American Psychologist Intelligence: New Findings and Theoretical Developments Richard E. Nisbett, Joshua Aronson, Clancy Blair, William Dickens, James Flynn, Diane F. Halpern, and Eric Turkheimer Online First Publication, January 2, 2012. doi: 10.1037/a0026699 CITATION 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. Advance online publication. doi: 10.1037/a0026699 Intelligence New Findings and Theoretical Developments Richard E. Nisbett University of Michigan Joshua Aronson and Clancy Blair New York University William Dickens Northeastern University James Flynn University of Otago Diane F. Halpern Claremont McKenna College Eric Turkheimer University of Virginia We review new findings and new theoretical developments on IQ; and that educational and other interventions have in the field of intelligence. New findings include the follow- little impact on IQ and little effect on racial differences in ing: (a) Heritability of IQ varies significantly by social IQ. The authors were skeptical about the ability of public class. (b) Almost no genetic polymorphisms have been policy initiatives to have much impact on IQ or IQ-related discovered that are consistently associated with variation outcomes. in IQ in the normal range. (c) Much has been learned The Bell Curve sold more than 300,000 copies and about the biological underpinnings of intelligence. (d) was given enormous attention by the press, which was “Crystallized” and “fluid” IQ are quite different aspects of largely uncritical of the methods and conclusions of the intelligence at both the behavioral and biological levels. book. The Science Directorate of the American Psycholog- (e) The importance of the environment for IQ is established ical Association felt it was important to present the con- by the 12-point to 18-point increase in IQ when children sensus of intelligence experts on the issues raised by the are adopted from working-class to middle-class homes. (f) book, and to that end a group of experts representing a wide Even when improvements in IQ produced by the most range of views was commissioned to produce a summary of effective early childhood interventions fail to persist, there facts that were widely agreed upon in the field and a survey can be very marked effects on academic achievement and of what the experts felt were important questions requiring life outcomes. (g) In most developed countries studied, further research. The leader of the group was Ulrich Neis- gains on IQ tests have continued, and they are beginning in ser, and the article that was produced was critical of The the developing world. (h) Sex differences in aspects of Bell Curve in some important respects (Neisser et al., intelligence are due partly to identifiable biological factors 1996). The article was also an excellent summary of what and partly to socialization factors. (i) The IQ gap between the great majority of experts believed to be the facts about Blacks and Whites has been reduced by 0.33 SD in recent intelligence at the time and important future directions for years. We report theorizing concerning (a) the relationship research. between working memory and intelligence, (b) the appar- Fifteen years after publication of the review by Neis- ent contradiction between strong heritability effects on IQ ser and colleagues (1996), a great many important new and strong secular effects on IQ, (c) whether a general facts about intelligence have been discovered. It is our intelligence factor could arise from initially largely inde- pendent cognitive skills, (d) the relation between self-reg- ulation and cognitive skills, and (e) the effects of stress on intelligence. Richard E. Nisbett, Institute for Social Research, University of Michigan; Joshua Aronson and Clancy Blair, Department of Applied Psychology, Keywords: intelligence, fluid and crystallized intelligence, New York University; William Dickens, Department of Economics, environmental and genetic influences, heritability, race and Northeastern University; James Flynn, Department of Psychology, Uni- versity of Otago, Dunedin, New Zealand; Diane F. Halpern, Department sex differences of Psychology, Claremont McKenna College; Eric Turkheimer, Depart- ment of Psychology, University of Virginia. n 1994, a controversial book about intelligence by The writing of this article and much of the research that went into it Richard Herrnstein and Charles Murray called The Bell were supported by a generous grant from the Russell Sage Foundation, by Curve was published. The book argued that IQ tests are National Institute on Aging Grant 1 R01 AG029509-01A2, and by Na- I tional Science Foundation Grant 2007: BCS 0717982. The views pre- an accurate measure of intelligence; that IQ is a strong sented here are not necessarily those of the National Science Foundation. predictor of school and career achievement; that IQ is We thank Angela Duckworth, Richard Haier, Susanne Jaeggi, John highly heritable; that IQ is little influenced by environmen- Jonides, Scott Kaufman, John Protzko, Carl Shulman, Robert Sternberg, and Oscar Ybarra for their critiques of an earlier version of this article. tal factors; that racial differences in IQ are likely due at Correspondence concerning this article should be addressed to Rich- least in part, and perhaps in large part, to genetics; that ard E. Nisbett, Institute for Social Research, 3229 East Hall, University of environmental effects of all kinds have only a modest effect Michigan, Ann Arbor, MI 48109. E-mail: [email protected] Month 2012 ● American Psychologist 1 © 2012 American Psychological Association 0003-066X/12/$12.00 Vol. ●●, No. ●, 000–000 DOI: 10.1037/a0026699 intent in this review to update the Neisser et al. article very narrowly defined tasks, those with higher IQs outper- (which remains in many ways a good summary of the field form those with lower IQs on average, with the effects of of intelligence). There are three chief respects in which our IQ being largest for those occupations and tasks that are review differs importantly from that of Neisser and col- most demanding of cognitive skills (F. L. Schmidt & leagues: (a) Due in part to imaging techniques, a great deal Hunter, 1998, 2004). It is important to remain vigilant for is now known about the biology of intelligence. (b) Much misuse of scores on tests of intelligence or any other more is known about the effects of environment on intel- psychological assessment and to look for possible biases in ligence, and a great deal of that knowledge points toward any measure, but intelligence test scores remain useful assigning a larger role to the environment than did Neisser when applied in a thoughtful and transparent manner. and colleagues and toward a more optimistic attitude about IQ is also important because some group differences intervention possibilities. (c) More is now known about the are large and predictive of performance in many domains. effects of genes on intelligence and on the interaction of Much evidence indicates that it would be difficult to over- genes and the environment. Our article also presents a wide come racial disadvantage if IQ differences could not be range of new theoretical questions and reviews some at- ameliorated. IQ tests help us to track the changes in intel- tempted solutions to those questions. We do not claim to ligence of different groups and of entire nations and to represent the full range of views about intelligence. We do measure the impact of interventions intended to improve maintain, however, that few of the findings we report have intelligence. been widely contradicted. Where we are aware of contro- Types of intelligence other than the analytic kind versy, we provide sources where readers can be exposed to examined by IQ tests certainly have a reality. Robert Stern- alternative views. We acknowledge that the theoretical berg and his colleagues (Sternberg, 1999, 2006) have stud- questions we raise might not be the ones that every expert ied practical intelligence, which they define as the ability would agree are the most important ones, and we recognize to solve concrete problems in real life that require search- that not every expert will agree with our views on these ing for information not necessarily contained in a problem questions. We have referenced alternative views where we statement, and for which many solutions are possible, as are aware that such exist. well as creativity, or the ability to come up with novel The article is organized under the rubrics of genes and solutions to problems and to originate interesting questions. the environment, new knowledge about the effects of the Sternberg and his colleagues maintain that both practical environment, new knowledge about interventions, the bi- intelligence and creativity can be measured, that they cor- ology of intelligence, group differences in IQ, and impor- relate only moderately with analytic intelligence as mea- tant unresolved issues. Our working definition of intelli- sured by IQ tests, and that they can predict significant gence is essentially that offered by Linda Gottfredson amounts of variance in academic and occupational achieve- (1997): ment over and above what can be predicted by IQ measures alone. Early claims by Sternberg were disputed by other [Intelligence] . involves the ability to reason, plan, solve prob- intelligence researchers (Brody, 2003; Gottfredson, 2003a, lems, think abstractly, comprehend complex