Genetics and general cognitive ability (g)

Two recent articles in this journal made the case for the existence and importance of g and reviewed research on cognitive and psychophysical correlates of psychometric g. This review considers g from a genetic perspective. Multivariate genetic research indicates that g accounts for nearly all of the genetic variance of diverse psychometric cognitive tests (genetic g). Recent research suggests not only that elementary cognitive tasks are genetically linked to psychometric g but also that genetic g pervades these tasks. Contrary to the assumption of modularity that dominates cognitive science, genetic g exists in the mind as well as in psychometric tests.     

Relation of self-talk frequency to loneliness,need to belong,and health in German adults

This study examined whether individuals with a high need to belong and feelings of loneliness tend to compensate for a lack of social contact by self-talk and whether self-talk prevents negative consequences on their physical and mental health. The sample consisted of 559 adults drawn from the German Sozioland Panel Project. The results of SEM analyses revealed evidence for significant relations of the need to belong and loneliness with the frequency of self-talk. Moreover, the need to belong and loneliness were significantly related to mental and physical health, but loneliness was shown to be more important for the prediction of both health outcomes. Results of moderator analyses indicate that self-talk might be a risk factor for an increased negative correlation between loneliness and mental health. Self-talk, which is supposed to be related to self-awareness, might reinforce the subjective feeling of loneliness and hence have a negative impact on psychological well-being.     

Personality in Germany and Minnesota: an IRT-based comparison of MPQ self-reports

We compared personality across cultures to explore the extent of cultural differences. This study used samples matched on gender and age from Germany and Minnesota to compare traditional scale scores and IRT-based parameters for Tellegen's (1982) Multidimensional Personality Questionnaire scales. Because the samples consisted of twins, we were able to replicate the findings from the subsamples consisting of one member of each pair with the subsamples consisting of their co-twins. When the full scales were considered, Germans were higher in Aggression and Absorption and Minnesotans were higher in Well-being, Control, and Traditionalism, but, except for those in Traditionalism, different item-difficulty parameters explained most of these differences. IRT highlighted less than optimal scale properties as well as differentially functioning items. We discuss the theoretical implications of these findings.     

Genetic and environmental influences on girls' and boys' gender-typed and gender-neutral values

In this first investigation of genetic and environmental influences on children's values, 271 German twin pairs (50.2% boys) reported their values at ages 7-11 years using the Portrait Values Questionnaire (Schwartz & Rubel, 2005). We distinguished between gender-neutral (conservation vs. openness to change) and gender-typed (self-transcendence vs. self-enhancement) values. Boys differed from girls in the importance given to gender-typed benevolence, achievement, and power values. Gender-neutral values showed moderate (.34) and gender-typed values showed higher (.49) heritability, with nonshared environment and error accounting for the remaining variance. For both sexes, substantial genetic effects accounted for the importance children gave to their respective gender-stereotypical end of the self-transcendence versus self-enhancement dimension. However, dramatic sex differences emerged in the gender-atypical end of the distribution. For girls, low self-transcendence (high gender-atypical values) showed a large (.76) group heritability. For boys, gender-atypical values (high self-transcendence) showed no heritability and a modest (.10) shared environment effect.     

How heritable is empathy? Differential effects of measurement and subcomponents

Empathy is an important psychological concept influencing social interaction. However, knowledge about its etiological components is still scarce. Estimates for the heritability of empathy range between 0 and 70 % depending on the sample, method of measurement, and level of aggregation. In this study, we investigated the heritability of empathy using an extended twin design. We employed the self-report questionnaire Interpersonal Reactivity Index and an emotion recognition task (Reading the Mind in the Eyes Test). N = 742 twins and non-twin siblings were investigated. For affective empathy and the behavioral paradigm, we found heritability estimates between 52 and 57 %. For cognitive empathy, genetic variance was smaller (27 %), indicating that the heritability of empathy depends on the measured subcomponent, which could be relevant for intervention programs like empathy or compassion trainings. Environmental influences on empathy are mainly effects of non-shared environment, which is an important finding for our understanding of the development of empathy.     

Partnership longevity and personality congruence in couples

Evidence of assortative mating according to personality was reported in a previous SOEP-based study (Rammstedt & Schupp, 2008). Based on population representative data of almost 7000 couples, high levels of congruence between spouses were found, which increased with marriage duration. Almost 5000 of these couples were tracked over a five-year period with personality assessed at the beginning and end of this time, which allowed us to investigate the relationship between personality congruence and marriage duration longitudinally. Using this data, we investigated (a) whether personality congruence is predictive for partnership longevity and whether congruence therefore differs between subsequently stable and unstable couples, (b) if stable couples become more congruent, and (c) if separated couples become less congruent with regard to their personality over time. The results provide initial evidence of personality congruence as a predictor for partnership longevity: the more congruent couples are in the personality domain of Openness, the more stable their partnership. In addition, we found no indications of an increase in personality congruence over time within the stable couples; within the separated couples, however, a strong decrease in congruence was detectable.     

The genetic links between the big five personality traits and general interest domains

This is the first genetically informative study in which multiple informants were used to quantify the genetic and environmental sources of individual differences in general interests as well as the phenotypic and genetic links between general interests and Big Five personality traits. Self-reports and two peer ratings from 844 individuals, including 225 monozygotic and 113 dizygotic complete twin pairs, were collected. Multiple-rater scores (composites) revealed that the averaged levels of genetic and environmental effects on seven broad interest domains were similar to those on personality traits. Multivariate analyses showed that about 35% of the genetic and 9% of the environmental variance in interests were explained by personality domains, in particular by Openness. The findings suggest that interests cannot easily be considered as a byproduct of the interactions between personality genotypes and the environmental influences but rather as an internal regulation of behavior with an own genetic basis.     

Sources of Variance in Personality Facets: A Multiple‐Rater Twin Study of Self‐Peer,Peer‐Peer,and Self‐Self (Dis)Agreement

ABSTRACT This study considered the validity of the personality structure based on the Five‐Factor Model using both self‐ and peer reports on twins' NEO‐PI‐R facets. Separating common from specific genetic variance in self‐ and peer reports, this study examined genetic substance of different trait levels and rater‐specific perspectives relating to personality judgments. Data of 919 twin pairs were analyzed using a multiple‐rater twin model to disentangle genetic and environmental effects on domain‐level trait, facet‐specific trait, and rater‐specific variance. About two thirds of both the domain‐level trait variance and the facet‐specific trait variance was attributable to genetic factors. This suggests that the more personality is measured accurately, the better these measures reflect the genetic structure. Specific variance in self‐ and peer reports also showed modest to substantial genetic influence. This may indicate not only genetically influenced self‐rater biases but also substance components specific for self‐ and peer raters' perspectives on traits actually measured.     

Genetic and environmental influences on observed personality: evidence from the German Observational Study of Adult Twins

Previous behavior-genetic research on adult personality relied primarily on self-reports or peer reports that may be subject to contrast effects, resulting in biased estimates of genetic and environmental influences. In the German Observational Study of Adult Twins (GOSAT), personality traits of 168 monozygotic (MZ) and 132 dizygotic (DZ) twin pairs were rated on 35 adjective scales, largely markers of the Big 5. The ratings were provided by 120 judges who never met the twins but observed videotaped behaviors of 1 twin of each pair in 1 of 15 different settings. The aggregated video-based trait ratings were highly reliable, and substantial correlations were obtained between MZ as well as DZ twins. Model-fit analyses suggested about 40% genetic, 25% shared environmental, and 35% nonshared environmental influence. Extraversion was the only trait that seemed not to be influenced by shared environment.     

Substance and artifact in the higher-order factors of the Big Five

J. M. Digman (1997) proposed that the Big Five personality traits showed a higher-order structure with 2 factors he labeled alpha and beta. These factors have been alternatively interpreted as heritable components of personality or as artifacts of evaluative bias. Using structural equation modeling, the authors reanalyzed data from a cross-national twin study and from American cross-observer studies and analyzed new multimethod data from a German twin study. In all analyses, artifact models outperformed substance models by root-mean-square error of approximation criteria, but models combining both artifact and substance were slightly better. These findings suggest that the search for the biological basis of personality traits may be more profitably focused on the 5 factors themselves and their specific facets, especially in monomethod studies.