What Is Intelligence?: Beyond the Flynn Effect

Around their 18th birthday, basically all Dutch males born between 1934 and 1964 unknowingly took part in a study of the malleability of intelligence. When these young men appeared before the Dutch military draft board, they took a non-verbal IQ test based on Raven’s (1960) Progressive Matrices. With a little help from Piet Vroon, James Flynn (1987) discovered that those born in 1934 (cohort of 1952) scored on average 20 IQ points lower on the test than those born in 1964 (cohort of 1982). This suggested that in only 30 years, the Dutch male population had shown an increase of more than one standard deviation in average IQ. Flynn (1987) also documented this gain in average IQ in 13 other countries over the course of the 20th century and the effect is now commonly known as the Flynn effect. The Flynn effect raises many questions: How can IQ be substantially heritable, yet show such strong gains that appear to be due to environmental factors? Were Dutch males in 1982 so much smarter than Dutch males in 1952?

[1]  J. Flynn.  Where Have All the Liberals Gone?: Race, Class, and Ideals in America , 2008 .

[2]  J. Komlos,et al.  Height of US‐born non‐Hispanic children and adolescents ages 2–19, born 1942–2002 in the NHANES samples , 2007, American journal of human biology : the official journal of the Human Biology Council.

[3]  R. Lynn.  What is intelligence? Beyond the Flynn Effect, J.R. Flynn. Cambridge University Press (2007) , 2007 .

[4]  J. Flynn,et al.  American IQ Gains From 1932 to 2002: The WISC Subtests and Educational Progress , 2007 .

[5]  A. Offer.  The challenge of affluence : self-control and well-being in the United States and Britain since 1950 , 2007 .

[6]  D. Steinberg.  Determining Nature vs. Nurture , 2006 .

[7]  J. Flynn,et al.  Black Americans Reduce the Racial IQ Gap , 2006, Psychological science.

[8]  H.L.J. van der Maas,et al.  A dynamical model of general intelligence: the positive manifold of intelligence by mutualism. , 2006, Psychological review.

[9]  P. Ross,et al.  The expert mind. , 2006, Scientific American.

[10]  Disentangling Age, Cohort and Time Effects in the Additive Model , 2006 .

[11]  R. Sternberg.  The Rainbow Project: Enhancing the SAT through assessments of analytical, practical, and creative skills , 2006 .

[12]  J. Flynn.  Tethering the elephant: Capital cases, IQ, and the Flynn effect. , 2006 .

[13]  C. Blair.  How similar are fluid cognition and general intelligence? A developmental neuroscience perspective on fluid cognition as an aspect of human cognitive ability. , 2006, The Behavioral and brain sciences.

[14]  T. Salthouse.  Mental Exercise and Mental Aging , 2006, Perspectives on psychological science : a journal of the Association for Psychological Science.

[15]  J. Heckman,et al.  The Effects of Cognitive and Noncognitive Abilities on Labor Market Outcomes and Social Behavior , 2006, Journal of Labor Economics.

[16]  D. Schneider.  Smart as We Can Get , 2006 .

[17]  G. Cohen,et al.  The Mature Mind: The Positive Power of the Aging Brain , 2005 .

[18]  Angela L. Duckworth,et al.  Self-Discipline Outdoes IQ in Predicting Academic Performance of Adolescents , 2005, Psychological science.

[19]  Takashi Matsuyama,et al.  Multiphase Learning for an Interval-Based Hybrid Dynamical System , 2005, IEICE Trans. Fundam. Electron. Commun. Comput. Sci..

[20]  G. Meisenberg,et al.  The flynn effect in the caribbean : Generational change of cognitive test performance in dominica , 2005 .

[21]  M. Crowe,et al.  Complexity of work and risk of Alzheimer's disease: a population-based study of Swedish twins. , 2005, The journals of gerontology. Series B, Psychological sciences and social sciences.

[22]  Steven Johnson,et al.  Everything Bad Is Good for You , 2005 .

[23]  L. Melton.  Use it don't lose it , 2005 .

[24]  Roberto Colom,et al.  The Generational Intelligence Gains Are Caused by Decreasing Variance in the Lower Half of the Distribution: Supporting Evidence for the Nutrition Hypothesis. , 2005 .

[25]  Steven L. Thorne,et al.  Rising mean IQ: Cognitive demand of mathematics education for young children, population exposure to formal schooling, and the neurobiology of the prefrontal cortex , 2005 .

[26]  D. Boomsma,et al.  Are intelligence tests measurement invariant over time? Investigating the nature of the Flynn effect , 2004 .

[27]  J. Sundet,et al.  The end of the Flynn effect?: A study of secular trends in mean intelligence test scores of Norwegian conscripts during half a century , 2004 .

[28]  R. Lynn,et al.  New evidence of dysgenic fertility for intelligence in the United States , 2004 .

[29]  S. Ceci,et al.  The Flynn effect and U.S. policies: the impact of rising IQ scores on American society via mental retardation diagnoses. , 2003, The American psychologist.

[30]  A. Must,et al.  The Secular Rise in IQs: In Estonia, the Flynn Effect Is Not a Jensen Effect. , 2003 .

[31]  T. Nettelbeck.  Mental retardation: Definition, classification, and systems of support , 2003 .

[32]  C. S. Green,et al.  Action video game modifies visual selective attention , 2003, Nature.

[33]  M. Sigman,et al.  IQ on the Rise , 2003, Psychological science.

[34]  M. Shayer,et al.  Realising the cognitive potential of children 5-7 with a mathematics focus , 2003 .

[35]  Jeremy E. C. Genovese.  Cognitive Skills Valued by Educators: Historical Content Analysis of Testing in Ohio , 2002 .

[36]  Marcus Richards,et al.  IQ and the Wealth of Nations , 2004, Heredity.

[37]  Practical Intelligence in Everyday Life , 2001 .

[38]  R. Case,et al.  Integrating concepts and tests of intelligence from the differential and developmental traditions , 2001 .

[39]  Ian J. Deary,et al.  Intelligence: A Very Short Introduction , 2001 .

[40]  J. Heckman,et al.  The Importance of Noncognitive Skills: Lessons from the GED Testing Program , 2001 .

[41]  J. Flynn,et al.  Heritability estimates versus large environmental effects: the IQ paradox resolved. , 2001, Psychological review.

[42]  Frederick T. L. Leong,et al.  Appraising Birth Order in Career Assessment: Linkages to Holland's and Super's Models , 2001 .

[43]  T. Teasdale,et al.  Forty-Year Secular Trends in Cognitive Abilties , 2000 .

[44]  Richard S. J. Frackowiak,et al.  Navigation-related structural change in the hippocampi of taxi drivers. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[45]  Elena L. Grigorenko,et al.  Practical Intelligence in Everyday Life , 2000 .

[46]  J. Flynn.  THE HIDDEN HISTORY OF IQ AND SPECIAL EDUCATION Can the Problems Be Solved , 2000 .

[47]  J. Flynn.  How to Defend Humane Ideals: Substitutes for Objectivity , 2000 .

[48]  Robert W. Howard,et al.  Preliminary Real-World Evidence That Average Human Intelligence Really is Rising , 1999 .

[49]  A. Flieller.  Comparison of the development of formal thought in adolescent cohorts aged 10 to 15 years (1967-1996 and 1972-1993) , 1999 .

[50]  J. Flynn,et al.  ISRAELI MILITARY IQ TESTS: GENDER DIFFERENCES SMALL; IQ GAINS LARGE , 1998, Journal of Biosocial Science.

[51]  J. Flynn.  WAIS–III and WISC–III IQ Gains in the United States from 1972 to 1995: How to Compensate for Obsolete Norms , 1998 .

[52]  R. Martorell.  Nutrition and the worldwide rise in IQ scores. , 1998 .

[53]  C. Schooler.  Environmental complexity and the Flynn effect. , 1998 .

[54]  Ulric Neisser,et al.  The rising curve: Long-term gains in IQ and related measures. , 1998 .

[55]  Patricia M. Greenfield,et al.  The cultural evolution of IQ. , 1998 .

[56]  James R. Flynn,et al.  IQ gains over time: Toward finding the causes. , 1998 .

[57]  R. Catley,et al.  America and Americans in Australia , 1998 .

[58]  I. Deary,et al.  A triarchic theory of Jensenism: Persistent, conservative reductionism , 1998 .

[59]  W. Helsen,et al.  The influence of relative age on success and dropout in male soccer players , 1998, American journal of human biology : the official journal of the Human Biology Council.

[60]  D. Goleman.  Working with Emotional Intelligence , 1998 .

[61]  Ted Nettelbeck,et al.  Jensen's chronometric research: Neither simple nor sufficient but a good place to start , 1998 .

[62]  A. Jensen,et al.  The g factor , 1996, Nature.

[63]  J. Rosenau,et al.  A New Dynamism in World Politics: Increasingly Skillful Individuals? , 1997 .

[64]  I. L. Zimmerman,et al.  Review of the Criterion-Related Validity of the WISC–III: The First Five Years , 1997, Perceptual and motor skills.

[65]  J. P. Rushton,et al.  Cranial size and IQ in Asian Americans from birth to age seven , 1997 .

[66]  Andrew J. Oswald,et al.  Happiness and economic performance , 1997 .

[67]  Richard Lynn,et al.  Dysgenics: Genetic Deterioration in Modern Populations , 1996 .

[68]  Hans J. Eysenck,et al.  Brain, Mind, and Behavior: A New Perspective on Human Nature , 1996 .

[69]  R. Lynn.  Racial and ethnic differences in intelligence in the United States on the Differential Ability Scale , 1996 .

[70]  C. Brand.  Race, evolution, and behavior : a life history perspective , 1995 .

[71]  R. Easterlin.  Will raising the incomes of all increase the happiness of all , 1995 .

[72]  D. Andrich,et al.  Psychometric Evidence of Intellectual Growth Spurts in Early Adolescence , 1994 .

[73]  Patricia A. Whang,et al.  Speed of Accessing Arithmetic Facts in Long-Term Memory: A Comparison of Chinese-American and Anglo-American Children. , 1994 .

[74]  P. Frensch,et al.  Effects of video game playing on measures of spatial performance: Gender effects in late adolescence. , 1994 .

[75]  J. Flynn.  Skodak and skeels: The inflated mother-child IQ gap , 1993 .

[76]  R Kelley,et al.  How Bell Labs creates star performers. , 1993, Harvard business review.

[77]  Sven-Eric Reuterberg,et al.  Changing differences in intelligence? Comparisons between groups of 13-year-olds tested from 1960 to 1990. , 1993 .

[78]  R. Veenhoven,et al.  Happiness in nations: Subjective appreciation of life in 56 nations 1946–1992. , 1993 .

[79]  Rumjahn Hoosain,et al.  Psycholinguistic Implications for Linguistic Relativity: A Case Study of Chinese , 1991 .

[80]  H. Eysenck,et al.  Reaction Times and Intelligence in Chinese and British Children , 1991 .

[81]  J. Flynn.  Reaction Times Show That Both Chinese and British Children are More Intelligent Than One Another , 1991 .

[82]  J. Flynn.  Asian Americans: Achievement Beyond Iq , 1991 .

[83]  Intelligence and giftedness: The contributions of heredity and early environment. , 1990 .

[84]  R. Lynn.  A NUTRITION THEORY OF THE SECULAR INCREASES IN INTELLIGENCE; POSITIVE CORRELATIONS BETWEEN HEIGHT, HEAD SIZE AND IQ , 1989 .

[85]  Thomas W. Teasdale,et al.  Continuing secular increases in intelligence and a stable prevalence of high intelligence levels , 1989 .

[86]  H. Garber.  The Milwaukee Project Preventing Mental Retardation in Children at Risk , 1988 .

[87]  R. Sternberg.  The Triarchic Mind: A New Theory of Human Intelligence , 1988 .

[88]  Japan: Land of the rising IQ: A reply to Flynn. , 1987 .

[89]  J. Flynn.  Massive IQ gains in 14 nations: What IQ tests really measure. , 1987 .

[90]  M. Iona.  What is g , 1987 .

[91]  J. Flynn,et al.  Wechsler Intelligence Tests: do we really have a criterion of mental retardation? , 1985, American journal of mental deficiency.

[92]  J. Flynn.  IQ GAINS AND THE BINET DECREMENTS , 1984 .

[93]  James R. Flynn,et al.  The mean IQ of Americans: Massive gains 1932 to 1978. , 1984 .

[94]  C. Hertzog,et al.  Fourteen-year cohort-sequential analyses of adult intellectual development. , 1983 .

[95]  A. Jensen,et al.  Effects of inbreeding on mental-ability factors , 1983 .

[96]  P. Vernon.  The abilities and achievements of Orientals in North America , 1982 .

[97]  A. Jensen,et al.  Straight Talk About Mental Tests , 1983 .

[98]  A. Jensen,et al.  Bias in Mental Testing , 1980 .

[99]  R. Willis,et al.  The foundations of primitive thought , 1979 .

[100]  A. Jensen,et al.  The Nature of Intelligence and Its Relation to Learning. , 1978 .

[101]  M. Shayer,et al.  THE DISTRIBUTION OF PIAGETIAN STAGES OF THINKING IN BRITISH MIDDLE AND SECONDARY SCHOOL CHILDREN , 1976 .

[102]  M. Cole,et al.  Cognitive Development: Its Cultural and Social Foundations , 1976 .

[103]  J. Folger,et al.  Education of the American Population , 1975 .

[104]  E. Callaway.  Brain electrical potentials and individual psychological differences , 1975 .

[105]  A. Jensen,et al.  Educability and group differences , 1974, Nature.

[106]  R. Easterlin.  Does Economic Growth Improve the Human Lot? Some Empirical Evidence , 1974 .

[107]  A. Jensen,et al.  Genetics and education , 1973 .

[108]  THE PREVENTION OF SUBCULTURAL SUBNORMALITY: PROBLEMS AND PROSPECTS , 1973 .

[109]  L. Hudson.  Frames of Mind: Ability, Perception and Self-Perception in the Arts and Sciences , 1970 .

[110]  R. Lewontin.  2. Further Remarks on Race and the Genetics of Intelligence , 1970 .

[111]  R. Lewontin.  Race and Intelligence , 1970 .

[112]  Moses Rischin.  The creative elite in America , 1967 .

[113]  W. Schull,et al.  The effects of inbreeding on Japanese children , 1965 .

[114]  R. M. Hare,et al.  Freedom and reason , 1964 .

[115]  J. Raven,et al.  Manual for Raven's progressive matrices and vocabulary scales , 1962 .

[116]  P. Mussen.  Child development and personality , 1956 .

[117]  A. D. Ritchie,et al.  Reason in Ethics , 1951, Nature.

[118]  Marie Skodak,et al.  A Final Follow-Up Study of One Hundred Adopted Children , 1949 .

[119]  R. D. Tuddenham.  Soldier intelligence in World Wars I and II. , 1948, The American psychologist.

[120]  E. Thorndike.  Intelligence and its uses. , 1920 .

[121]  C. Spearman.  General intelligence Objectively Determined and Measured , 1904 .

[122]  F. L. Olmsted.  The Cotton Kingdom , 1861 .