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The relationship between nations and IQ is a controversial area of study concerning differences between nations in average intelligence test scores, their possible causes, and their correlation with measures of social well-being and economic prosperity.
This debate started in the early 2000's after Richard Lynn and Tatu Vanhanen constructed and published IQ estimates for many countries using literature reviews, student assessment studies and other methodologies. Their results and conclusions caused significant controversy, and their approach has been criticized on theoretical and methodological grounds.
Subsequent research by psychologists such as Earl B. Hunt, Jelte Wicherts and Heiner Rindermann has focused on identifying potential national differences in IQ, investigating possible causal factors, and determining the nature of the relationship of IQ to variables such as GDP, life expectancy, and governance.
Earl B. Hunt writes that economists traditionally view differences in wealth between nations in terms of human capital, which is a general term for the abilities of the workforce. According to Hunt, international studies of IQ are important because they measure the cognitive skills necessary to excel in a post-industrial world. [1] Richard Lynn and Tatu Vanhanen published the books IQ and the Wealth of Nations and IQ and Global Inequality , which led to further investigations by other researchers, some of them highly critical of Lynn and Vanhanen's methods and conclusions. [2]
The 1981 article "Average IQ values in various European countries" by Vinko Buj is the only international IQ study that over a short time period has compared IQs using the same IQ test. Rindermann (2007) states that it is of dubious quality with scant information regarding how it was done. [3] [4]
In the books IQ and the Wealth of Nations (2002) and IQ and Global Inequality (2006), Richard Lynn and Tatu Vanhanen created estimates of average IQs for 113 nations. They estimated IQs of 79 other nations based on neighboring nations or by other methods. They also created an estimate of "quality of human conditions" for each nation based on gross national product per capita, adult literacy rate, fraction of the population to enroll in secondary education, life expectancy, and rate of democratization. Lynn and Vanhanen found a substantial correlation between the national IQ scores they created and these various socioeconomic factors. They conclude that national IQ influences these measures of well-being, and that national differences in IQ are heavily influenced by genetics, although they also allow for some environmental contributions to it. They regard nutrition as the most important environmental factor, and education a secondary factor. [5]
Many negative reviews of these books have been published in the scholarly literature. In particular, the claim that the IQ tests employed are culturally neutral and unbiased has been criticized, [6] [7] [8] as have the methods used to compile the data. [9] [10] [11] [12]
Susan Barnett and Wendy Williams characterized IQ and the Wealth of Nations as "an edifice built on layer upon layer of arbitrary assumptions and selective data manipulation. The data on which the entire book is based are of questionable validity and are used in ways that cannot be justified." [9]
Rindermann wrote that Lynn and Vanhanen's mixture of many different tests and the not always clear representativeness of the samples seem to be the most serious problems. Furthermore, the measurement years vary, which is problematic because of the Flynn effect. He also argued that the method of averaging neighboring countries for an estimation for the many nations that did not have measured IQs is likely problematic because some research indicates that absence of IQ tests indicates conditions such as poverty or war that may affect IQs, and that "In addition, some errors in the data have been observed". [3]
On July 27, 2020, the European Human Behavior and Evolution Association issued a formal statement opposing the utilization of Lynn's national IQ dataset, citing various methodological concerns. They concluded "Any conclusions drawn from analyses which use these data are therefore unsound, and no reliable evolutionary work should be using these data." [10]
In 2009 Jelte M. Wicherts, Conor V. Dolan, and Han L.J. van der Maas conducted a new analysis of IQ in sub-Saharan Africa, which was critical of many of Lynn and Vanhanen's methods. [12] Wicherts et al. concluded that Lynn and Vanhanen had relied on unsystematic methodology by failing to publish their criteria for including or excluding studies. They found that Lynn and Vanhanen's exclusion of studies had depressed their IQ estimate for sub-Saharan Africa, and that including studies excluded in "IQ and Global Inequality" resulted in average IQ of 82 for sub-Saharan Africa, lower than the average in Western countries, but higher than Lynn and Vanhanen's estimate of 67. Wicherts at al. conclude that this difference is likely due to sub-Saharan Africa having limited access to modern advances in education, nutrition and health care. [11]
Rindermann (2007) states that the correlations between scores of international student assessment studies and psychometric measures of national IQ are very high. His analysis found many of the same groupings and correlations found by Lynn and Vanhanen, with the lowest scores in sub-Saharan Africa, and a correlation of .60 between cognitive skill and GDP per capita. According to Hunt, Rindermann's analysis was more reliable than those by Lynn and Vanhanen. [13] However, a 2017 systematic review notes that other researchers have dismissed Rindermann's findings on the basis that "the meaning of variables shifts when you aggregate to different levels; a conceptual, methodological point that is well-established in the field of multi-level modelling." [14] In particular, James Flynn writes that "Rindermann's results suggest that different factors lie behind the emergence of g in international comparisons and the emergence of g when we compare the differential performance of individuals. This renders g(l) and g(ID) so unlike that they have little significance in common." [15] Similarly, Martin Brunner and Romain Martin argue that Rindermann's identification of "a common factor underlying measures of intelligence and student achievement on the cross-national level" is methodologically flawed, stating that given "the level of analysis applied . . . this factor cannot be interpreted as general cognitive ability (g). Rather it is an indicator of a nation's prosperity." [16]
Hunt argues that substantial correlations between intelligence test scores and measures of well-being also exist when the analysis is limited to developed countries, where the IQ results are more likely to be accurate. [2] Hunt and Wittman (2008) state that although the correlation between national IQ and economic well-being is clear, any possible causality between them is more difficult to determine. [17]
Since the 20th century, there have been worldwide continual increases in measured IQ. This rise has been correlated with degrees of rising education levels, and as such may provide a partial explanation for observed differences in average IQ scores between nations. Wicherts et al. have suggested that national differences in IQ could be because African countries have not yet experienced the improvements that cause the Flynn effect in the developed world, such as improvements in nutrition and health, and educational attainment. [11] Wicherts, Borsboom, and Dolan (2010) criticized evolutionary studies for problems such as ignoring or assuming that the Flynn effect is equal worldwide and assuming that there have been no migrations and changes in climate over the course of evolution. They argue that "national IQs are strongly confounded with the current developmental status of countries. National IQs correlate with all the variables that have been suggested to have caused the Flynn Effect in the developed world." [18]
Eppig, Fincher, and Thornhill (2010) states that the most important factor in predicting national IQ by a large margin is the prevalence of infectious disease. The authors argue that "From an energetics standpoint, a developing human will have difficulty building a brain and fighting off infectious diseases at the same time, as both are very metabolically costly tasks" and that "the Flynn effect may be caused in part by the decrease in the intensity of infectious diseases as nations develop." [19]
David Marks (2010) argues that differences in average IQ scores between national groups and across time periods can be fully accounted for by differences in literacy levels, and that "IQ distributions will converge if opportunities are equalized for different population groups to achieve the same high level of literacy skills." [20]
Several authors, including Leon Kamin in The Science and Politics of IQ , [21] Angela Saini in Superior: The Return of Race Science , [22] and John P. Jackson, Jr. and Nadine M. Weidman in Race, Racism, and Science, [23] have argued that since the early years of IQ testing comparisons between nations have been used to justify discrimination against people based on race, ethnicity, and national origin. In their review of IQ and the Wealth of Nations, Susan Barnett and Wendy Williams write that cross-country comparisons of IQ are "virtually meaningless" due to "an omnipresent ... confusion of correlation with causation that undermines the foundation of the book." [9]
The Flynn effect is the substantial and long-sustained increase in both fluid and crystallized intelligence test scores that were measured in many parts of the world over the 20th century, named after researcher James Flynn (1934–2020). When intelligence quotient (IQ) tests are initially standardized using a sample of test-takers, by convention the average of the test results is set to 100 and their standard deviation is set to 15 or 16 IQ points. When IQ tests are revised, they are again standardized using a new sample of test-takers, usually born more recently than the first; the average result is set to 100. When the new test subjects take the older tests, in almost every case their average scores are significantly above 100.
An intelligence quotient (IQ) is a total score derived from a set of standardised tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern for the German term Intelligenzquotient, his term for a scoring method for intelligence tests at University of Breslau he advocated in a 1912 book.
James Robert Flynn was an American-born New Zealand moral philosopher and intelligence researcher. Originally from Washington, D.C., and educated at the University of Chicago, Flynn emigrated to Dunedin in 1963, where he taught political studies at the University of Otago. He was noted for his publications about the continued year-after-year increase of IQ scores throughout the world, which is now referred to as the Flynn effect. In addition to his academic work, he championed social democratic politics throughout his life.
Discussions of race and intelligence – specifically regarding claims of differences in intelligence along racial lines – have appeared in both popular science and academic research since the modern concept of race was first introduced. With the inception of IQ testing in the early 20th century, differences in average test performance between racial groups were observed, though these differences have fluctuated and in many cases steadily decreased over time. Complicating the issue, modern science has concluded that race is a socially constructed phenomenon rather than a biological reality, and there exist various conflicting definitions of intelligence. In particular, the validity of IQ testing as a metric for human intelligence is disputed. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between groups, and that observed differences are environmental in origin.
The Mismeasure of Man is a 1981 book by paleontologist Stephen Jay Gould. The book is both a history and critique of the statistical methods and cultural motivations underlying biological determinism, the belief that "the social and economic differences between human groups—primarily races, classes, and sexes—arise from inherited, inborn distinctions and that society, in this sense, is an accurate reflection of biology".
Human intelligence is the intellectual capability of humans, which is marked by complex cognitive feats and high levels of motivation and self-awareness. Using their intelligence, humans are able to learn, form concepts, understand, and apply logic and reason. Human intelligence is also thought to encompass our capacities to recognize patterns, plan, innovate, solve problems, make decisions, retain information, and use language to communicate.
The g factor is a construct developed in psychometric investigations of cognitive abilities and human intelligence. It is a variable that summarizes positive correlations among different cognitive tasks, reflecting the fact that an individual's performance on one type of cognitive task tends to be comparable to that person's performance on other kinds of cognitive tasks. The g factor typically accounts for 40 to 50 percent of the between-individual performance differences on a given cognitive test, and composite scores based on many tests are frequently regarded as estimates of individuals' standing on the g factor. The terms IQ, general intelligence, general cognitive ability, general mental ability, and simply intelligence are often used interchangeably to refer to this common core shared by cognitive tests. However, the g factor itself is a mathematical construct indicating the level of observed correlation between cognitive tasks. The measured value of this construct depends on the cognitive tasks that are used, and little is known about the underlying causes of the observed correlations.
IQ and the Wealth of Nations is a 2002 book by psychologist Richard Lynn and political scientist Tatu Vanhanen. The authors argue that differences in national income are correlated with differences in the average national intelligence quotient (IQ). They further argue that differences in average national IQs constitute one important factor, but not the only one, contributing to differences in national wealth and rates of economic growth.
Richard Lynn was a controversial English psychologist and self-described "scientific racist" who advocated for a genetic relationship between race and intelligence. He was a professor emeritus of psychology at Ulster University, but had the title withdrawn by the university in 2018. He was the editor-in-chief of Mankind Quarterly, which is commonly described as a white supremacist journal. Lynn was lecturer in psychology at the University of Exeter and professor of psychology at the Economic and Social Research Institute, Dublin, and at the University of Ulster at Coleraine.
Spearman's hypothesis has two formulations. The original formulation was that the magnitudes of the black-white differences on tests of cognitive ability positively correlate with the tests' g-loading. The subsequent formulation was that the magnitude of the black-white difference on tests of cognitive ability is entirely or mainly a function of the extent to which a test measures general mental ability, or g.
The Minnesota Transracial Adoption Study examined the IQ test scores of 130 black or interracial children adopted by advantaged white families. The aim of the study was to determine the contribution of environmental and genetic factors to the poor performance of black children on IQ tests as compared to white children. The initial study was published in 1976 by Sandra Scarr and Richard A. Weinberg. A follow-up study was published in 1992 by Richard Weinberg, Sandra Scarr and Irwin D. Waldman. Another related study investigating social adjustment in a subsample of the adopted black children was published in 1996. The 1992 follow-up study found that "social environment maintains a dominant role in determining the average IQ level of black and interracial children and that both social and genetic variables contribute to individual variations among them."
Research on the heritability of IQ inquires into the degree of variation in IQ within a population that is due to genetic variation between individuals in that population. There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century. Intelligence in the normal range is a polygenic trait, meaning that it is influenced by more than one gene, and in the case of intelligence at least 500 genes. Further, explaining the similarity in IQ of closely related persons requires careful study because environmental factors may be correlated with genetic factors.
Race Differences in Intelligence: An Evolutionary Analysis is a 2006 book by controversial race and intelligence writer Richard Lynn. The book reviews selected literature on IQ testing and argues that genetic racial differences exist, with a discussion of the causes and consequences. Reviews of the book fault the selection of data used, the methodology, and the conclusions drawn from the data, resulting in criticism that it is "the sort of book that gives IQ testing a bad name."
The study of height and intelligence examines correlations between human height and human intelligence. Some epidemiological research on the subject has shown that there is a small but statistically significant positive correlation between height and intelligence after controlling for socioeconomic class and parental education. The cited study, however, does not draw any conclusions about height and intelligence, but rather suggests "a continuing effect of post-natal growth on childhood cognition beyond the age of 9 years." This correlation arises in both the developed and developing world and persists across age groups. An individual's taller stature has been attributed to higher economic status, which often translates to a higher quality of nutrition. This correlation, however, can be inverted to characterize one's socioeconomic status as a consequence of stature, where shorter stature can attract discrimination that affects many factors, among them employment, and treatment by educators. One such theory argues that since height strongly correlates with white and gray matter volume, it may act as a biomarker for cerebral development which itself mediates intelligence. Competing explanations include that certain genetic factors may influence both height and intelligence, or that both height and intelligence may be affected in similar ways by adverse environmental exposures during development. Measurements of the total surface area and mean thickness of the cortical grey matter using a magnetic resonance imaging (MRI) revealed that the height of individuals had a positive correlation with the total cortical surface area. This supports the idea that genes that influence height also influence total surface area of the brain, which in turn influences intelligence, resulting in the correlation. Other explanations further qualify the positive correlation between height and intelligence, suggesting that because the correlation becomes weaker with higher socioeconomic class and education level, environmental factors could partially override any genetic factors affecting both characteristics.
IQ and Global Inequality is a 2006 book by psychologist Richard Lynn and political scientist Tatu Vanhanen. IQ and Global Inequality is follow-up to their 2002 book IQ and the Wealth of Nations, an expansion of the argument that international differences in current economic development are due in part to differences in average national intelligence as indicated by national IQ estimates, and a response to critics. The book was published by Washington Summit Publishers, a white nationalist and eugenicist publishing group.
What Is Intelligence?: Beyond the Flynn Effect is a book by psychologist James R. Flynn which outlines his model for an explanation of the eponymous Flynn effect. The book summarizes much of the work of Flynn in this area, as well as that of his colleague William Dickens of the Brookings Institution.
The history of the race and intelligence controversy concerns the historical development of a debate about possible explanations of group differences encountered in the study of race and intelligence. Since the beginning of IQ testing around the time of World War I, there have been observed differences between the average scores of different population groups, and there have been debates over whether this is mainly due to environmental and cultural factors, or mainly due to some as yet undiscovered genetic factor, or whether such a dichotomy between environmental and genetic factors is the appropriate framing of the debate. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between racial groups.
The following outline is provided as an overview of and topical guide to human intelligence:
Heiner Rindermann is a German psychologist and educational researcher.
Sex differences in human intelligence have long been a topic of debate among researchers and scholars. It is now recognized that there are no significant sex differences in general intelligence, though particular subtypes of intelligence vary somewhat between sexes.
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