For researchers and practitioners interested in social relationships, the question remains as to how large social networks typically are, and how their size and composition change across adulthood. On the basis of predictions of socioemotional selectivity theory and social convoy theory, we conducted a meta-analysis on age-related social network changes and the effects of life events on social networks using 277 studies with 177,635 participants from adolescence to old age. Cross-sectional as well as longitudinal studies consistently showed that (a) the global social network increased up until young adulthood and then decreased steadily, (b) both the personal network and the friendship network decreased throughout adulthood, (c) the family network was stable in size from adolescence to old age, and (d) other networks with coworkers or neighbors were important only in specific age ranges. Studies focusing on life events that occur at specific ages, such as transition to parenthood, job entry, or widowhood, demonstrated network changes similar to such age-related network changes. Moderator analyses detected that the type of network assessment affected the reported size of global, personal, and family networks. Period effects on network sizes occurred for personal and friendship networks, which have decreased in size over the last 35 years. Together the findings are consistent with the view that a portion of normative, age-related social network changes are due to normative, age-related life events. We discuss how these patterns of normative social network development inform research in social, evolutionary, cultural, and personality psychology.

Personality and social relationships were assessed twice across a 4-year period in a general population sample of 489 German young adults. Two kinds of personality-relationship transaction were observed. First, mean-level change in personality toward maturity (e.g., increase in Conscientiousness and decrease in Neuroticism) was moderated by the transition to partnership but was independent of other developmental transitions. Second, individual differences in personality traits predicted social relationships much better than vice versa. Specifically, once initial correlations were controlled for, Extraversion, Shyness, Neuroticism, self-esteem, and Agreeableness predicted change in various qualities of relationships (especially with friends and colleagues), whereas only quality of relationships with preschool children predicted later Extraversion and Neuroticism. Consequences for the transactional view of personality in young adulthood are discussed.

Bayesian statistical methods are becoming ever more popular in applied and fundamental research. In this study a gentle introduction to Bayesian analysis is provided. It is shown under what circumstances it is attractive to use Bayesian estimation, and how to interpret properly the results. First, the ingredients underlying Bayesian methods are introduced using a simplified example. Thereafter, the advantages and pitfalls of the specification of prior knowledge are discussed. To illustrate Bayesian methods explained in this study, in a second example a series of studies that examine the theoretical framework of dynamic interactionism are considered. In the Discussion the advantages and disadvantages of using Bayesian statistics are reviewed, and guidelines on how to report on Bayesian statistics are provided.

Personality-relationship transactions were investigated in a general population sample of young German adults with three assessments over 8 years. Four general findings were obtained. First, personality development was characterized by substantive individual differences in change. Second, bivariate latent growth models indicated that individual differences in personality change were substantially associated with change in peer and family relationships. Third, forming a partner relationship for the first time moderated the maturation of personality. This finding was replicated over two subsequent time intervals with independent subgroups. Fourth, higher neuroticism and higher sociability predicted which of the singles began a partner relationship during the next 8 years. The results confirm that individual differences in personality development predict and result from life transitions and relationship experiences.

International mobility is a prevalent life event that particularly affects university students. The aim of this longitudinal study was twofold: First, we examined the impact of international mobility on personality (Big Five) change, separating self-selection effects from socialization processes. Second, we extended prior analyses on the association between life events and personality development by investigating the mechanisms that account for socialization processes. In particular, we assessed whether individual differences in the fluctuation of support relationships serve as an explanatory link. We used a prospective control group design with 3 measurement occasions. A sample of university students, containing both short-term (i.e., 1 semester) and long-term (i.e., 1 academic year) sojourners (N = 527) along with control students (N = 607), was tracked over the course of an academic year. Multivariate latent models revealed 3 main findings: First, initial (pre-departure) levels of Extraversion and Conscientiousness predicted short-term sojourning, and Extraversion and Openness predicted long-term sojourning. Second, both forms of sojourning were associated with increases in Openness and Agreeableness and a decrease in Neuroticism above and beyond the observed self-selection. Third, the acquisition of new international support relationships largely accounted for the sojourn effects on personality change. These findings help to fill the missing link between life events and personality development by establishing social relationship fluctuation as an important mediating mechanism.