Differences In General Intelligence Research Articles

General intelligence, personality traits, and motivation as predictors of performance, potential, and rate of advancement of Royal Navy senior officers

ABSTRACT This paper assesses the impact of general intelligence, as well as specific personality traits, and aspects of motivation, on performance, potential, and advancement of senior leaders. A questionnaire survey was conducted on the full population of 381 senior officers in the Royal Navy with an 80% response rate. Performance, potential, and rate of advancement were established direct from the organization’s appraisal system; intelligence, personality traits and motivation were assessed, at the time of the study, using the Verify G+ Test, Occupational Personality Questionnaire, and Motivation Questionnaire. Findings suggest differences in motivation are more important than differences in general intelligence, or personality traits, in predicting assessed performance, potential within, and actual rate of advancement to, senior leadership positions. This is a rare example of a study into very senior leaders, validated against both formal appraisal data and actual rates of advancement. As a consequence of this study the Royal Navy has started to use psychometric-based assessments as part of the selection and development of its most Senior Officers.

Multidimensional Rasch Analysis of Gender Differences in Tes Intelegensi Kolektif Indonesia–Tinggi (TIKI-T)

The empirical evidence on gender differences in the g-factor or general intelligence and various cognitive abilities remains contradictory. Some studies have found that there are no gender differences in general intelligence, while others have found differences between genders in verbal, spatial, and numerical abilities as measured by standardized cognitive tests. This study aims to examine the presence of differential item functioning (DIF) on standardized tests that measure verbal, numerical, and spatial/nonverbal abilities, as well as gender differences in item level. The multidimensional Rasch model was used to identify DIF based on four cognitive domains in the Tes Intelegensi Kolektif IndonesiaTinggi (TIKI-T) test. A total of 1,443 undergraduate students were tested. The results of the study showed that while there were several unbiased items, some items were clearly biased against males or females. The DIF was higher in the numerical and verbal subtests for female-male differences, while the DIF on male tests corresponded to spatial/nonverbal subtest performance. The theoretical and practical implications of the results are discussed.

A Genetic Hypothesis for American Race/Ethnic Differences in Mean [i]g[/i]: A Reply to Warne (2021) with Fifteen New Empirical Tests Using the ABCD Dataset

Intelligence tests are excellent predictors of school and job performance, and racial/ethnic differences in mean IQ are common. Based on five lines of evidence, Warne (2021) builds a case for partly genetic causes of differences in general intelligence (g) across American self/parental-identified race or ethnicity (SIRE). Based on a careful reading of Warne (2021) and the authors he cites, we generated 15 predictions flowing from a partial genetic hypothesis. These predictions concern (1) mean cognitive differences and Spearman’s hypothesis, (2) measurement invariance across European genetic ancestry, (3) high within-group heritability and low shared environmentality, (4) admixture regression for g, (5) polygenic scores, (6) brain volume, and (7) results based on the method of correlated vectors. We used the Adolescent Brain Cognitive Development Study sample (N = 10,245) to test these hypotheses using classical and state-of-the-art statistical techniques. Decomposition of variance using twins showed that the heritability of intelligence and of brain/intracranial volume estimates were, respectively, moderate and high for both the White and the non-White subsamples, while the variance attributable to shared environment was low. Within SIRE groups, both genetic ancestry and education-related polygenic scores (eduPGS) predicted both brain volume and g. Moreover, brain volume was weakly but statistically significantly related to g (r = .14 to .25). Path and mediation analysis showed that total brain volume explained approximately 15% of the association between European ancestry and g and also explained approximately 8% of that between eduPGS and g. Finally, based on the method of correlated vectors (MCV), a positive manifold was found for genetic, brain volume, and ancestry/SIRE-related variables. We conclude that the results support the hypotheses tested and are in line with a partial genetic hypothesis. Keywords: Brain volume, g, Ancestry, Admixture, Heritability, Polygenic scores, SIRE

The sexes do not differ in general intelligence, but they do in some specifics

Reliable and meaningful sex differences exist in specific cognitive abilities despite no reliable or meaningful sex difference in general intelligence. Here we use Cattell-Horn-Carroll (CHC) theory to highlight research findings related to sex differences in intelligence, with a focus on studies of test scores from comprehensive intelligence measures that were obtained from large and representative samples of children and adolescents. Female advantages in latent processing speed and male advantages in latent visual processing are the most meaningful and consistently reported sex differences regarding CHC broad cognitive abilities. Differences have been reported in narrow and specific ability constructs such as mental rotation and object memory location. In academic achievement, the largest and most consistent findings are female advantages in writing, whereas male advantages at higher math ability levels are also found. Empirical descriptions of sex differences should consider the breadth of the construct under study and incorporate analysis beyond simple mean differences. Score analysis methods that utilize multiple-group confirmatory factor models and multiple-indicator multiple cause models are useful to address the former, and analysis methods such as quantile regression and male-female ratio calculations along score distributions are useful to address the latter. An understanding of why specific ability differences exist in combination and in the presence of similarities will improve researchers' understanding of human cognition and educational achievements.

The possible role of field independence/dependence on developmental sex differences in general intelligence

Real-life outcomes for men and women suggest the existence of cognitive sex differences, but the evidence for a sex difference in general intelligence is equivocal. Here, we examine the role of spatial ability for IQ test performance, in light of the developmental hypothesis that male performance increases more than female across adolescence. Using longitudinal data from Block and Block data set on the Wechsler scales and the rod-and-frame test (RFT) for ages 4 (N = 108), 11 (N = 101), and 18 years (N = 100), we find that males' performance becomes greater than females' with age, both on IQ and the RFT. At 18 years of age, males' mean IQ and RFT score was 116.4 and 4.05 (lower scores representing less error), as compared to111.5 and 7.85 for females. Importantly, we found that the RFT mediates the sex difference in IQ, and that the factor loadings of the RFT on the g factor increases with age, from −0.06 at age 4 to −0.52 at 11 and −0.67 at age 18. In conclusion, g becomes more integrative of spatial ability across time and this finding may explain sex differences in g after puberty and potentially has interesting implications for the understanding of the development of intelligence. One important direction for future research is to incorporate biologically based pubertal neural changes into our understanding of developmental sex differences in intelligence.

Cognitive reserve protects language functions in patients with brain tumours

Cognitive reserve (CR) theory suggests that individual differences in general intelligence (IQ), occupational attainment or participation in leisure/recreational activities protect against cognitive decline. However the relationship between CR and cognitive functioning in patients with brain tumours has been very rarely investigated in past research. The present study systematically assesses whether CR concept can also be applied to cognitive functions of neurosurgical patients affected by brain tumours. We investigated the role of different CR proxies (education level, premorbid IQ, current IQ, working and leisure activity) in protecting language against brain tumours and surgery effects, considering interactions with demographic (sex/age), anatomical (hemisphere/lobe location of lesion) and clinical/biological variables (tumour type: High/Low Grade Glioma or Meningioma; lesion volume; lesion aggressiveness). One-hundred patients undergoing neuropsychological assessment before and immediately after surgery participated. A “Language Score” summarizing performance on all language tests was derived with Principal Component Analysis. Data were then analyzed with Multiple Regression and Classification and Regression Tree analyses to investigate possible relationships between predictors (CR proxies and clinical variables) and Language Score. We found that premorbid IQ was the best predictor of pre-operatory language integrity, above and beyond all clinical variables considered, also moderating lesion volume effects. Moreover, patients with lower pre-operatory language integrity and low-to-moderately aggressive tumours showed a mitigating effect of current IQ over surgery consequences. Results thus suggest that different CR proxies play a role in moderating cognitive decline following brain tumours and surgery.

A Study of Teacher Effectiveness, General Intelligence and Creativity of Secondary School Teachers

The present study attempts to compare teacher effectiveness, general intelligence and creativity of secondary school teachers in relation to gender and type of school. The sample for the study consisted of 850 secondary school teachers of Punjab. The findings of the study revealed that there is no significant difference in teacher effectiveness of male and female secondary school teachers. The significant main effect of type of school is independent of gender groups, i.e. government school teachers are effective both in case of male and female groups of school teachers. There is significant difference in general intelligence of male and female secondary school teachers, female teachers being more intelligent as compared to male teachers, both in case of government and private schools. The results also show that male teachers of private secondary schools are more creative than female teachers of private secondary schools but not in case of government secondary schools. Government school teachers are significantly high on creativity than private school teachers only in case of female group and not in case of male teachers. Teacher effectiveness is positively and significantly related with general intelligence and creativity among secondary school teachers.

Neuroenergetics and "General Intelligence": A Systems Biology Perspective.

David C. Geary proposed the efficiency of mitochondrial processes, especially the production of energy, as the most fundamental biological mechanism contributing to individual differences in general intelligence (g). While the efficiency of mitochondrial functioning is undoubtedly an important and highly interesting factor, I outline several reasons why other main factors of neuroenergetics should not be neglected and why a systems biology perspective should be adopted. There are many advantages for research on intelligence to focus on individual differences in the capability of the overall brain metabolism system to produce the energy currency adenosine triphosphate (ATP): higher predictive strength than single mechanisms, diverse possibilities for experimental manipulation, measurement with existing techniques and answers to unresolved questions because of multiple realizability. Many of these aspects are especially important for research on developmental processes and the building and refining of brain networks for adaptation. Focusing too much on single parts of the system, like the efficiency of mitochondrial functioning, carries the danger of missing important information about the role of neuroenergetics in intelligence and valuable research opportunities.

Mitochondria as the Linchpin of General Intelligence and the Link between g, Health, and Aging.

In a recent theoretical article, I proposed that the efficiency of mitochondrial functioning is the most fundamental biological mechanism contributing to individual differences in general intelligence (g; Geary, 2018). The hypothesis accommodates other contributing mechanisms at higher levels of analysis (e.g., brain networks), and is attractive because mitochondrial energy production undergirds the developmental, maintenance, and expression of these other mechanisms and provides a means to link individual differences in g to individual differences in health and successful aging in adulthood. I provide a brief summation here and a few clarifications to the original article.

Predicting piano skill acquisition in beginners: The role of general intelligence, music aptitude, and mindset

This study was designed to investigate sources of individual differences in musical skill acquisition. We had 171 undergraduates with little or no piano-playing experience attempt to learn a piece of piano music with the aid of a video-guide, and then, following practice with the guide, attempt to perform the piece from memory. A panel of musicians evaluated the performances based on their melodic and rhythmic accuracy. Participants also completed tests of working memory capacity, fluid intelligence, crystallized intelligence, processing speed, and two tests of music aptitude (the Swedish Music Discrimination Test and the Advanced Measures of Music Audiation). Measures of general intelligence and music aptitude correlated significantly with skill acquisition, but mindset did not. Structural equation modeling revealed that general intelligence, music aptitude, and mindset together accounted for 22.4% of the variance in skill acquisition. However, only general intelligence contributed significantly to the model (β = 0.44, p < .001). The contributions of music aptitude (β = 0.08, p = .39) and mindset (β = −0.06, p = .50) were non-significant after accounting for general intelligence. We also found that openness to experience did not significantly predict skill acquisition or music aptitude. Overall, the results suggest that after accounting for individual differences in general intelligence, music aptitude and mindset do not predict piano skill acquisition in beginners.

Faster, but not smarter: An experimental analysis of the relationship between mental speed and mental abilities

Individual differences in the speed of information processing may contribute to individual differences in general intelligence by enhancing the efficiency of information processing. So far, this hypothesis is based on correlational data, and thus a causal relationship between mental speed and mental abilities has not yet been established. In the present study, we used transdermal nicotine administration in a double-blind design to increase the speed of information processing and tested whether this increase in information processing speed affected performance in intelligence tests. While nicotine administration decreased both reaction times and P3 latencies in the Sternberg memory scanning task, there was no effect of nicotine on intelligence test performance. These results contradict theories proposing that a greater speed of information processing causes greater intelligence. Instead, they suggest that structural properties of the brain may affect both the speed of information processing and general intelligence and may thus give rise to the well-established association between mental speed and mental abilities.

Is general intelligence little more than the speed of higher-order processing?

Individual differences in the speed of information processing have been hypothesized to give rise to individual differences in general intelligence. Consistent with this hypothesis, reaction times (RTs) and latencies of event-related potential have been shown to be moderately associated with intelligence. These associations have been explained either in terms of individual differences in some brain-wide property such as myelination, the speed of neural oscillations, or white-matter tract integrity, or in terms of individual differences in specific processes such as the signal-to-noise ratio in evidence accumulation, executive control, or the cholinergic system. Here we show in a sample of 122 participants, who completed a battery of RT tasks at 2 laboratory sessions while an EEG was recorded, that more intelligent individuals have a higher speed of higher-order information processing that explains about 80% of the variance in general intelligence. Our results do not support the notion that individuals with higher levels of general intelligence show advantages in some brain-wide property. Instead, they suggest that more intelligent individuals benefit from a more efficient transmission of information from frontal attention and working memory processes to temporal-parietal processes of memory storage. (PsycINFO Database Record

Resting state functional connectivity correlates of emotional awareness

Multiple neuroimaging studies have now linked emotional awareness (EA), as measured by the Levels of Emotional Awareness Scale (LEAS), with activation in regions of neural networks associated with both conceptualization (i.e., default mode network [DMN] regions) and interoception (i.e., salience network [SN] regions) – consistent with the definition of EA as one's ability to appropriately recognize, conceptualize, and articulate the emotions of self and other in fine-grained, differentiated ways. However, no study has yet tested the hypothesis that greater LEAS scores are associated with greater resting state functional connectivity (FC) within these networks. Twenty-six adults (13 female) underwent resting state functional magnetic resonance imaging, and also completed the LEAS. Using pre-defined functional ROIs from the DMN and SN, we observed that LEAS scores were significantly positively correlated with FC between several regions of both of these networks, even when controlling for differences in general intelligence (IQ). These results suggest that higher EA may be associated with more efficient information exchange between brain regions involved in both interoception- and conceptualization-based processing, which could plausibly contribute to more differentiated bodily feelings and more fine-grained conceptualization of those feelings.

Sex differences in brain size and general intelligence (g)

Utilizing MRI and cognitive tests data from the Human Connectome project (N=900), sex differences in general intelligence (g) and molar brain characteristics were examined. Total brain volume, cortical surface area, and white and gray matter correlated 0.1–0.3 with g for both sexes, whereas cortical thickness and gray/white matter ratio showed less consistent associations with g. Males displayed higher scores on most of the brain characteristics, even after correcting for body size, and also scored approximately one fourth of a standard deviation higher on g. Mediation analyses and the Method of Correlated Vectors both indicated that the sex difference in g is mediated by general brain characteristics. Selecting a subsample of males and females who were matched on g further suggest that larger brains, on average, lead to higher g, whereas similar levels of g do not necessarily imply equal brain sizes.

Sex Differences in Intelligence: A Genetics Perspective

Richard Lynn’s paper on the existence and the magnitude of sex differences in general intelligence proposes that among adults men have a higher average IQ than women and greater variability, and these contribute to the greater number of men among high achievers. The greater variability of males may be attributable to X-linked transmission of intelligence and/or to higher testosterone that could increase the expression of genes related to neurological development or cognition. Key Words: Intelligence, Sex differences, X-linked inheritance

Sex differences in the intellectual functioning of early school-aged children in rural China.

BackgroundGender disparities in China are concentrated in poor rural areas and among poor households. The difference in intelligence between boys and girls is less clear in rural China. The purpose of this paper was to assess sex differences in the intellectual function of early school-aged children in rural China.MethodsOne thousand seven hundred forty four early school-aged offspring of women who had participated in a prenatal supplementation trial with different combinations of micronutrients and continued to reside in two rural counties in China were followed. We measured their Full-Scale IQ (FSIQ), Verbal Comprehension Index (VCI), Working Memory Index (WMI), Perceptual Reasoning Index (PRI) and Processing Speed Index (PSI) using the Wechsler Intelligence Scale for Children (WISC-IV). Multilevel analyses were used to assess sex differences in intellectual functioning in 7-10-year-old children in rural China.ResultsBoys’ adjusted mean FSIQ score was 0.97 points higher (95 % CI: -2.22 − 0.28) than that of girls. Girls obtained higher mean WMI and PSI scores, with 1.32 points (95 % CI: 0.14 − 2.51) and 3.10 points (95 % CI: 1.82–4.38) higher adjusted means, respectively. Boys’ adjusted mean VCI and PRI scores were significantly higher than those of girls, and the mean differences were 2.44 points (95 % CI: 0.95 − 3.94) and 3.68 points (95 % CI: 2.36 − 5.01), respectively.ConclusionsThere is no evidence to suggest sex differences in the general intelligence of early school-aged children in rural China. However, a difference in general intelligence between 10-year-old boys and girls was evident. Girls and boys in rural China tended to show different specific cognitive abilities.

The impact of bilingualism on cognitive ageing and dementia

Abstract Within the current debates on cognitive reserve, cognitive ageing and dementia increasingly showing a positive effect of mental, social and physical activities on health in older age, bilingualism remains one of the most controversial issues. Some reasons for it might be social or even ideological. However, one of the most important genuine problems facing bilingualism research is the high number of potential confounding variables. Bilingual communities often differ from monolingual ones in a range of genetic and environmental variables. In addition, within the same population, bilingual individuals could be different from the outset from those who remain monolingual. We discuss the most common confounding variables in the study of bilingualism, aging and dementia, such as group heterogeneity, migration, social factors, differences in general intelligence and the related issue of reverse causality. We describe different ways in which they can be minimised by the choice of the studied populations and the collected data. In this way, the emerging picture of the interaction between bilingualism and cognitive aging becomes more complex, but also more convincing.

Reduced short term memory in congenital adrenal hyperplasia (CAH) and its relationship to spatial and quantitative performance

Girls and women with classical congenital adrenal hyperplasia (CAH) experience elevated androgens prenatally and show increased male-typical development for certain behaviors. Further, individuals with CAH receive glucocorticoid (GC) treatment postnatally, and this GC treatment could have negative cognitive consequences. We investigated two alternative hypotheses, that: (a) early androgen exposure in females with CAH masculinizes (improves) spatial perception and quantitative abilities at which males typically outperform females, or (b) CAH is associated with performance decrements in these domains, perhaps due to reduced short-term-memory (STM). Adolescent and adult individuals with CAH (40 female and 29 male) were compared with relative controls (29 female and 30 male) on spatial perception and quantitative abilities as well as on Digit Span (DS) to assess STM and on Vocabulary to assess general intelligence. Females with CAH did not perform better (more male-typical) on spatial perception or quantitative abilities than control females, failing to support the hypothesis of cognitive masculinization. Rather, in the sample as a whole individuals with CAH scored lower on spatial perception (p≤.009), a quantitative composite (p≤.036), and DS (p≤.001), despite no differences in general intelligence. Separate analyses of adolescent and adult participants suggested the spatial and quantitative effects might be present only in adult patients with CAH; however, reduced DS performance was found in patients with CAH regardless of age group. Separate regression analyses showed that DS predicted both spatial perception and quantitative performance (both p≤.001), when age, sex, and diagnosis status were controlled. Thus, reduced STM in CAH patients versus controls may have more general cognitive consequences, potentially reducing spatial perception and quantitative skills. Although hyponatremia or other aspects of salt-wasting crises or additional hormone abnormalities cannot be ruled out as potential contributors, elevated GCs appear to be the most likely contributor to reductions in STM. Additional efforts to monitor GC administration protocols may help achieve optimal cognitive outcomes. Educational intervention for individuals with CAH might also be useful.

Can we reliably measure the general factor of intelligence (g) through commercial video games? Yes, we can!

Here we show, for the very first time, that commercial video games can be used to reliably measure individual differences in general intelligence (g). One hundred and eighty eight university undergraduates took part in the study. They played twelve video games under strict supervision in the laboratory and completed eleven intelligence tests. Several factor models were tested for answering the question of whether or not video games and intelligence tests do measure the same underlying high-order latent factor. The final model revealed a very high relationship between the high-order latent factors representing video game and intelligence performance (r=.93). General performance scores derived from video games and intelligence tests showed a correlation value of .963 (R2adjusted). Therefore, performance on some video games captures a latent factor common to the variance shared by cognitive performance assessed by standard ability tests.

Sex differences across different racial ability levels: Theories of origin and societal consequences

Jensen (1971) found that black girls score 3 IQ points higher than black boys, and white boys 1.5 IQ points higher than white girls. He, nevertheless, concluded that this did not support his Race×Sex×Ability interaction theory. Jensen (1998) further analyzed data, some from the National Longitudinal Survey of Youth (NLSY79), and suggested that there is no sex difference in general intelligence, g. Other studies have questioned Jensen's null sex difference theory.The present study tested both theories with data from the ensuring NLSY97 survey, which represents the 15+ million 12–17year old adolescents living in the US in 1997.Total sample analyses confirmed the existence of significant inverse white–black IQ sex differences, and disconfirmed the null sex difference theory.Separate race–age analyses demonstrated, however, that robust IQ sex differences materialize only after age 16, with no white–black interaction. At age 17, female IQ trails male by 3.6–7.03 points in three races, respectively.Classical IQ probability curves foretell that more males than females will enter the highest echelons of society, irrespective of race, and white Male/Female ratios at IQ 145 successfully predicted real-life sex differences in educational and occupational achievement. White males with IQ 55 can be expected to run a very high risk of encountering severe achievement problems, a risk shared to some extent with Hispanic male, but black females with this low IQ can be expected to perform worse than black males.The paper finally proposed models to account for the origin of sex and race differences in IQ and related educational and occupational differences, involving gene copy numbers, brain size, and steroid hormones. It was suggested that the evolutionary background and physiological nature of sex and race differences explain why social engineering fails to eradicate them.