in their Table A1 shows a mean gain for Blacks of only 3.44 IQ points, from 86.44 to 89.88

If you’d like to see an accurate survey of what experts in the field believe, you’ll have to settle for a 25 year old survey, albeit one very well done.[3]

Tl;dr the points made represent one side of the field, and are not a consensus of intelligence researchers.

[1]http://en.wikipedia.org/wiki/Mainstream_Science_on_Intellige... [2] http://menghusblog.files.wordpress.com/2012/01/the-totality-... [3] http://en.wikipedia.org/wiki/The_IQ_Controversy,_the_Media_a...

Nisbett, R. E., Aronson, J., Blair, C., Dickens, W., Flynn, J., Halpern, D. F., & Turkheimer, E. (2012, January 2). Intelligence: New Findings and Theoretical Developments. American Psychologist, 67, 130-159.

http://psychology.msu.edu/pers_hambric3/PSY493%20Spring%2020...

Daniel Willingham reviews in the submitted post, and the paper is a joint review article on the last decade and a half of research on human intelligence by an all-star group of researchers.

After edit: I see other comments are asking about what the research shows about genetic influences on IQ and environmental influences on IQ. Here is some FAQ information on that, originally part of another comment I posed here on HN:

The researchers in the Behavior Genetics Association are making increasingly cautious statements about genetic influence on human behavioral traits as more data are amassed. Here are some of the latest statements by some of the leading researchers.

Turkheimer, E. (2012). Genome wide association studies of behavior are social science. In K. S. Plaisance & T.A.C. Reydon (Eds.) Philosophy of Behavioral Biology (pp. 43-64). New York, NY: Springer.

http://people.virginia.edu/~ent3c/papers2/Turkheimer%20GWAS%...

"If the history of empirical psychology has taught researchers anything, it is that correlations between causally distant variables cannot be counted on to lead to coherent etiological models."

Johnson, W., Turkheimer, E., Gottesman, I. I., & Bouchard, T. J. (2009). Beyond heritability: Twin studies in behavioral research. Current Directions in Psychological Science, 18, 217-220. [I am personally acquainted with three of the four co-authors of this paper, one of whom regularly exchanges links with me by email.]

http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...

"Moreover, even highly heritable traits can be strongly manipulated by the environment, so heritability has little if anything to do with controllability. For example, height is on the order of 90% heritable, yet North and South Koreans, who come from the same genetic background, presently differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."

Turkheimer, E. (2008, Spring). A better way to use twins for developmental research. LIFE Newsletter, 2, 1-5.

http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...

"Unfortunately, that fundamental intuition is wrong. Heritability isn’t an index of how genetic a trait is. A great deal of time has been wasted in the effort of measuring the heritability of traits in the false expectation that somehow the genetic nature of psychological phenomena would be revealed. There are many reasons for making this strong statement, but the most important of them harkens back to the description of heritability as an effect size."

The way to reality-check someone's impression of how the world works is to gather more data. In human intelligence research, James R. Flynn (a co-author of the paper under review here) has enjoyed particular success in making claims that run against the "everyone knows" bias of individual differences psychologists, and then being backed up by other psychologistics (and getting published in the top journals in psychology) when data are found to back him up.

Here is what Arthur Jensen said about Flynn quite a few years ago, and he hasn't retracted this statment: "Now and then I am asked . . . who, in my opinion, are the most respectable critics of my position on the race-IQ issue? The name James R. Flynn is by far the first that comes to mind." Modgil, Sohan & Modgil, Celia (Eds.) (1987) Arthur Jensen: Concensus and Controversy New York: Falmer. Here's what Charles Murray (all right, neither a psychologist nor a geneticist, but, as the review points out, an author who has written about these issues) says in his back cover blurb for Flynn's book What Is Intelligence?: "This book is a gold mine of pointers to interesting work, much of which was new to me. All of us who wrestle with the extraordinarily difficult questions about intelligence that Flynn discusses are in his debt." As N. J. Mackintosh writes about the data Flynn found in his book IQ and Human Intelligence: "the data are surprising, demolish some long-cherished beliefs, and raise a number of other interesting issues along the way." Flynn has earned the respect and praise of any honest researcher who takes time to read the primary source literature. Robert Sternberg, Ian Deary, Stephen Pinker, Stephen Ceci, Sir Michael Rutter, and plenty of other eminent psychologists recommend Flynn's research.