June 26, 2006

Some academic articles on IQ: abstracts from the journal Intelligence

Below are some of the abstracts from the academic journal Intelligence. Although the articles concerned do of course assume a considerable academic background in the subject, I am optimistic that many readers here would be able to get the drift of the articles concerned. If you find the few papers I have grabbed below to be interesting, log on and read the rest.

Exponential correlation of IQ and the wealth of nations: "Plots of mean IQ and per capita real Gross Domestic Product for groups of 81 and 185 nations, as collected by Lynn and Vanhanen, are best fitted by an exponential function of the form: GDP = a * 10b*(IQ), where a and b are empirical constants. Exponential fitting yields markedly higher correlation coefficients than either linear or quadratic. The implication of exponential fitting is that a given increment in IQ, anywhere along the IQ scale, results in a given percentage in GDP, rather than a given dollar increase as linear fitting would predict. As a rough rule of thumb, an increase of 10 points in mean IQ results in a doubling of the per capita GDP."

Testing the cross-racial generality of Spearman's hypothesis in two samples : "Spearman's hypothesis states that racial differences in IQ between Blacks (B) and Whites (W) are due primarily to differences in the g factor. This hypothesis is often confirmed, but it is less certain whether it generalizes to other races. We therefore tested its cross-racial generality by comparing American subjects of European descent (W) to American Hispanics (H) in two different databases. The first [Centers for Disease Control (1988). Health status of Vietnam veterans. Journal of the American Medical Association 259, 2701-2719; Centers for Disease Control (1989). Health status of Vietnam veterans: Vol IV. Psychological and neuropsychological evaluation. Atlanta, Georgia: Center for Environmental Health and Injury Control] contains 4462 middle-aged Armed Services Veterans males, and the second database (NLSY1979) holds 11,625 young male and female adults. Both samples are fairly representative of the general American population. Race differences in general intelligence g were calculated and vectors of test scores were correlated with the vectors of the tests' g loadings, following Jensen [Jensen, A. R. (1998). The g factor. Westport, CT: Praeger]. W scored about 0.8 S.D. above H. The racial difference on the tests correlated significantly with the g-loadings of the tests in the VES database, but less so in the NLSY database. We therefore conclude that the present study supports, but does not unequivocally verify, the cross-racial generality of the Spearman's hypothesis."

g and the measurement of Multiple Intelligences: A response to Gardner : "Specifically, Gardner questioned the construct validity of g, and suggested that the measures we used to test his theory were contaminated with verbal and logical demands. In this reply, we explain that the construct validity of g is well established, pointing out (a) that g is expressed in a wide variety of tasks (not all of which are "school-like" tasks), (b) that g predicts many important criterion variables (not only academic achievement), and (c) that g has a well-established biological basis. With regard to the measures used in our study, we point out that the verbal content of those tasks is unlikely to contribute to individual differences in task performance, and that the logical content of those tasks is consistent with Gardner's description of his intelligence domains.

On the high intelligence and cognitive achievements of Jews in Britain: "A number of studies in the United States have found that Jews obtain higher average IQs than white gentiles. This paper examines whether this is also the case in Britain. Three early studies are summarized that found that Jews in Britain have mean IQs in the range of 110-113. New data are presented for two nationally representative samples of 7-16 year olds in which Jews had mean IQs of 108.5 and 107.7. Taking all five studies into account, it is proposed that the best reading of the IQ of Jews in Britain is 110. It is proposed that the best reading of the IQ of Jews in the United States is 109.5. Data are presented for the numbers of Jewish Fellows of the Royal Society in relation to their proportion in the population. It is found that Jews were over-represented by a factor of 3.7 in the years 1901 through 1940 and by a factor of 7.6 in the years 1950 through 2003. Data are also presented for the numbers Jewish Nobel prize-winners in Britain and the United States for 1901 through 2003. It is shown that Jews are over-represented among Nobel prize-winners by a factor of 8.0 in Britain and 12.3 in the United States. It is proposed that the over-representation of Jews among Nobel prize-winners can be partly explained by the higher average Jewish IQ.

For slightly easier reading, Chris Brand has just done another installment of his news about IQ




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