A state level investigation of the associations among intellectual capital, religiosity and reproductive health

The current study examines the degree to which state intellectual capital, state religiosity and reproductive health form a meaningful nexus of ecological relations. Though the specific magnitude of effects vary across outcomes, results from hierarchical regression analyses were consistent with the hypothesized path model indicating that a state's intellectual capital (as indicated by average state IQ and graduation rates at various levels) has a positive overall effect on state reproductive health statistics, whereas state religiosity generally has a negative impact. Specifically, both IQ and education were positively associated with breastfeeding rates, immunization rates, and rates of mammography screening, and negatively associated with teen fertility rates and infant mortality rates. Additionally, results confirm that education rates partially mediate the influence of IQ onto religiosity, and both education and religiosity partially or fully mediate the relation between IQ and state health (depending on specific outcome measure). The current results are consistent with a growing interdisciplinary literature establishing that individual, state and national well-being is substantially related to general mental ability and its covariates.     

III. WISC-R scatter indices: Useful information for differential diagnosis?

This study analyzed the WISC-R verbal-performance, full scale IQ, verbal IQ, and performance IQ scatter indices of 101 verified special education students. The results indicated that none of these measures discriminated among emotionally disturbed, learning disabled, minimally brain injured, and educable mentally retarded children. These scatter indices were also compared with analogous data collected from a nationwide, representative sample of normal children (Kaufman, 1976a, 1976b). Statistically significant differences were obtained between the two groups on verbal-performance, full scale IQ, and performance IQ scatter dimensions. Further analyses revealed, however, that 40% of the normal children exhibited as much or more scatter than the average special education student on each of these three scatter indices. There were no significant differences between the two groups on the verbal IQ scatter index. The results are discussed in terms of the limited utility of WISC-R scatter indices for the purpose of differential diagnosis.     

State IQ and suicide rates in the United States

Previous findings pertaining to the direction (positive or negative) of the ecological correlation between intelligence and suicide rates in the USA have been conflicting. Using novel state IQ estimates, derived from the Scholastic Assessment Test, the American College Test, these tests combined, or the National Assessment of Educational Progress state scores, these estimates were not consistently associated to state suicide rates. Whereas ACT-derived state IQ was significantly positively correlated with suicide rates, the correlation with composite ACT-SAT-derived state IQ was significantly negative and with both SAT-derived and NAEP-derived state IQ also negative but not significant. Validity checks pointed to possible methodological problems with the state IQ estimates. Currently available estimates of state IQ, therefore, seem not appropriate to resolve the question of the direction of the ecological correlation of intelligence and suicide mortality across the USA.     

Effects of IQ on Executive Function Measures in Children with ADHD

The present study compared children with Attention-Deficit Hyperactivity Disorder (ADHD) and controls on a selected set of clinical measures of executive function (EF). A total of 92 children (51 ADHD, 41 control), ages 6-16, completed measures chosen from a larger neuropsychological battery to illustrate diverse components of the EF construct (planning, inhibitory control, response preparation, memory search). The selected measures were moderately correlated with one another, and moderately correlated with IQ. After controlling for age, sex, presence of learning disability (LD), ADHD, and IQ test version, Full Scale IQ was significantly related to four of the five selected EF measures. A second analysis showed group differences on the EF measures at different IQ levels. After covarying for age, there was a significant multivariate effect for IQ level (average, high average, superior) and a significant multivariate interaction between group (ADHD vs. control) and IQ level. Three of the five selected EF measures showed significant univariate group effects (controls performing better than ADHD) at the average IQ level; however, there were no significant group differences between children with ADHD and controls at high average or superior IQ levels. These results suggest that clinical measures of EF may differ among children with ADHD and controls at average IQ levels, but there is poorer discriminatory power for these measures among children with above average IQ.     

Effects of IQ on executive function measures in children with ADHD.

The present study compared children with Attention-Deficit Hyperactivity Disorder (ADHD) and controls on a selected set of clinical measures of executive function (EF). A total of 92 children (51 ADHD, 41 control), ages 6-16, completed measures chosen from a larger neuropsychological battery to illustrate diverse components of the EF construct (planning, inhibitory control, response preparation, memory search). The selected measures were moderately correlated with one another, and moderately correlated with IQ. After controlling for age, sex, presence of learning disability (LD), ADHD, and IQ test version, Full Scale IQ was significantly related to four of the five selected EF measures. A second analysis showed group differences on the EF measures at different IQ levels. After covarying for age, there was a significant multivariate effect for IQ level (average, high average, superior) and a significant multivariate interaction between group (ADHD vs. control) and IQ level. Three of the five selected EF measures showed significant univariate group effects (controls performing better than ADHD) at the average IQ level; however, there were no significant group differences between children with ADHD and controls at high average or superior IQ levels. These results suggest that clinical measures of EF may differ among children with ADHD and controls at average IQ levels, but there is poorer discriminatory power for these measures among children with above average IQ.     

Estimating state IQ: Measurement challenges and preliminary correlates

The purpose of this study is threefold. First, an estimate of state IQ is derived and its strengths and limitations are considered. To that end, an indicator of downward bias in estimating state IQ is provided. Two preliminary causal models are offered that predict state IQ. These models were found to be highly predictive of state IQ, yielding multiple R's of 0.83 and 0.89. Second, the extent to which state IQ predicts state outcome variables (e.g., gross state product, health, violent crime, and government effectiveness) is estimated. State IQ shows positive correlations with gross state product, health, and government effectiveness and negative correlations with violent crime. These results are consistent with the extent to which IQ predicts outcomes at the level of the individual. Third, a research agenda is provided for improving estimates of state IQ, identifying factors that cause differences in state IQ, and delineating the role of IQ in predicting important variables.     

Parasite prevalence and the distribution of intelligence among the states of the USA

In this study, we tested the parasite-stress hypothesis for the distribution of intelligence among the USA states: the hypothesis proposes that intelligence emerges from a developmental trade-off between maximizing brain vs. immune function. From this we predicted that among the USA states where infectious disease stress was high, average intelligence would be low and where infectious disease stress was low, average intelligence would be high. As predicted, we found that the correlation between average state IQ and infectious disease stress was ? 0.67 (p < 0.0001) across the 50 states. Furthermore, when controlling the effects of wealth and educational variation among states, infectious disease stress was the best predictor of average state IQ.     

Academic success in adolescence: Relationships among verbal IQ,social support and emotional intelligence

The objective of this study was to examine, by gender, whether emotional intelligence (EI), peer social support, and/or family social support partially mediated the influence of verbal IQ on Grade 10 grade point average (GPA) for 192 students (96 male, 96 female). For male students, EI and peer social support predicted GPA and EI mediated the association between verbal IQ and GPA. For female students, EI, peer social support, and family support predicted GPA but did not mediate the association between verbal IQ and GPA. This study further examined whether subscales of EI (intrapersonal, interpersonal, adaptability, and stress management abilities), peer social support and family social support (emotional, socialising, practical, financial, and advice) added to the prediction of GPA after verbal IQ, gender, and socioeconomic status were controlled. Adaptability, stress management and practical family social support each added to the explanation of variability. None of the peer social support subscales predicted additional variance in GPA.     

State preferences for the ACT versus SAT complicates inferences about SAT-derived state IQ estimates: A comment on Kanazawa (2006)

Kanazawa [Kanazawa, S. (2006). IQ and the wealth of states. Intelligence, 34, 593–600.] offered estimates of state IQ derived from SAT data. The purpose of this commentary is to argue that state preferences for the use of the ACT versus the SAT create biased estimates of SAT-derived state IQ for states where the ACT is more frequently used than the SAT. This error can be reduced by using both ACT and SAT data to estimate state IQ. An IQ estimate based on a ACT-SAT composite and a NAEP-derived state IQ estimate were compared as predictors of three wealth variables. Both IQ estimates cause one to conclude that states with higher mean IQ have larger gross state product per capita, higher median incomes, and a lower percentage of their population in poverty.     

Reaction time and intelligence: A replicated study

Two samples of adult subjects of reasonably average intelligence were given IQ tests and a series of RT tests using 0, 1, 2, and 3 bits of information in a Hick paradigm. Both series showed negative correlation between IQ on the one hand, and RT and σRT, on the other, confirming earlier work. On the other hand, there was no evidence of correlation between the Hick slope and IQ, and the correlation between IQ and RT of σRT did not increase from 1 to 3 bits of information. It was found that the Hick paradigm did not apply to some 20% of the samples, and that the exclusion of these nonconformists increased the correlation between IQ and RT/σRT.     

The relationship between IQ, social class and EEG findings in healthy children investigated by child-psychiatric methods

Abstract.— 222 children aged between 4.5 and 16.5 years. who were found to be normal by strict somato-neuro-logical criteria, were investigated by EEG and by child-psychiatric methods. Intelligence tests were performed according to WISC. The mean intelligence quotient amounted to 116.3± 12.4 in boys and 116.6± 14.1 in girls. Child-psychiatric findings deviating from the strictly normal occurred in 30 children significantly more frequently in social class III compared to I and 11. There was no relationship of significance between IQ and social group. No relevant relationship was found between IQ and psychiatric variables, nor between IQ and EEG-findings. The absence of the normal fixed relationship between IQ and social group is a notable finding, as is also the high average IQ. The strict normal criteria may have contributed to the exclusion of individuals with lesions and thus diminished factors having an inhibitory effect of the development of intelligence.     

IQ correlations in transracial adoptive families

IQ tests were administered to all available members over 4 years old in 101 transracial adoptive families when the adopted children were an average of 7 years old and again when they averaged 17 years old. At both times, 426 members of 93 families were studied; 398 were seen in person and administered the WAIS-R or WISC-R. IQ correlations were calculated for adopted and biological parent-child pairs, and for genetically related and unrelated siblings. Educational levels of birth parents were correlated with the IQ scores of their adopted-away children. Results show that biologically related family members tended to resemble each other intellectually more than did adoptive family members at both time points. IQ correlations for biological parent-child pairs exceeded those for adoptive parent-child pairs, and correlations were greater for genetically related than unrelated siblings. In late adolescence, the IQ scores of unrelated siblings in the transracial adoptive families were more similar than those of unrelated adolescent siblings pairs reported in other studies. The pattern of IQ correlations for unrelated siblings suggested that familial environmental influences on IQ decline from childhood to late adolescence, but this conclusion was not supported by parent-child IQ correlations. The effects of selective placement on familial IQ correlations were small. Estimates of genetic and familial environmental influences on IQ were very similar to those of other studies. This suggests that the influences on intellectual development in this sample of black/interracial adoptees reared in white families are similar to those for children in the majority populations of the United States and Western Europe.     

Role-taking skills in intellectually-gifted third-grade children

Very bright (mean IQ = 152) third graders were compared with both average IQ third graders and average IQ sixth graders on perceptual, cognitive, and affective perspective-taking tasks. The role-taking skills of the intellectually-gifted children were more similar to those of their mental age mates than to those of their chronological age mates on both the cognitive and affective tasks. On the perceptual task, the bright children's performance fell between that of the two comparison groups. The results provide evidence that gifted children are advanced in thinking about both the social and physical worlds, and have implications for educational issues such as curriculum development and acceleration vs. enrichment.     

Relation of Creativity to Fluid and Crystallized Intelligence

The threshold hypothesis regarding creativity and intelligence suggests that these two constructs are positively correlated except at the higher end of the IQ distribution, where they are unrelated. Much of the support for this hypothesis comes from comparisons of correlations within average and high‐IQ groups. However, a common methodological flaw in these comparisons is that the high IQ group is smaller in variance than the average IQ group. In the present study we equated variances for a better test of the threshold hypothesis. College students in two IQ groups completed tests of creativity and intelligence. IQ and creativity correlated at least as strongly in the high IQ group as in the average IQ group, generally failing to support the threshold hypothesis. However, breakdown of composite IQ into fluid and crystallized IQ indicated minimal support for the threshold hypothesis with crystallized IQ, but support for an inverse threshold effect with fluid IQ. Fluid IQ correlated significantly with creativity in the high IQ group but not in the average IQ group, and this pattern was corroborated by regression analyses. Possible explanations for the pattern of results are offered.     

IQ and the wealth of nations: How much reverse causality?

This paper uses data from 130 IQ test administrations worldwide and employs regression analysis to try to quantify the impact of living conditions on average IQ scores in nationally-representative samples. The study emphasizes the possible role of conditions at or near the test-takers' time of birth. The paper finds that the impact of living conditions is of much smaller magnitude than is suggested by just looking at correlations between average IQ scores and socioeconomic indicators. After controlling for test-takers' region of ancestry, the impact of parasitic diseases on average IQ is found to be statistically insignificant when test results from the Caribbean are included in the analysis. As far as IQ and the wealth of nations are concerned, causality thus appears to run mostly from the former to the latter. The test-takers' region of ancestry dominates the regression results. While differences in average scores worldwide can thus be plausibly viewed as being influenced by genetic differences across world regions, it is also possible that score differences are influenced by regional differences in culture that are independent of genetic factors. Differences in average IQ across world regions may change in the years ahead insofar as the strength of Flynn effects may not be uniform, but some regional differences in average g levels seem likely to continue indefinitely.     

弱智儿童视觉图形辨认的实验研究

本研究探讨了不同智商水平的弱智儿童的视觉图形辨认能力的差异,并与同龄正常儿童作了比较。结果表明,智商在31-51,平均智商为41.6,均龄为11.7岁的弱智儿童,在图形以0.05秒速度的呈现条件下,平均辨认正确率为21.4%;在以0.01秒速度呈现的条件下,平均正确率为20.7%。智商在55-75,平均智商为62.0,均龄为10.2岁的弱智儿童,图形以0.05秒速度呈现时,平均辨认正确率为48.5%;在以0.01秒速度呈现时,平均正确率为45.0%。与同均龄的正常儿童比较,无论在哪一种呈现速度条件下,对图形辨认正确率均明显低于正常儿童。     

Mitochondrial DNA marker EST00083 is not associated with high vs. average IQ in a German sample

In a recent report in this journal (Plomin & Petrill, 1997), a mitochondrial DNA marker (EST00083) yielded significant associations with high vs. low IQ in two population-based samples of children in the U.S. The present study tested this allelic association for German adults with high vs. average IQ scores. The high IQ adults (N=47) were members of Mensa, an organization whose membership criterion is an IQ score above 130. Their EST00083 allelic frequencies were compared to the allelic frequencies for a control group of adults (N=77) whose IQ scores were less than 110 as estimated from short-term memory and speed-of information-processing tests. Although the differences between the two studies are considerable, the present results do not provide support for the hypothesis that EST00083 is associated with high IQ.     

Black–White differences on IQ and grades: The mediating role of elementary cognitive tasks

The relationship between IQ scores and elementary cognitive task (ECT) performance is well established, with variance on each largely reflecting the general factor of intelligence, or g. Also ubiquitous are Black–White mean differences on IQ and measures of academic success, like grade point average (GPA). Given C. Spearman's (Spearman, C. (1927). The Abilities of Man. New York: Macmillan) hypothesis that group differences vary directly with a test's g loading, we explored whether ECT performance could mediate Black–White IQ and GPA differences. Undergraduates (139 White and 40 Black) completed the Wonderlic Personnel Test, followed by inspection time and choice reaction time ECTs. Despite restriction of range, ECT performance completely mediated Black–White differences on IQ (d = .45). Group differences on GPA (d = .73), however, were larger and ECT performance did not mediate them. We discuss findings in light of Spearman's hypothesis.     

Assessment of preschoolers at-risk with the WPPSI--R and the Stanford-Binet L-M.

The purpose of this study was to provide data on the validity of using the WPPSI--R with 16 preschoolers who had been referred for psychological assessment. A comparison of the preschoolers' performance on the WPPSI--R and the Stanford-Binet L-M was made. Children ranged in age from 3-0 to 6-0 years, with a mean age of 4-5 yr. The correlations between WPPSI--R and Stanford-Binet L-M scores were strong; WPPSI--R Verbal IQ and Stanford-Binet L-M IQ, r = .85; WPPSI--R Performance IQ and Stanford-Binet L-M IQ, r = .75, and WPPSI--R Full Scale IQ and Stanford-Binet L-M IQ, r = .82. For this very small sample of children whose mean IQ was significantly below average, the WPPSI--R appeared to assess validly their current intellectual functioning. Attention should be given concurrent and predictive validity as well as the efficiency of using the WPPSI--R with other and larger samples of referred children.     

Null sex differences in general intelligence: evidence from the WAIS-III

There is an increasing number of studies claiming that the sex differences in general intelligence are "real." The empirical evidence is based on the summation of the standardized sex differences in several cognitive batteries. However, the scientific construct of general ability rests on the correlations among test scores, rather than on their summation. The latter (ability in general) is an arbitrary variable, not a scientific construct. General ability is not a function of any particular cognitive test, but a source of variance evidenced by the correlation between several diverse tests, each of which reflects general ability (g) to some extent, but also group factors and test specificity. Because there are important educational, economic, and social consequences of a group difference in general ability, it is especially germane to evaluate the possibility of an average sex difference in its proxy measures, such as IQ. The Spanish standardization of the WAIS-III is analyzed in the present study. The sample was made up of 703 females and 666 males, aged 15-94, drawn as a representative sample of the population in terms of educational level and geographical location. Although a male advantage of 3.6 IQ points is observed, the difference is in "ability in general," not in "general ability" (g). Given that the main ingredient of the strong association between IQ and a broad range of social correlates is g, and given that there is no sex difference in g, then the average IQ sex-difference favoring males must be attributed to specific group factors and test specificity.