Intelligence: genetics, genes, and genomics

More is known about the genetics of intelligence than about any other trait, behavioral or biological, which is selectively reviewed in this article. Two of the most interesting genetic findings are that heritability of intelligence increases throughout the life span and that the same genes affect diverse cognitive abilities. The most exciting direction for genetic research on intelligence is to harness the power of the Human Genome Project to identify some of the specific genes responsible for the heritability of intelligence. The next research direction will be functional genomics--for example, understanding the brain pathways between genes and intelligence. Deoxyribonucleic acid (DNA) will integrate life sciences research on intelligence; bottom-up molecular biological research will meet top-down psychological research in the brain.     

Human values: Genetic and environmental effects on five lexically derived domains and their facets

Whereas a substantial genetic component of Conservatism and Religiosity is well documented, there is little evidence with respect to the behavior genetics of other aspects of human values. A sample of 157 monozygotic and 74 dizygotic twins reared together received the Austrian Value Questionnaire (AVQ), which measures a broad variety of value domains and their facets, found by the lexical approach in the German language. Family resemblance of Intellectualism, Harmony, Materialism, and Conservatism was best explained by additive or dominance genetic and non-shared environmental effects, whereas the influence of the environment shared by twins was negligible. In contrast, Religiosity was transmitted by additive genetic, shared and non-shared environmental influences. At the level of facets, the Intellectualism and Harmony showed a homogenous etiology while Religiosity, Materialism, and Conservatism were etiologically heterogeneous.     

Predicting school achievement from cognitive and non-cognitive variables in a Chinese sample of elementary school children

The present study had two aims: First, to investigate the joint and specific roles of working memory (WM) and intelligence as predictors of school achievement. And second, to replicate and extend earlier findings (Spinath, Spinath, Harlaar, & Plomin, 2006) on the incremental validity of non-cognitive over cognitive abilities in the prediction of school achievement. The present sample consisted of N = 179 Chinese primary school children in the fourth grade. All measures including working memory (WM), intelligence and motivational items were assessed in class. Teachers provided test scores for the domains of Chinese and Math. We found that WM was a good predictor of school achievement and comparable in predictive power to intelligence. Together, cognitive ability including both WM and intelligence explained 17.8% and 36.4% of the variance in children's Chinese and Math scores, respectively. The relative importance of WM and intelligence varied with school domains with greater predictive power of WM for Math while intelligence explained a greater proportion of the variance in Chinese although the magnitude of this difference was only moderate. Domain-specific motivational constructs contributed only marginally to the prediction of school achievement for both Chinese and Math.     

Is the genetic structure of human personality universal? A cross-cultural twin study from North America, Europe, and Asia

This study examined whether universality of the 5-factor model (FFM) of personality operationalized by the Revised NEO Personality Inventory is due to genetic influences that are invariant across diverse nations. Factor analyses were conducted on matrices of phenotypic, genetic, and environmental correlations estimated in a sample of 1,209 monozygotic and 701 dizygotic twin pairs from Canada, Germany, and Japan. Five genetic and environmental factors were extracted for each sample. High congruence coefficients were observed when phenotypic, genetic, and environmental factors were compared in each sample as well as when each factor was compared across samples. These results suggest that the FFM has a solid biological basis and may represent a common heritage of the human species.     

Burnout risk among first-year teacher students: The roles of personality and motivation

The present study identified individual variables by which first-year teacher students' risk for burnout can be detected at an early stage. We analyzed a sample of teacher students (n = 559) and a control group of psychology students (n = 150) by using multinomial logistic regression analyses. We estimated the impact of personality (Five-Factor model) and motivation for choosing teacher education on work-related coping behavior and experiences (WCEP types: healthy-ambitious, unambitious, excessively-ambitious, and risk for burnout). Neuroticism and the extrinsic motivation of choosing teacher education (the assumed low difficulty of studies) were risk factors for unhealthy, stress-related coping behavior and experiences. In contrast, high levels of extraversion and conscientiousness as well as intrinsic motivation for choosing teacher education (subject-specific interest) were related to healthy-ambitious behavior. Relations of personality and stress-related WCEP types were partially moderated according to field of study (teaching versus psychology). Our results are of particular importance for improving counseling programs that advise prospective teacher students regarding their individual fit to the requirements and challenges of the teaching profession and for correcting false expectations about study demands.     

What Explains Boys’ Stronger Confidence in their Intelligence?

This study investigated whether boys’ stronger confidence in their intelligence is explained by gender differences in measured intelligence and gender-stereotypical parental perceptions of their children’s intelligence. Verbal, numeric, figural, and reasoning intelligence and corresponding self-ratings were assessed for 496 German 11th and 12th graders (284 girls; age: M?=?16.95). Parents also rated their children’s intelligence (339 parents; 205 mothers; age: M?=?46.66). With and without controlling for intelligence, boys rated their numerical, figural, and reasoning abilities higher than girls. The same pattern appeared in parental intelligence perceptions. Boys even judged themselves as more intelligent controlling for both measured intelligence and parental intelligence estimates. Thus, neither intelligence nor gender-stereotypical parental perceptions totally explains boys’ stronger confidence in their intelligence.     

Thin slices of behavior as cues of personality and intelligence

Self-reports, peer reports, intelligence tests, and ratings of personality and intelligence from 15 videotaped episodes were collected for 600 participants. The average cross-situational consistency of trait impressions across the 15 episodes was .43. Shared stereotypes related to gender and age were mostly accurate and contributed little to agreement among judges. Agreement was limited mainly by nonshared meaning systems and by nonoverlapping information. Personality inferences from thin slices of behavior were significantly associated with reports by knowledgeable informants. This association became stronger when more episodes were included, but gains in prediction were low beyond 6 episodes. Inferences of intelligence from thin slices of behavior strongly predicted intelligence test scores. A particularly strong single predictor was how persons read short sentences.     

Genetic and environmental influences on Person x Situation profiles

Genetic and environmental influences on Person x Situation interactions were studied using data of the German Observational Study of Adult Twins. The performance of 168 monozygotic and 132 dizygotic twin pairs in 15 tasks was observed by 120 judges who never met the twins in person. Four judges observed one twin of each pair in one task. Twin similarities in Person x Situation profiles were analyzed via (a) correlations across tasks between co-twins' Person x Situation profiles (their personality signatures) and (b) common-pathway genetic models that partitioned genetic and environmental contributions to trait levels and to Person x Situation interactions. Genes accounted for about 25% of the reliable Person x Situation interactions, whereas shared environmental influences were negligible.     

Assessment of Anxiety in Older Adults: Translation and Psychometric Evaluation of the German Version of the Geriatric Anxiety Scale (GAS)

Anxiety occurs frequently among older adults, and can have deleterious impacts on the quality of daily life. Due to the dearth of well-validated elder-specific anxiety screening instruments available in the German language, this study aimed to translate the Geriatric Anxiety Scale (GAS), a reliable and valid 30-item self-report screening instrument for assessing anxiety based on DSM-IV-TR diagnostic criteria (Segal et al. Journal of Anxiety Disorders, 24(7), 709–714, 2010a), into German, and to validate the new measure. The German version of the GAS was developed through a translation and back translation process, with careful attention paid to culturally-sensitive expressions of anxiety in the German older adult population. The final version of the German GAS was tested in a sample of 242 community-dwelling older adults (M_age?=?72.0 years, SD?=?6.9 years; 59 % women) who completed either an online (26 %) or a paper-pencil (74 %) version of the questionnaire. The findings confirmed the successful translation of the GAS into German and provided psychometric support for the new measure. The validation of the factor structure based on confirmatory factor analyses was in support of a unidimensional structure of the GAS-G. Correlational analyses with inventories measuring anxiety related and non-anxiety related personality traits additionally confirmed the convergent and discriminant validity of the GAS for use as an assessment measure for anxiety among German older adults.     

The Heritability of Job Satisfaction Reconsidered: Only Unique Environmental Influences Beyond Personality

Purpose

The purpose of this study was to investigate the degree to which genetic and environmental influences explain differences in job satisfaction and its relationship to personality in order to explain the heritability of job satisfaction.

Design

Behavior genetic analyses are based on a dataset containing 622 individuals, including 185 MZ (M = 39.5 years) and 126 DZ twin pairs (M = 40.1 years).

Findings

The results showed that all genetic influences (28 %) on job satisfaction could be explained by its relation to personality, especially Neuroticism, Extraversion, and Conscientiousness, representing a high genetic overlap between job satisfaction and personality. Non-shared environmental influences explained the remaining three fourths of the variance.

Implications

By showing that genetic influences of job satisfaction overlap completely with personality, including common non-additive genetic influences, the results support an interactionist view of job satisfaction in that both situational and dispositional determinants of job satisfaction are relevant.

Originality

In contrast to previous studies, we used a more appropriate behavior genetic approach meaning that our approach allows to directly estimate parameters of specific and common (additive and non-additive) genetic and environmental influences. Building on this, interpretations of behavior genetic findings were explained in detail to avoid common misunderstandings.