The future of intelligence: The role of specific abilities

Mental health of intellectually gifted individuals: investigating the nonlinearity of the relationship between intelligence and general mental health

BACKGROUND

Despite intelligence being generally related to better mental health, individuals with extremely high levels of intelligence (also often referred to as gifted) are frequently viewed to be socially maladjusted, emotionally unstable, and eccentric. Although this view has existed for decades, the scientific data on this subject are highly inconsistent and suffer from several methodological limitations.

PARTICIPANTS AND PROCEDURE

In this study, to test whether the relationship between general intelligence and general mental health is nonlinear in such a way that at extreme values of intelligence the relationship turns from positive to negative the data from eight waves of the 1970 British Cohort Study (BCS70) were used (N range from 2,870 to 7,984), with intelligence being assessed at age 10, and mental health being assessed with several different measures at ages 16, 26, 30, 34, 42, 46 and 50. Quadratic regression, as well as spline regression, which divides the dataset into intervals, creates a separate regression for each interval and then smooths out the breakpoints, was used for analyses.

RESULTS

The results showed that the nonlinear models generally fit the data better than the corresponding linear models.

CONCLUSIONS

At high values of intelligence, individuals might begin to experience unique issues affecting their mental health, despite their mental health being at potentially the same or higher level than those with average intelligence. Intellectually gifted individuals have a large potential to have a positive impact on the functioning of the whole society. Recognizing and understanding their problems may prove to be of great importance.

The Evolution of Intelligence: Analysis of the Journal of Intelligence and Intelligence

What are the current trends in intelligence research? This parallel bibliometric analysis covers the two premier journals in the field: Intelligence and the Journal of Intelligence (JOI) between 2013 and 2022. Using Scopus data, this paper extends prior bibliometric articles reporting the evolution of the journal Intelligence from 1977 up to 2018. It includes JOI from its inception, along with Intelligence to the present. Although the journal Intelligence's growth has declined over time, it remains a stronghold for traditional influential research (average publications per year = 71.2, average citations per article = 17.07, average citations per year = 2.68). JOI shows a steady growth pattern in the number of publications and citations (average publications per year = 33.2, average citations per article = 6.48, total average citations per year = 1.48) since its inception in 2013. Common areas of study across both journals include cognitive ability, fluid intelligence, psychometrics-statistics, g-factor, and working memory. Intelligence includes core themes like the Flynn effect, individual differences, and geographic IQ variability. JOI addresses themes such as creativity, personality, and emotional intelligence. We discuss research trends, co-citation networks, thematic maps, and their implications for the future of the two journals and the evolution and future of the scientific study of intelligence.

The genetics of specific cognitive abilities

Most research on individual differences in performance on tests of cognitive ability focuses on general cognitive ability (g), the highest level in the three-level Cattell-Horn-Carroll (CHC) hierarchical model of intelligence. About 50% of the variance of g is due to inherited DNA differences (heritability) which increases across development. Much less is known about the genetics of the middle level of the CHC model, which includes 16 broad factors such as fluid reasoning, processing speed, and quantitative knowledge. We provide a meta-analytic review of 747,567 monozygotic-dizygotic twin comparisons from 77 publications for these middle-level factors, which we refer to as specific cognitive abilities (SCA), even though these factors are not independent of g. Twin comparisons were available for 11 of the 16 CHC domains. The average heritability across all SCA is 56%, similar to that of g. However, there is substantial differential heritability across SCA and SCA do not show the developmental increase in heritability seen for g. We also investigated SCA independent of g (SCA.g). A surprising finding is that SCA.g remain substantially heritable (53% on average), even though 25% of the variance of SCA that covaries with g has been removed. Our review highlights the need for more research on SCA and especially on SCA.g. Despite limitations of SCA research, our review frames expectations for genomic research that will use polygenic scores to predict SCA and SCA.g. Genome-wide association studies of SCA.g are needed to create polygenic scores that can predict SCA profiles of cognitive abilities and disabilities independent of g.