(5) In discussing Burt's (1940) now discredited and probably fictitious data on the IQs of identical twins reared apart, [note: Burt appears to have been the victim of a politically-motivated slander, and the case agaainst him is now collapsing: see Nature 340:439 (10 Aug. 1989); 352:120 (11 July, 1991); 354:97 (14 Nov. 1991)], Gould writes, "It is scarcely surprising that Arthur Jensen used Sir Cyril's figures as the most important datum in his notorious article (1969) on supposedly inherited and ineradicable differences in intelligence between whites and blacks in America" (p. 235). In fact, I have never used twin differences in any aspect of the discussion of racial differences, except when pointing out the errors in this approach by a number of psychologists who had held that monozygotic twin differences in IQ (because they are entirely nongenetic) favor a strictly environmental interpretation of the observed race differences in IQ (Jensen, 1973, p. 161).
(6) Gould claims that "[h]e [Jensen] believes that all God's creatures can be ordered on a g scale from amoebae at the bottom (p. 175 [Jensen, 1980a]) to extraterrestrial intelligences at the top (p. 248 [ibidem])" (p. 317). This will be recognized by any fair- minded person who has read my Bias in Mental Testing (Jensen, 1980a) as a gross travesty of one section in that book, namely, a section summarizing some of the main research findings on animal intelligence (pp. 175- 182). (Note that I have referred to "extraterrestrial beings" 74 pages later in another context, and not as being at the "top" of anything!) To top it off, Gould then refers to his own travesty as" Jensen's caricature of evolution"! Disbelieving readers may find it instructive to compare Jensen's (1980a) Chapter 6 with Gould's flagrant caricature of its content, with "reified" g as an "object" ascending on a "unilinear" evolutionary hierarchy of all existing species from amoebae to extraterrestrial beings! Such a picture is, of course, utter nonsense, but it is Gould's nonsense, not Jensen's.
(7) Gould writes: "Arthur Jensen (1980a, pp. 361- 362) supports the value of IQ as a measure of innate intelligence by claiming that the correlation between brain size and IQ is about 0.30. He doesn't doubt that the correlation is meaningful and that 'there has been a direct causal effect, through natural selection in the course of human evolution, between intelligence and brain size'" (p. 108). What Gould does not indicate is that this hypothesis was never represented as my own claim. Rather, it was explicitly and accurately represented as a paraphrase of the most up- to- date and technically sophisticated review of the evidence on human brain size and intelligence available, by Leigh Van Valen (1974), a biologist at the University of Chicago. Why then does Gould not cite Van Valen's thorough and scholarly treatment of this topic? Instead he makes it appear that Van Valen's conclusions are simply Jensen's claim. Moreover, the Jensen chapter has merely summarized the literature on the various physical correlates of IQ (including brain size, brain- evoked potentials, stature, basal metabolic rate, obesity, and myopia). Contrary to Gould's paraphrase, it has offered no opinions at all about the meaning of these correlations with respect to the "innateness of IQ."
(8) In a recent publication (Jensen, 1980a, p. 535), I have presented new evidence for Spearman's (1927, p. 379) observation that the magnitudes of the average white- black differences on various tests are positively related to the g factor loadings of the tests, a point in my review that is germane to factor- analytic criteria of test bias. Gould writes, "Jensen also uses g more specifically to buttress his claim that the average difference in IQ between whites and blacks records an innate deficiency of intelligence among blacks" (p. 319). Nowhere in the cited reference (Jensen, 1980a) (or in any other publication) have I ever erred by inferring genetic causation of racial differences from the g factor or any other use off actor analysis, and nowhere have I "claimed" an "innate deficiency" of intelligence in blacks. My position on this question is clearly spelled out in my most recent book: "The plain fact is that at present there exists no scientifically satisfactory explanation for the differences between the IQ distributions in the black and white populations. The only genuine consensus among well- informed scientists on this topic is that the cause of the difference remains an open question" (Jensen, 1981a, p. 213). Apparently Gould does not tolerate so openly agnostic a stance on scientific questions which have important social implications.
Despite Gould's poor batting average for accuracy and fairness in his paraphrasing of references to Jensen, may we hope that he has perhaps afforded more impartial treatment to all the other targets of his critique:
Brain Size and Intelligence
Gould devotes two chapters to race and sex differences in brain size, and to the relationship between brain size and intelligence. Again, though practically all the studies cited are more than 100 years old, Gould meticulously points out their errors and biases.
Brain size is of some scientific interest in relation to intelligence, presumably because the great increase of brain size in the course of human evolution resulted primarily from the selective advantage of the greater capacity for complex learning and problem- solving ability conferred by a larger cerebrum. It seems a natural question whether variation in brain size (or any other features of the brain) is related to differences in psychometric intelligence among contemporary humans. After dismissing the pioneer studies, Gould is wholly uninformative about current thought and evidence on this topic.
Van Valen's (1974) well- known review and analysis of the evidence on brain size and intelligence is conspicuous by its absence from Gould's book. Although Van Valen's article is an excellent review, it unfortunately overlooks one crucial point. That point concerns any correlation between different traits, especially correlations between physical and psychological traits, namely, whether the obtained correlation represents a functional (i. e., causal) relationship between the variables or merely an adventitious genetic correlation resulting from the common assortment of the genes for the two traits as a consequence of cross- assortative mating for the two traits (e.g., if blue- eyed persons mated only with curly- haired persons, blue eyes and curly hair could become correlated in the population, even though there is no intrinsic connection between these characteristics). No study of the correlation between brain size and intelligence, to my knowledge, has applied the necessary methodology based on sibling data (explicated by Jensen, 1980b) to rule out mere assortative genetic correlation between these variables. Until this is done, the theoretical significance of the correlation (whatever its magnitude may be) between brain size and IQ remains unknown. Any correlation existing between families but not within families (i.e., not among siblings), is scientifically empty as far as advancing our understanding of the nature of intelligence. Evidence suggests that such is the case for the population correlation (of about 0.25) between height and IQ. This does not mean, however, that one must automatically partial height out of the brain- size x IQ correlation, as Gould advocates. Theoretical interpretation of the intercorrelations among brain size, body size, and IQ is possible only by means of genetical analysis (e.g., analysis employing data on between and within- family correlations) combined with path analysis.
The essence of Gould's message in his two chapters on race and sex differences in brain size, and the relationship between brain size and intelligence is that craniometry served no valid scientific purpose, but was merely an expression of the prejudicial self- interest of comfortable white males. But to complain that an investigator's conjectures stem from personal prejudices (or any other source) is, of course, scientifically irrelevant. The importance of scientific conjecture arises solely from its relation to some theory and its testability, or susceptibility to empirical refutation. Gould's disparagement of craniometry, however, seems to serve merely as a prelude to the more currently important topic of intelligence testing. Gould writes: "Craniometric arguments lost much of their luster in our century, as determinists switched their allegiance to intelligence testing- amore "direct" path to the same invalid goal of ranking groups by mental worth- and as scientists exposed the prejudiced nonsense that dominated most literature on form and size of the head" (p. 108). Not surprisingly, in the last two- thirds of his book, Gould launches a concerted attack on the "prejudiced nonsense" of intelligence testing.
IQ Heritability
Gould's first broadside against intelligence testing is an 88- page chapter entitled "The Hereditarian Theory of IQ. "The most remarkable feature of this chapter is that it does not present even a hint of the kinds of evidence, or the quantitative- genetic methods applied thereto, which have caused many reasonable and fair- minded contemporary scientists to conclude that genetic factors are substantially involved in individual differences in IQ. The reader is told nothing at all about the polygenetic basis of individual differences or about the logic of quantitative genetics and its application to the various kinship correlations on which the "Hereditarian Theory of IQ" is based. Naive readers will be completely misled as to the true nature of the current popular controversy over the inheritance of mental ability.
Instead, they will read about the first (1905) Binet tests and about how Binet's early American followers, Goddard and Terman, allegedly corrupted Binet's intentions by reifying the IQ as an inborn "thing" in order that it might better serve as an instrument of social and racial discrimination. About 30 percent of the chapter is taken up with a fine- grained critique of the psychometrically primitive 1917 army tests and the purported influence of the test results on U.S. immigration policy in the 1920s, which, we are told, was promoted by" Teutonic supremacists."
The Cox (1926), and Terman estimates of the IQs of eminent historical figures, based on biographical accounts of their childhood accomplishments, are also unfairly ridiculed by Gould in this chapter. For example, Gould points out that such major acknowledged geniuses as Copernicus and Faraday were assigned lower IQs than some figures of lesser eminence (e.g., Galton, with an estimated childhood IQ of 200). But Cox's monograph makes it very clear that the estimated IQs are the minimum values that could be estimated on the basis of the available evidence of early- life accomplishments. (Shakespeare, for example, was completely omitted because of inadequate biographical evidence.) In fact, no attempt was made in the monograph itself to rank- order individual historic geniuses by their estimated IQs. The aim of the Terman and Cox study was simply to see if there might be evidence for a higher average level of mental precocity among the world's famous geniuses- and there clearly is. All the inherent methodological limitations of the study are fully acknowledged in Cox's (1926) thoroughly careful monograph. Gould supplies no new information by his sarcastic embellishment.
By this point in Gould's book, the weight of vituperative excess will no doubt have caused even technically naive but intelligent readers to begin to question whether the most influential figures in the early history of mental testing could really have been so utterly foolish and wicked as Gould makes them appear. The fact that Galton, Goddard, Yerkes, Terman, Brigham, Thorndike, and other pioneers of psychometrics may have expressed poorly founded and occasionally dogmatic hereditarian opinions concerning intelligence at a time before any adequately developed methodology or suitable evidence was available for the genetical analysis of mental test data, cannot legitimately be construed as an indictment of all subsequent research in this area. Yet Gould never mentions any of the considerable body of recent work in behavioral genetics. One wonders, does he avoid it perhaps because the technical issues cannot be so simplistically and entertainingly lampooned as the early efforts of the pioneer mental testers?
The "hereditarian fallacy" (p. 156) is described by Gould as (1) the implication that" heritable" is equated with "inevitable," and
(2) the assumption that if genetic factors explain a certain proportion of the individual differences variance within population groups, they explain the same proportion of the mean differences between various populations, such as racial groups. This" hereditarian fallacy" constitutes a strawperson if ever there was one. I cannot recall a single living "hereditarian" who has ever expressed either of these beliefs, though I know of many who have noted their inherent logical fallacy. I myself, dubbed by Gould as "America's best- known hereditarian," have attempted in several publications from 1969 to 1982 to explicate the illogic of trying to prove the heritability of mean differences between groups from a knowledge of the heritability of individual differences within groups. I have also attempted over the years to dispel the common, but unwarranted, assumption that heritability necessarily implies the inevitability or immutability of human differences. (A nontechnical treatment of these matters is found in Jensen [1981a, pp. 108- 115 and 226- 232].) Certainly these issues are more complex than Gould's brief treatment even begins to suggest; they require considerably more explication than he presents, for even the barest understanding of them. Correctly understood, moreover, these are not matters of theoretical contention among behavioral geneticists.
The "Reification " of General Intelligence
In a chapter entitled "The Real Error of Cyril Burt," we come to the core of Gould's argument: his perceived necessity for demolishing the concept of g, Spearman's symbol for the common factor in all cognitive tests. Because g constitutes by far the largest part of the variance in all "intelligence" tests, it is often termed the "general intelligence" factor. Gould gives a good nonmathematical explanation of the workings of factor analysis (and principal components analysis) and how g and other factors are "extracted" from a correlation matrix. After this quite acceptable explanation, Gould begins his battle.
According to Gould, g is the quintessential abomination. He writes, "The chimerical nature of g is the rotten core of Jensen's edifice, and of the entire hereditarian school" (p. 320). What especially makes g so awful, according to Gould, is the error of reification. This, he claims, is the "real error" of Cyril Burt, and also of Charles Spearman, the inventor of factor analysis and the discoverer of g. These pioneers in the field are charged with the crime reifying g. Yet the kind of outlandish verbal reification for which they stand accused is, in fact, absolutely contrary to any expression about g that one can find in the works of Spearman or Burt, or, indeed, in any of the serious literature of factor analysis and intelligence, The g factor as supposedly conceived by Spearman and Burt is variously referred to by Gould as "ineluctable, innate general intelligence," "innate essence of intelligence," a "hard, quantifiable thing," a "quantifiable fundamental particle," a "single, scalable, fundamental 'thing' residing in the human brain," "a 'thing' in the most direct, material sense," and so forth. This language is all completely misleading. More importantly, it is Gould's language, and not the language of those he chooses to discuss.
Reified or not, the factor g itself and factor analysis in general have nothing to do with "innateness" or the nature- nurture question. Whether individual differences (or group differences) in g factor scores have a heritable component or not is an entirely separate question, which cannot be answered by any methods of factor analysis, but only by the methods of quantitative genetic analysis.
Moreover, to anyone who has carefully- read the major works of Burt and Spearman on factor analysis, the claim that they (or any other experts in this field) are guilty of reifying g will be recognized as another straw person, an unqualified hoax. Few psychologists, or few scientists in any field for that matter, have been as sophisticated in the philosophy of science as Spearman and Burt. The most sophisticated discussion of the whole issue of the meaning of factors to be found in the entire literature is Burt's( 1940) chapter entitled "The Metaphysical Status of Mental Factors." In it, Burt states" [t]o speak of factors of the mind as if they existed in the same way as, but in addition to, the physical organs and tissues of the body and their properties, is assuredly indefensible and misleading" (p. 218). Burt's entire discussion is well worth reading even today. Surely no one before or since has ever presented a more intellectually profound and subtle consideration of the nature and interpretation of the factors derived by the factor analysis of mental tests.
As will be equally apparent to anyone reading Spearman's (1927) great work, The Abilities of Man, he too was fully aware of the reification issue. Certainly Spearman makes it extremely clear that he intended his hypothesis of g as "mental energy" as just that- a hypothesis, a theoretical attempt to account for the phenomenon which the g factor highlights and quantifies, namely, positive manifold (i.e., the presence of all positive intercorrelations among all diverse tests of cognitive abilities, when the tests are given to representative samples of the general population). Spearman made no apologies for hypothesizing causal mechanisms to explain y. Quite the contrary:
(Psychology] is a science in its own right, and can no more fulfill this mission without hypotheses than a man can run properly with his legs tied in a sack. What would physics do without its electrons, its ether, or its heat, none of which are, or perhaps even can be, directly perceived? Indeed, there is no necessity for believing that such entities really exist at all. (p. 128)
In fact, what Gould has mistaken for "reification" is neither more nor less than the common practice in every science of hypothesizing explanatory models or theories to account for the observed relationships within a given domain. Well- known examples include the heliocentric theory of planetary motion, the Bohr atom, the electromagnetic field, the kinetic theory of gases, gravitation, quarks, Mendelian genes, mass, velocity, and so forth. None of these constructs exists as a palpable entity occupying physical space. The g factor, and theories attempting to explain g in terms of models independent of factor analysis itself, are essentially no different from the other constructs of science listed above. Nor is there any good reason that hypothetical models attempting to account for g should necessarily exclude all considerations of neural or biochemical processes. All such theoretical speculations about the nature of g, whether offered by Spearman, Burt, Jensen, or anyone else, have involved hypothetical processes or system concepts, presumably going on in the brain (where else?). But these theories have never depicted g as some "single," "ineluctable," "hard," "object," of the sort characterized by Gould. Would Gould then deny psychology the common right of every science to the use of hypothetical constructs or any theoretical speculation concerning causal explanations of its observable phenomena? He writes," My complaint lies with the practice of assuming that the mere existence of a factor, in itself, provides a license for causal speculation" (p.268). But haven't all sciences always exercised free license for theoretical speculation about the causes of the observable phenomena in their domains? Of course they have.
The crucial question, which is summarized by the existence of the g factor is this: In respect to what processes or mechanisms is it that persons who perform well on anyone test, in general, also perform well on many other tests, even on tests that are highly dissimilar in content and sensory and motor modalities? The concept of intelligence depends not on the fact that people can be ranked by this test or that, but rather on the fact that, whatever the test, so long as it is cognitive in the broadest sense, a positive correlation emerges between the ranks for any two tests. If an IQ test were just a rag- bag collection of cognitive tasks that did not all measure a common factor, there could be no positive manifold. Scientists today are trying to understand the causes of positive manifold, and this is what the present g theory is all about. Gould offers no alternative ideas to account for all these well- established observations. His mission in this area appears entirely nihilistic.
L. L. Thurstone, the leading American psychometrician and factor analyst, might have emerged as a minor hero in Gould's drama, were it not for his alleged tendencies toward factor reification and his avowed hereditarian stance. At least Thurstone's factors were a number of "primary mental abilities" and not the unholy g. Gould dubs Thurstone "the exterminating angel of Spearman's g" (p. 296). With the development of multiple- factor analysis, Thurstone had chosen to rotate the factor axes in such a way as to maximize the variance of the loadings on all the latent common factors in a correlation matrix (a criterion he termed "simple structure"), a procedure that yields a number of first- order factors, or "primary mental abilities" (e.g., verbal, numerical, spatial, memory). According to Gould, "the hegemony of g was broken. >From the midst of an economic depression that reduced many of its intellectual elite to poverty, an America with egalitarian ideals (however rarely practiced) challenged Britain's traditional equation of social class with innate worth. Spearman's g had been rotated away, and general mental worth evaporated with it" (p. 304). Actually, the g variance was not at all "exterminated" by Thurstone's method, but merely' dispersed among the primary factors. Later, Thurstone himself realized that he could obtain a closer fit to his criterion of simple structure by allowing the factor axes to be obliquely rotated (i.e., correlated). Thurstone also came to realize that subsequent factor analysis of the intercorrelations among the oblique primary factors would recover the g factor, essentially the same g as arrived at by the Spearman and Burt methods of g extraction!
In discussing Thurstone's primary abilities, Gould states, "Some children are good at some things, others excel in different and independent qualities of mind" (p. 304). If Gould is talking about cognitive abilities, this statement is deceptively plausible (because we know that everyone is better at certain things than at others). In the context of his discussion of factor analysis, however, it is essentially wrong and misleading. If Gould's statement were wholly true, a second- order g factor could not emerge from any large collection of diverse mental tests. Yet, in fact, a second- order g always appears for all cognitive tests obtained in any representative sample of the general population. (This is equivalent to saying that the overall ability differences between individuals are generally greater than the average differences that exist between various abilities within individuals). Moreover, g factor scores, when g is extracted either as a first principal factor (Spearman- Burt) or as a hierarchical, second- order factor (Thurstone), are generally very highly correlated with one another, usually above .95 in most factor analyses of the same battery of tests in the same subject sample. (Congruence coefficients between the g factor loadings in the two methods are usually even higher.) True, the hierarchical, second- order g carries somewhat less variance than the g extracted as a first principal factor, but Gould greatly exaggerates this point in his effort to belittle the second- order g, In 10 factor analyses of Wechsler subtest batteries that I have examined, in which g has been extracted both as a first principal component and as a hierarchical second- order factor (using the Schmid- Leiman, 1957, transformation), the second- order g accounts for about 8O percent of the variance accounted for by the first principal component. The second- order g also accounts for about two- thirds of the total common- factor variance in the test battery, whereas the three primary factors (verbal, performance, and memory), after g is removed, account for about one- third of the variance. It would be a rare, even freakish, collection of cognitive tests that would yield a g which, by any proper method of extraction, would be subordinate to any of the rotated first- order factors.
No knowledgeable factor analyst of either the Spearmanian or Thurstonian school disputes the fact that the various methods or models of factor analysis are all mathematically equivalent in their ability to" account for" the matrix of intercorrelations. Other, nonmathematical considerations must determine preferences for one method over another. Although the number of factors that can be extracted from a correlation matrix is necessarily limited by the number of variables, there is virtually an infinite number of possible rotations of the factor axes, and hence an infinity of different possible factors. There is no rule in science that restricts the particular factors that any investigator may choose to focus upon. Some factor solutions make much more sense, psychologically, than others, however, and psychologists may suspect that there is more "pay dirt" in certain factors than there is in others.
In this respect, factor solutions that yield a g, and the g factor itself, have generally been of greatest interest throughout the history of psychometry. More scientific curiosity has been stirred up by g than by any other products of factor analysis, and for a number of good reasons. Here is a baker's dozen:
(1) The fundamental reason is the phenomenon of positive manifold: that is, the existence of positive correlations between all tests in the cognitive domain, over a wide range of diversity, regardless of the content or other surface characteristics of the tests. The g factor represents this salient fact of nature better than any other single factor or any combination of multiple orthogonal factors (which disperse the g variance and thus artificially create the misleading impression that there are zero correlations among the several clusters of tests defining group factors or primary abilities).
(2) Taken together, the g factor plus smaller group factors (primary abilities independent of g) best represent the fact that, on average, overall differences between individuals in the population are greater than the differences among various abilities within individuals. Multiple orthogonal factors, without g, would not lead us to this (empirically established) expectation.
(3) Certain tests (generally those involving greater complexity of mental manipulation) are consistently more g- loaded than others, when analyzed in different batteries of various tests. Other tests (usually involving sensory- motor skills or rote- learning ability) have rather consistently weak g loadings under these conditions.
(4) Essentially the same g emerges from collections of tests which are superficially quite different. Unlike all other factors, g is not tied to any particular type of item content or acquired cognitive skill. (This is the basis for Spearman's principal of "the indifference of the indicator" of g.)
(5) It has proved impossible to construct a test to measure any of Thurstone's Primary Mental Abilities (or any other first- order cognitive factors) that does not also measure g. That is to say, scores on "factor pure" tests (i.e., tests designed to measure some factor other than g) always measure g in addition to whatever primary ability factor they were specially devised to measure. The g variance in tests of primary mental abilities is, moreover, generally greater than the variance attributable to the primaries. It has proved possible, however, to devise tests that measure g and little or nothing else.
(6) The g factor reflects more of the variance in informal, common- sense estimates of differences in people's intelligence by parents, teachers, employers, and peers than any other factor that can be extracted from psychometric tests. In addition, g discriminates more accurately than any other factor between average persons and persons diagnosed as mentally retarded by independent, nontest criteria, and between average persons and those who are recognized as intellectually gifted on the basis of their accomplishments.
(7) There is no general factor of human learning ability that is different from, or independent of, the g of psychometric tests. However, there is much more "specificity" (i.e., variance not related to any common factors) in learning tasks than in most psychometric tests composed of numerous items.
(8) Although g may not be equally valued in all cultures, individual differences in g- related abilities are easily recognized, even by persons in societies that differ tremendously from Western or industrial civilizations.
(9) In its practical ability to forecast the success of individuals in school and college, in armed forces training programs, in employment in business and industry, and so forth, g carries far more predictive weight than measures of any other factor or any other combination of factors independent of g (see Jensen, 1981 b). This fact also means that many "real life" kinds of performance, and not just psychometric tests, are substantially g- loaded.
(10) Humphreys (1981) has pointed out that even where mental tests are not implicated, the naturally occurring educational and occupational selection in our society involves g more than any other measurable psychological variables. Each "sieve" in the educational and occupational ladders selects on g, and this is as true in those communist countries in which mental ability tests are officially forbidden as it is in the United States. For this and for many other reasons, Humpreys [sic] aptly refers to g as "The primary mental ability."
(11) Although more evidence is still needed for a firm conclusion, what evidence we have suggests that g has the highest degree of heritability of any component of variance in psychometric tests (e.g., Humphreys, 1981 ). The group factors (and specificity) show little or no heritability apart from the heritability of g.
(12) The genetic phenomenon of inbreeding depression (i.e., the diminution of a metric character in the offspring of genetically related parents, such as siblings or cousins) is indicative of genetic dominance of the genes enhancing the trait in question. Large- scale data on the offspring of cousin matings show that the degree of inbreeding depression observed on 11 diverse subtests of the Wechsler Intelligence Scale for children is positively and significantly correlated with the subtests' g loadings (Jensen, in press). (This is equally true whether g is extracted as a first principal factor or as a hierarchical second- order factor.)
( 13) The g factor (and g factor scores) are substantially correlated with measures of the speed of information processing in simple laboratory tasks, such as simple and choice reaction times, which bear no resemblance to the usual psychometric tests from with the g factor is extracted (Jensen, 1980c). Recently it has been found, in a sample of 100 university students, that speed of information processing, as measured by reaction- time techniques, is highly correlated with the g factor of the Wechsler Adult Intelligence Scale, and that no additional component of variance in the 12 WAIS subtests (including the verbal, performance, and memory- factors) shows a significant correlation with the reaction time measures (Vernon, 1981). Vernon writes, "Given the strength of the association between mental speed and g, it is further argued that these attributes are largely the same: a person's intelligence can be defined in terms of the speed and efficiency with which he can execute a number of basic cognitive operations" (p. 83). At an even more basic level, there is now considerable evidence that g is correlated with the amplitude, latency, and complexity of average devoked potentials in the brain, as measured by means of EEG apparatus and electrodes attached to the scalp (e.g., Eysenck, 1981; Jensen, Schafer, & Crinella, 1981). If such important findings are examples of what Gould wishes to suppress by his railing at the "reification" of g, then I will shout three cheers for "reification"!
But Gould does not tell his readers about any of these interesting things on the present scene. The fact is that psychologists have been witnessing in recent years a great revival of interest and research on Spearman's g, research aimed mainly at discovering the basic processes- cognitive and neurophysiological- that will eventually explain the nature of g. That the theory of general intelligence is presently thriving is evidenced in many current publications, such as the relatively new journal Intelligence and the recent multiauthored books edited by Friedman, Das, and O'Conner (1981) Sternberg (1982), and Eysenck (1982). These publications are recommended for readers who want factual, up- to- date information about research on intelligence and mental testing.
Gould's book, on the other hand, is so repetitiously cluttered by doctrinaire disparagement that it can hardly provide any real enlightenment regarding mental measurement. Although Gould's book will be warmly embraced (along with Leon Kamin's, 1974, The Science and Politics of IQ) by the dwindling band of genetic egalitarians and neo- Lysenkoists, it is hard to see that this book makes any scientific contribution or serves to inform the general public in any responsible way about the truly important issues in mental testing today.
Editor's Note. Dr. Gould has been invited to respond to this article for publication in a subsequent issue of CER.
[ The next few issues contain no reply from Gould. If he ever replied, I have been unable to find it. - RS ]
REFERENCES
BURT, C. The factors of the mind: An introduction to factor analysis in psychology. New York: Macmillan, 1940.
COX, C. M. Genetic studies of genious, vol 2: The early mental traits of 300 geniuses. Stanford, Calif.: Stanford University Press, 1926.
EYSENCK, H. J. The nature of intelligence. In M. P. Friedman, J. P. Das, & Neil O'Connor (Eds.), Intelligence and learning. New York: Plenum, 1981.
EYSENCK, H. J. (ED.). A model of intelligence. New York: Springer, 1982.
FRIEDMAN, M. P., DAS, J. P., & O'CONNOR, N. (Eds.). Intelligence and learning. New York: Plenum, 1981.
GOULD, S. J., & ELDREDGE, N. Punctuated equilibrium: The tempo and mode of evolution reconsidered. Paleobiology, 1977, 3, 115- 151.
HUMPHREYS, L. G. The primary mental ability. In M. P. Friedman, J. P. Das, & N. O'Connor (eds.), Intellegence and learning. New York: Plenum, 1981.
JENSEN, A. R. Can we and should we study race differences? In J. Hellmuth (Ed.), Disadvantaged Child, Vol. 3: Compensatory education: A national debate. New York: Brunner/Mazel, 1970.
JENSEN, A. R. Educability and group differences. New York: Harper & Row, 1973.
JENSEN, A. R. Bias in mental testing. New York: The Free Press, 1980. (a)
JENSEN, A. R. Uses of sibling data in psychological and educational research. American Educational Research Journal, 1980), 17, 153- 170. (b)
JENSEN, A. R. Chronometric analysis of intelligence. Journal of Social and Biological Structures, 1980, 3, 103- 122. (c)
JENSEN, A. R. Straight talk about mental tests. New York: Free Press, 1981. (a)
JENSEN, A. R. Test validity: g versus the specificity doctrine. Invited address at the annual convention of The American Psychological Association, Los Angeles, California. August 26, 1981. (b)
JENSEN, A. R. The effects of in breeding on mental ability factors. Personality and Individual Differences, in press.
JENSEN, A. R., SCHAFER, E. W. P., & CRINELLA, F. M. Reaction time, evoked brain potentials, and psychometric g in the severely retarded. Intelligence, 1981, 5, 179- 197.
KAMIN, L. J. The science and politics of IQ. Potomac, Md.: Lawrence Erlbaum, 1974.
SCHMID, J., & LEIMAN, J. M. The development of hierarchical factor solutions. Psychometrika, 1957, 22 53- 61.
SPEARMAN, C. The abilities of man. New York: Macmillan, 1927.
STERNBERG, R. J. (Ed.). Recent advances in research on intelligence. Hillsdale, N.J.: Erlbaum, 1982.
VAN VALEN, L. Brain size and intelligence in man. American Journal of Physical Anthropology, 1974, 40, 417- 423.
VERNON, P. A. Speed of information processing and general intelligence. Unpublished doctoral dissertation, University of California, Berkeley, 1981.
