Co-Development in Personality in Close Relationships

Human development can be understood as the interaction between biological, sociohistorical, and social conditions, and individual developmental actions. This notion is taken for granted since Havighurst’s (1948) formulation of Developmental Tasks, Erikson’s (1950) description of Life Cycles, and Bronfenbrenner’s (1979)Ecological Systems Theory of Development. In postmodern societies individuals are expected to responsibly control their own life course and sense of well-being. From this perspective, human beings became more than ever architects of their fortune although embedded in contexts. This premise is linked to current theories of personality development, in particular to those that assume a biological basis with an increasing impact of individual actions on personality development across the life span (Caspi & Roberts, 2001; Roberts & Wood, 2006). Individual personality development is interwoven in close dyadic relationships. The crucial importance of close relationships for personality development is highly esteemed and well investigated during the first years of life (e.g., attachment theory, caregiver-child interactions advancing cognitive representations, language, social-emotional competencies, peer relations), but largely neglected after the second decade of life across the life span. However, it is evident that human beings always develop in dyadic relationships, that is, in family dyads across and within generations, in intimate partnerships, at work, or along leisure activities with close friends.

This special issue reviews recent evidence on co-development in personality in close relationships in five domains and answers to which extent and through which processes individual personality development is embedded in dyadic relationships along the life span.

Personality Development

Leading textbooks (e.g., Carver & Scheier, 2008) conceptualize personality as being stable, enduring, and fixed as well as being influenced by experiences in infancy, or influenced by experiences throughout the life span and in mutual exchange with the social world. Other approaches focus on the activity of the individual and assume that people shape their own behavior and their personality. Parallel to these different, partly competing views of personality, a controversy about personality development emerged. The assumption of the stable and unchangeable nature of personality traits was first challenged when Mischel’s (1968) behaviorist critique emphasized the inconsistency of traits stating that personality consistency is due to environmental consistency. With this emphasis personality development became a prominent topic in personality research.

In their seminal contribution, Caspi and Roberts (2001) structured the field of personality development along four elements. The trait model assumes personality as biologically based, heritable dispositions that are not susceptible to environmental influences. Hence, no change or at least no change in interindividual differences in personality over time should occur. In contrast, the contextual model (Mischel & Shoda, 1995) emphasizes the importance of the environment. According to this view, personality consistency results from the consistency of social environments. As a consequence, personality is fluid (at least to some extent) and the potential for change can be observed in particular in periods of social changes. Stage theories (Erikson, 1950) refer to major life changes or life tasks emerging from role transitions and their influence on personality. Finally, the Life Span Development approach (Baltes, 1997) understands individuals as open systems that display personality continuity as well as change throughout the life course. Moreover, psychological and social factors diminish in influence as people get older together with an emerging focus on cognitive factors and motivational strategies to cope with the inevitable decline in functioning that comes with age.

However, most of the aforementioned models are barely suitable to explain findings on personality development from longitudinal studies. These studies reveal that personality traits increase in consistency with age, are mostly consistent in adulthood, and retain the capacity for change throughout the adult life course (Roberts & DelVecchio, 2000). Given the lack of an overarching theory that captures the patterns of personality continuity and change as evidenced by longitudinal studies, Roberts and Wood (2006) proposed principles of personality trait development in adulthood. The important remaining question is which factors contribute to continuity, and which factors to discontinuity

Personality Continuity

Personality shows continuity when the environment remains stable. Thus, the way people select stable environments contributes to personality continuity (Roberts & Caspi, 2003). Further, personality shows continuity due to genetic factors. Analyses of cross-twin correlations suggest that 50–80% of stability is due to genetic factors (Lyons et al., 2009) and dramatically increases by middle childhood (Davis, Haworth, & Plomin, 2009). Two mechanisms by which genes might influence personality stability were proposed, either physiological mechanisms (e.g., individual differences in behavioral inhibition are heritable and stable and appear to be influenced in early childhood by genetic factors) or gene-environment interactions (personality continuity across the life course as result of transactional processes, that are – in part – genetically influenced). Finally, person-environment transactions contribute to personality continuity, that is, environment and existing (inherited) individual differences promote continuity (Roberts & Caspi, 2003).

Personality Discontinuity and Change

People respond to explicit and implicit contingencies and change their behavior by responding to reinforcers and punishers (Roberts & Caspi, 2003). Impressive examples for explicit contingencies stem from research on behavioral inhibition to analyze parental attempts to shape their childrens’ personality and biologically and genetically based temperament as a function of avoidance and approach behavior to novel situations (Kagan, 1994). In contrast, implicit contingencies are characterized as unspoken expectations and demands that shape a person’s behavior and personality by defining appropriate ways to behave within (newly) acquired roles or positions in society.

Caspi and Roberts (2001) proposed three additional mechanisms of how personality may change. Interestingly, all three may be considered social contextual mechanisms because they rely on existing social relationships. However, relationships in which these mechanisms occur are considered environmental influences on the individual development of personality, that is, watching ourselves (self-insight learning), watching others (social learning), and listening to others (learning from other’s description of oneself).

It is worth noting that most research on personality development is cross-sectional. Until today, there is no empirical evidence regarding possible long-term effects of self-congruent or self-incongruent feedback from significant others (e.g., from intimate partners). Repeated self-perception-incongruent feedback may contribute to personality change, especially, if the feedback comes from people whom we consider as knowing us well. Overall, an overarching theoretical approach is needed that focuses on the development of mechanisms contributing to both discontinuity and change in personality development, identity development, and identity structure and their embedment in social contexts.

Co-Development in Personality

People tend to marry partners who are similar to themselves (e.g., Robins, Caspi, & Moffitt, 2000). Less is known about how one partner’s personality development influences the personality development of the other partner. So far, only a few studies have investigated how changes or stability in personality of one intimate partner affect personality change or stability of the other partner. Caspi, Herbener, and Ozer (1992) showed that spouses become more similar over time. This finding suggests that similarity is an adaptive characteristic of long-term partnership quality. However, findings regarding the impact of personality similarity on partnership quality are equivocal (Neyer & Voigt, 2004). The heterogeneity in research findings suggests that effects may depend on additional factors. For example, similarity might be more closely related to some components of partnership quality (e.g., marital satisfaction) than to others (e.g., stability). Also, effects may vary, depending on the specific personality facet that is studied. If, for example both partners are high on dominance, effects on partnership quality might differ from those if both partners are high on extraversion. Partnership history of a couple may also play a role. Importantly, the specific life context is likely to be relevant. Personality evolves as a function of life experiences (Roberts, Caspi, & Moffitt, 2003). The same is true for marital satisfaction (Gorchoff, John, & Helson, 2008). These findings suggest that changes in life context (e.g., experiencing important life events) may provoke changes in personality and thus affect the co-evolution of the two partners’ personalities as well as partnership quality. Therefore the main questions regarding co-development are: How do partners’ personalities co-evolve across time and when the couple experiences a transition or an important life event? How do these changes affect partnership quality? How do they spill over into other life domains, that is, how do they affect well-being and behaviors at work? And, finally, are these processes different in young age, middle age, or old age? The five reviews of the special issue address these questions and summarize recent evidence how intimate partner co-develop in personality.

The first article by Allemand and Martin (2016) focuses methodologically and conceptually on correlated change in personality. It refers to the question of whether and to what degree changes in personality are interrelated over time within and between individuals. The authors propose a categorization framework with multiple dimensions and discuss theoretical concepts of correlated change that help understand the patterns, causes, and mechanisms underlying correlated change in personality. In a next step they describe several statistical approaches to modeling correlated change and summarize research on correlated change within the Big Five personality traits, and between the Big Five personality traits and three domains of life.

The second article by Wrzus and Neyer (2016) investigates changes in the co-development of personality characteristics and friendships across the life span. They address how personality traits shape friendship development (i.e., selection effects) and how friendships shape personality traits (i.e., socialization effects) and examine how selection and socialization effects change across the life span. The review of longitudinal research indicates that selection effects on friendships intensify during adolescence, peak in young adulthood, and diminish throughout middle and late adulthood. Socialization effects through friendships seem to be moderately sized during adolescence, then small to negligible from young adulthood onwards.

The third article by Erol and Orth (2016) reviews theoretical perspectives and available evidence on three questions, that is, the effect of people’s self-esteem on the quality of their romantic relationships, the effect of self-esteem similarity between partners on relationship quality, and the psychological mechanisms that account for the link between self-esteem and relationship quality. The evidence suggests that high self-esteem is beneficial in romantic relationships and that high self-esteem has a positive effect also on the partner’s relationship satisfaction. The authors suggest that perceived regard and secure attachment between the partners explain why self-esteem is beneficial in romantic relationships. As for Big Five traits, evidence for the degree of self-esteem similarity between partners does not influence couple’s relationship satisfaction.

The fourth article by Weidmann, Ledermann, and Grob (2016) presents dyadic research on the association between Big Five traits and both life and relationship satisfaction in couples focusing on self-reported personality, partner-perceived personality, and personality similarity. The findings indicate the importance of self-reported as well as partner-perceived personality – how the partner rates one’s own personality – for the satisfaction of both partners. Specifically, evidence suggests intrapersonal and interpersonal effects for neuroticism, agreeableness, and conscientiousness on life and relationship satisfaction. For the partner-perceived personality, intrapersonal and interpersonal effects were present for all Big Five traits. Again, partners’ similarity in personality traits is barely related with their satisfaction when controlling for partners’ personality.

Finally, the fifth article by Steiner and Krings (2016) reviews research on negative and positive crossover from work to family and from family to work in couples. Evidence mainly highlights indirect crossover based on spillover processes and marital interactions. More specifically, the review shows that incumbents’ positive and negative experiences at work cross over to their spouses’ well-being or family functioning through experiences of work–family enrichment and work–family conflict, respectively, and, for negative crossover, through negative marital interactions.