Elisabeth Hahn

Internet addiction and its facets: The role of genetics and the relation to self-directedness

A growing body of research focuses on problematic behavior patterns related to the use of the Internet to identify contextual as well as individual risk factors of this new phenomenon called Internet addiction (IA). IA can be described as a multidimensional syndrome comprising aspects such as craving, development of tolerance, loss of control and negative consequences. Given that previous research on other addictive behaviors showed substantial heritability, it can be expected that the vulnerability to IA may also be due to a persons genetic predisposition. However, it is questionable whether distinct components of IA have different etiologies. Using data from a sample of adult monozygotic and dizygotic twins and non-twin siblings (N=784 individuals, N=355 complete pairs, M=30.30years), we investigated the magnitude of genetic and environmental influences on generalized IA as well as on specific facets such as excessive use, self-regulation, preference for online social interaction or negative consequences. To explain the heritability in IA, we further examined the relation to Self-Directedness as potential mediating source. Results showed that relative contributions of genetic influences vary considerable for different components of IA. For generalized IA factors, individual differences could be explained by shared and non-shared environmental influences while genetic influences did not play a role. For specific facets of IA and private Internet use in hours per week, heritability estimates ranged between 21% and 44%. Bivariate analysis indicated that Self-Directedness accounted for 20% to 65% of the genetic variance in specific IA facets through overlapping genetic pathways. Implications for future research are discussed.

The Role of Nature and Nurture for Individual Differences in Primary Emotional Systems: Evidence from a Twin Study.

The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS) by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings), moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33%) and highest for the PLAY system (69%). Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research.

Current twin studies in Germany: report on CoSMoS, SOEP, and ChronoS.

This article summarizes the status of three recent German twin studies: CoSMoS, SOEP, and ChronoS. The German twin study on Cognitive Ability, Self-Reported Motivation, and School Achievement (CoSMoS) is a three-wave longitudinal study of monozygotic and dizygotic twins reared together, and aims to investigate predictors of and influences on school performance. In the first wave of the data collection in 2005, 408 pairs of twins aged between 7 and 11 as well as their parents participated in CoSMoS. The SOEP twin study is an extended twin study, which has combined data from monozygotic and dizygotic twins reared together with additional data from full sibling pairs, mother-child, and grandparent-child dyads who participated in the German Socio-Economic Panel (GSOEP) study. The SOEP twin project comprises about 350 twin and 950 non-twin pairs aged between 17 and 70. Data were collected between 2009 and 2010, with a focus on personality traits, wellbeing, education, employment, income, living situation, life-satisfaction, and several attitudes. The aim of the Chronotype twin study (ChronoS) was to examine genetic and environmental influences on chronotype (morningness and eveningness), coping strategies, and several aspects of the previous SOEP twin project in a sample of 301 twin pairs aged between 19 and 76 years, recruited in 2010 and 2011. Part of the ChronoS twin sample also participated in the earlier SOEP twin study, representing a second wave of assessments. We briefly describe the design and contents of these three studies as well as selected recent findings.

Income Inequality, Life Satisfaction, and Economic Worries:

We analyzed the effect of income inequality on Germans’ life satisfaction considering factors explaining the mechanism of this relationship. Based on data from the German Socio-Economic Panel Study for the years 1984 to 2012, we found a negative relationship between national-level income disparity and average life satisfaction, meaning that people felt happier in years with lower inequality. The effect was completely mediated by economic worries, which increased with rising inequality and in turn reduced people’s satisfaction. However, people’s reaction to inequality depended on their income level: Considering the direct effect of inequality, higher income disparity was clearly detrimental only for the poor and the middle class. Moreover, we found a significant mediation through economic worries for the middle class but not for the poor. The rich showed a more complex pattern of interrelations with both, positive and negative effects of inequality when controlling for economic worries.

How distinctive are morningness and eveningness from the Big Five factors of personality? A meta-analytic investigation.

This study explores relations between measures of individuals’ circadian preferences and the Big Five. To this end, we compared a model of circadian preferences that acknowledges morningness (M) and eveningness (E) as separate dimensions to that of a model that places M and E on a single continuum (M-E). Analyses of 620 correlations from 44 independent samples (N = 16,647) revealed weak to modest relations between both dimensions of circadian preferences and the Big Five personality traits. The strongest observed relation was found between Conscientiousness and M (&rgr; = .37). In the next step, regression analyses revealed that personality traits accounted for between 10.9% and 16.4% of the variance in circadian preferences. Of all the Big Five dimensions, Conscientiousness exhibited the strongest unique relation with M (&bgr; = .32), E (&bgr; = −.26), and M-E (&bgr; = .32). Extraversion and Openness exhibited moderate unique relations with E (&bgr; = .23 and &bgr; = .17, respectively), whereas relations with M (&bgr; = .00 and &bgr; = .04), and M-E (&bgr; = −.05 and &bgr; = −.06) were relatively weak. Neuroticism exhibited a modest unique and negative relation with M (&bgr; = −.16), and Agreeableness was largely unrelated to all circadian preference variables. To determine whether these findings translated into anything of applied significance, we explored relations between circadian preference and academic performance. M and E incremented slightly over the Big Five factors in predicting grade-point average. Theoretical and practical implications of these findings are discussed.

Coping With Unemployment: The Impact of Unemployment Duration and Personality on Trajectories of Life Satisfaction

Unemployment is a major life event that causes an enormous drop in peoples life satisfaction. However, there is substantial variability in peoples ability (or inability) to cope with the experience of unemployment. In the present study, we examined the causes of individual differences in trajectories of life satisfaction when people were faced with unemployment by taking into account the persistence of unemployment, pre–event personality and age. Analyses were based on data from the German Socio–Economic Panel. Using latent growth curve modelling, life satisfaction was investigated from 3 years before to 3 years after a person became unemployed in a total sample of 908 individuals. As expected, unemployment caused a substantial drop in life satisfaction that persisted for at least 3 years after the event. On average, individuals did not completely return to their previous satisfaction level. This pattern existed even for participants who re–entered the labour market. Moreover, our results showed that variability in coping with unemployment can be explained in part by personality traits. For people with short periods of unemployment, Conscientiousness reinforced the negative effect of unemployment, whereas Extraversion softened the effect. In sum, our analyses showed that (a) the negative effect of unemployment on life satisfaction differs according to the length of the unemployment period and (b) personality partially moderates responses to unemployment over time. Copyright

Quantitative Behavior Genetics of Internet Addiction

It is now well established that all human traits are influenced both by genes and the environment. This suggests that most relationships, such as the relationship between personality and Internet addiction, may be due in part to genetic influences. To reach a more complete understanding of the risk factors associated with the initiation and maintenance of Internet addiction, the dynamic interplay of genes and environment over the life course must be investigated to allow for the identification of potential developmental changes linked to genetic vulnerabilities and resilience. In this chapter, we highlight behavior genetic research approaches and findings with respect to Internet addiction (In line with the editors of this book, we use the term Internet addiction as an umbrella term encompassing different conceptualizations and understandings of the phenomenon of problematic Internet use.) and related constructs. We will outline how genetically informative data can provide new and promising insights into the understanding of underlying sources of individual differences in Internet addiction. Future research questions will also be discussed.

Does the heritability of cognitive abilities vary as a function of parental education? Evidence from a German twin sample

A well-known hypothesis in the behavioral genetic literature predicts that the heritability of cognitive abilities is higher in the presence of higher socioeconomic contexts. However, studies suggest that the effect of socioeconomic status (SES) on the heritability of cognitive ability may not be universal, as it has mostly been demonstrated in the United States, but not in other Western nations. In the present study we tested whether the importance of genetic and environmental effects on cognitive abilities varies as a function of parental education in a German twin sample. Cognitive ability scores (general, verbal, and nonverbal) were obtained on 531 German twin pairs (192 monozygotic, 339 dizygotic, ranging from 7 to 14 years of age; Mage = 10.25, SD = 1.83). Data on parental education were available from mothers and fathers. Results for general cognitive ability and nonverbal ability indicated no significant gene x parental education interaction effect. For verbal ability, a significant nonshared environment (E) x parental education interaction was found in the direction of greater nonshared environmental influences on verbal abilities among children raised by more educated parents.