Ability rise in NAEP and narrowing ethnic gaps?

Measurement-Invariant Fluid Anti-Flynn Effects in Population-Representative German Student Samples (2012-2022)

Generational IQ test scores in the general population were observed to increase over time (i.e., the Flynn effect) across most of the 1900s. However, according to more recent reports, Flynn effect patterns have seemingly become less consistent. So far, most available evidence on this phenomenon has been categorized by drawing on the classic fluid vs. crystallized intelligence taxonomy. However, recent evidence suggests that subdomain-specific trajectories of IQ change may well be more complex. Here, we present evidence for cross-temporal changes in measurement-invariant figural reasoning tasks in three large-scale, population-representative samples of German secondary school students (total N = 19,474). Analyses revealed a consistent pattern of significant and meaningful declines in performance from 2012 to 2022. Results indicate a decrease in figural reasoning of 4.68 to 5.17 IQ points per decade (corresponding to small-to-medium effects, Cohen ds from 0.34 to 0.38). These findings may be interpreted as tentative evidence for a decreasing strength of the positive manifold of intelligence as a potential cause of the increasing number of recent reports about inconsistent IQ change trajectories.

Social Adversity Reduces Polygenic Score Expressivity for General Cognitive Ability, but Not Height

It has been hypothesized that even 'perfect' polygenic scores (PGSs) composed of only causal variants may not be fully portable between different social groups owing to gene-by-environment interactions modifying the expression of relevant variants. The impacts of such interactions involving two forms of social adversity (low socioeconomic status [SES] and discrimination) are examined in relation to the expressivity of a PGS for educational attainment composed of putatively causal variants in a large, representatively sampled and genotyped cohort of US children. A relatively small-magnitude Scarr-Rowe effect is present (SES × PGSEDU predicting General Cognitive Ability [GCA]; sR = .02, 95% CI [.00, .04]), as is a distinct discrimination × PGSEDU interaction predicting GCA (sR = -.02, 95% CI [-.05, 00]). Both are independent of the confounding main effects of 10 ancestral principal components, PGSEDU, SES, discrimination and interactions among these factors. No sex differences were found. These interactions were examined in relation to phenotypic and genotypic data on height, a prospectively more socially neutral trait. They were absent in both cases. The discrimination × PGSEDU interaction is a co-moderator of the differences posited in modern versions of Spearman's hypothesis (along with shared environmentality), lending support to certain environmental explanations of those differences. Behavior-genetic analysis of self-reported discrimination indicates that it is nonsignificantly heritable (h2 = .027, 95% CI [-.05, .10]), meaning that it is not merely proxying some underlying source of heritable phenotypic variability. This suggests that experiences of discrimination might stem instead from the action of purely social forces.

A Half Century of Progress in US Student Achievement: Agency and Flynn Effects, Ethnic and SES Differences

Policymakers, conceptualized here as principals, disagree as to whether US student performance has changed over the past half century. To inform conversations, agents administered seven million psychometrically linked tests in math (m) and reading (rd) in 160 survey waves to national probability samples of cohorts born between 1954 and 2007. Estimated change in standard deviations (sd) per decade varies by agent (m: –0.10sd to 0.27sd, rd: –0.02sd to 0.12sd). Consistent with Flynn effects, median trends show larger gains in m (0.19sd) than in rd (0.04sd), though rates of progress for cohorts born since 1990 have increased in rd but slowed in m. Greater progress is shown by students tested at younger ages (m: 0.31sd, rd: 0.08sd) than when tested in middle years of schooling (m: 0.17sd, rd: 0.03sd) or toward the end of schooling (m: 0.06sd, rd: 0.02sd). Young white students progress more slowly (m: 0.28sd, rd: 0.09sd) than Asian (m: 46sd, rd: 0.28sd), black (m: 0.36sd, rd: 0.19sd), and Hispanic (m: 0.29sd, rd: 0.13sd) students. These ethnic differences generally attenuate as students age. Young students in the bottom quartile of the SES distribution show greater progress than those in the top quartile (difference in m: 0.08sd, in rd: 0.15sd), but the reverse is true for older students. Moderators likely include not only changes in families and schools but also improvements in nutrition, health care, and protection from contagious diseases and environmental risks. International data suggest that subject and age differentials may be due to moderators more general than just the United States.

Updated IQ and Well-Being Scores for the 50 U.S. States

At the level of the 50 U.S. states, an interconnected nexus of well-being variables exists. These variables strongly correlate with estimates of state IQ in interesting ways. However, the state IQ estimates are now more than 16 years old, and the state well-being estimates are over 12 years old. Updated state IQ and well-being estimates are therefore needed. Thus, I first created new state IQ estimates by analyzing scores from both the Program for the International Assessment of Adult Competency (for adults), and the National Assessment of Educational Progress (for fourth and eighth grade children) exams. I also created new global well-being scores by analyzing state variables from the following four well-being subdomains: crime, income, health, and education. When validating the nexus, several interesting correlations existed among the variables. For example, state IQ most strongly predicted FICO credit scores, alcohol consumption (directly), income inequality, and state temperature. Interestingly, state IQ derived here also correlated 0.58 with state IQ estimates from over 100 years ago. Global well-being likewise correlated with many old and new variables in the nexus, including a correlation of 0.80 with IQ. In sum, at the level of the U.S. state, a nexus of important, strongly correlated variables exists. These variables comprise well-being, and state IQ is a central node in this network.

The secular trend of intelligence test scores: The Danish experience for young men born between 1940 and 2000

The present study investigated the Danish secular trend of intelligence test scores among young men born between 1940 and 2000, as well as the possible associations of birth cohort changes in family size, nutrition, education, and intelligence test score variability with the increasing secular trend. The study population included all men born from 1940 to 2000 who appeared before a draft board before 2020 (N = 1,556,770). At the mandatory draft board examination, the approximately 19-year-old men underwent a medical examination and an intelligence test. In the statistical analyses, the IQ mean and standard deviation (SD) were estimated separately for each of the included annual birth cohorts based on information from birth cohorts with available total intelligence test scores for all tested individuals (i.e. 1940-1958 and 1987-2000; the mean and SD were interpolated for the intermediate birth cohorts). Moreover, the possible associations with birth cohort changes in family size, height as a proxy for nutritional status, education, and IQ variability were investigated among those birth cohorts for whom a secular increase in intelligence test scores was found. The results showed that the estimated mean IQ score increased from a baseline set to 100 (SD: 15) among individuals born in 1940 to 108.9 (SD: 12.2) among individuals born in 1980, since when it has decreased. Focusing on the birth cohorts of 1940-1980, for whom a secular increase in intelligence test scores was found, birth cohort changes in family size, height, and education explained large proportions of the birth cohort variance in mean intelligence test scores, suggesting that these factors may be important contributors to the observed Flynn effect in Denmark.

Intelligence and the Individuals with Disabilities Education Act

One of the stated purposes of this Special Issue is to “discuss when and why intelligence has disappeared” in education. In this paper, I argue that intelligence is still heavily involved in public education in the United States due to the Individuals with Disabilities Education Act. Moreover, due to several factors, including high-profile court cases, intelligence tests are legally used in an inconsistent manner in special education decision-making throughout the U.S. These cases illustrate the complex issues surrounding the psychometric properties of intelligence tests, historical conflicts surrounding racial equity, differences in federal versus state policies, and methodological concerns surrounding special education policies are discussed.

Nonlinear Effects of Cognitive Ability on Economic Productivity

Abstract. Cognitive capitalism theory argues that the positive effects of cognitive ability on economic productivity should increase nonlinearly, with increases in ability amplifying increases in productivity. The theory was tested using country-level indicators of cognitive ability and productivity. Cognitive ability was based on international student assessments (e.g., Program for International Student Assessment, PISA), and productivity was based on economic inputs (e.g., scientific achievements and competitiveness) and outputs (e.g., gross domestic product). As predicted, the effects of cognitive ability on all productivity measures increased nonlinearly at higher levels of ability, suggesting that higher ability levels disproportionately boost a nation’s productivity. The findings are discussed in light of standard theories of cognitive ability (e.g., Spearman’s law of diminishing returns and differentiation theories), and suggest that interventions that boost cognitive ability can have large, amplifying effects on economic productivity.

UV Radiation Is Associated With Latitudinal Trends in Cognitive Ability of White Children in the USA

Abstract. Temperature, geo-residential pattern of subpopulations, prevalence of infectious diseases, and UV radiation have been proposed to explain the declining cognitive ability observed with proximity to the equator in the USA. This study tested the cognitive effects of the four variables. The results reveal that the latitudinal decline of cognitive ability is strongly correlated with the UV Index rather than with the other variables among White children. The decline in measured cognitive ability from north to south is absent among African American and Hispanic children, plausibly because the high levels of skin melanin among these ethnic groups, by absorbing and dissipating light, prevent the occurrence of radiation’s cognitive effects among these populations at USA latitudes. The possible physiological mediators (oxidative stress, folate degradation, sexual hormones) suggest diet, family planning, and educational methods as mitigating strategies; however, specific studies measuring the mediating variables are needed to confirm their role and further strengthen UV radiation as an explanatory concept.

One Century of Global IQ Gains: A Formal Meta-Analysis of the Flynn Effect (1909-2013)

The Flynn effect (rising intelligence test performance in the general population over time and generations) varies enigmatically across countries and intelligence domains; its substantive meaning and causes remain elusive. This first formal meta-analysis on the topic revealed worldwide IQ gains across more than one century (1909-2013), based on 271 independent samples, totaling almost 4 million participants, from 31 countries. Key findings include that IQ gains vary according to domain (estimated 0.41, 0.30, 0.28, and 0.21 IQ points annually for fluid, spatial, full-scale, and crystallized IQ test performance, respectively), are stronger for adults than children, and have decreased in more recent decades. Altogether, these findings narrow down proposed theories and candidate factors presumably accounting for the Flynn effect. Factors associated with life history speed seem mainly responsible for the Flynn effect's general trajectory, whereas favorable social multiplier effects and effects related to economic prosperity appear to be responsible for observed differences of the Flynn effect across intelligence domains.

SPEARMAN'S HYPOTHESIS TESTED COMPARING SAUDI ARABIAN CHILDREN AND ADOLESCENTS WITH VARIOUS OTHER GROUPS OF CHILDREN AND ADOLESCENTS ON THE ITEMS OF THE STANDARD PROGRESSIVE MATRICES

Spearman's hypothesis tested at the level of items states that differences between ethnic groups on the items of an IQ test are a function of the g loadings of these items, such that there are small differences between ethnic groups on items with low g loadings and large differences between ethnic groups on items with high g loadings; this has been confirmed in a limited number of studies. In this paper, Spearman's hypothesis was tested, comparing a group of Saudi children and adolescents (N=3209) with other groups of children and adolescents from Denmark, Cyprus, Croatia, Bosnia, South Africa, Estonia, Ukraine, Ireland, Russia and Chile (total N=9333). The analyses were carried out on twelve comparisons between the Saudi Arabian children and the other children. Spearman's hypothesis was confirmed less strongly than in other large-scale studies with a mean weighted r value of 0.44. The relevance of these findings for the discussion on the causes of group differences is discussed.

Cognitive Capitalism: Economic Freedom Moderates the Effects of Intellectual and Average Classes on Economic Productivity

Cognitive ability stimulates economic productivity. However, the effects of cognitive ability may be stronger in free and open economies, where competition rewards merit and achievement. To test this hypothesis, ability levels of intellectual classes (top 5%) and average classes (country averages) were estimated using international student assessments (Programme for International Student Assessment; Trends in International Mathematics and Science Study; and Progress in International Reading Literacy Study) (N = 99 countries). The ability levels were correlated with indicators of economic freedom (Fraser Institute), scientific achievement (patent rates), innovation (Global Innovation Index), competitiveness (Global Competitiveness Index), and wealth (gross domestic product). Ability levels of intellectual and average classes strongly predicted all economic criteria. In addition, economic freedom moderated the effects of cognitive ability (for both classes), with stronger effects at higher levels of freedom. Effects were particularly robust for scientific achievements when the full range of freedom was analyzed. The results support cognitive capitalism theory: cognitive ability stimulates economic productivity, and its effects are enhanced by economic freedom.

Future Cognitive Ability: US IQ Prediction until 2060 Based on NAEP

The US National Assessment of Educational Progress (NAEP) measures cognitive competences in reading and mathematics of US students (last 2012 survey N = 50,000). The long-term development based on results from 1971 to 2012 allows a prediction of future cognitive trends. For predicting US averages also demographic trends have to be considered. The largest groups' (White) average of 1978/80 was set at M = 100 and SD = 15 and was used as a benchmark. Based on two past NAEP development periods for 17-year-old students, 1978/80 to 2012 (more optimistic) and 1992 to 2012 (more pessimistic), and demographic projections from the US Census Bureau, cognitive trends until 2060 for the entire age cohort and ethnic groups were estimated. Estimated population averages for 2060 are 103 (optimistic) or 102 (pessimistic). The average rise per decade is dec = 0.76 or 0.45 IQ points. White-Black and White-Hispanic gaps are declining by half, Asian-White gaps treble. The catch-up of minorities (their faster ability growth) contributes around 2 IQ to the general rise of 3 IQ; however, their larger demographic increase reduces the general rise at about the similar amount (-1.4 IQ). Because minorities with faster ability growth also rise in their population proportion the interactive term is positive (around 1 IQ). Consequences for economic and societal development are discussed.

THE COGNITIVE COMPETENCES OF IMMIGRANT AND NATIVE STUDENTS ACROSS THE WORLD: AN ANALYSIS OF GAPS, POSSIBLE CAUSES AND IMPACT

Immigration, immigration policies and education of immigrants alter competence levels. This study analysed their effects using PISA, TIMSS and PIRLS data (1995 to 2012, N=93 nations) for natives' and immigrants' competences, competence gaps and their population proportions. The mean gap is equivalent to 4.71 IQ points. There are large differences across countries in these gaps ranging from around +12 to -10 IQ points. Migrants' proportions grow roughly 4% per decade. The largest immigrant-based 'brain gains' are observed for Arabian oil-based economies, and the largest 'brain losses' for Central Europe. Regarding causes of native-immigrant gaps, language problems do not seem to explain them. However, English-speaking countries show an advantage. Acculturation within one generation and intermarriage usually reduce native-immigrant gaps (≅1 IQ point). National educational quality reduces gaps, especially school enrolment at a young age, the use of tests and school autonomy. A one standard deviation increase in school quality represents a closing of around 1 IQ point in the native-immigrant gap. A new Greenwich IQ estimation based on UK natives' cognitive ability mean is recommended. An analysis of the first adult OECD study PIAAC revealed that larger proportions of immigrants among adults reduce average competence levels and positive Flynn effects. The effects on economic development and suggestions for immigration and educational policy are discussed.

COGNITIVE ABILITY OF PRESCHOOL, PRIMARY AND SECONDARY SCHOOL CHILDREN IN COSTA RICA

Cognitive abilities of children in Costa Rica and Austria were compared using three age groups (N=385/366). Cognitive ability tests (mental speed, culture reduced/fluid intelligence, literacy/crystallized intelligence) were applied that differed in the extent to which they refer to school-related knowledge. Preschool children (kindergarten, 5–6 years old,NCR=80,NAu=51) were assessed with the Coloured Progressive Matrices (CPM), primary school children (4th grade, 9–11 years old,NCR=71,NAu=71) with ZVT (a trail-making test), Standard Progressive Matrices (SPM) and items from PIRLS-Reading and TIMSS-Mathematics, and secondary school students (15–16 years old,NCR=48,NAu=48) with ZVT, Advanced Progressive Matrices (APM) and items from PISA-Reading and PISA-Mathematics. Additionally, parents and pupils were given questionnaires covering family characteristics and instruction. Average cognitive abilities were higher in Austria (Greenwich-IQMCR=87 andMAu=99,dIQ=12 points) and differences were smaller in preschool than in secondary school (dIQ=7 vs 20 points). Differences in crystallized intelligence were larger than in fluid intelligence (mental speed:dIQ=12, Raven:dIQ=10, student achievement tests:dIQ=17 IQ points). Differences were larger in comparisons at the level ofg-factors. Austrian children were also taller (6.80 cm,d=1.07 SD), but had lower body mass index (BMICR=19.35 vs BMIAu=17.59,d=−0.89 SD). Different causal hypotheses explaining these differences are compared.