The Psychology of Friendship - Oxford University Press (2016)

32 Friendship Across the Life Span

shown to predict decreases in extraversion and self- esteem (Sturaro, Denissen, van
Aken, & Asendorpf, 2008). Likewise, increases of friendship conflict and higher
levels of insecurity toward friends predicted increases in neuroticism across young
adulthood (Figure  2.2B, Mund & Neyer, 2014). Again, a comparison of effects
across different relationship categories corroborated the predominance of effects
for friendships, that is, relationships that reflect self- selected lifestyles and social
contexts (Mund & Neyer, 2014).
In sum, although earlier research raised doubts about friendships influencing
personality development (Asendorpf &Wilpers, 1998; Neyer & Lehnart, 2007),
recent studies evidenced such longitudinal transactions (for review see Wrzus &
Neyer, 2016). The interplay of personality traits and friendships provides a generic
example of a full transaction pattern (i.e., personality effects on relationships
and vice versa), which emphasizes the importance of friendships in the person–
environment interplay. However, the pattern of results is complex, as effects are
scattered across all trait domains. Further research is needed to gain deeper insight
into the specific contingencies between different personality traits and various rela-
tionship qualities. Furthermore, the processes that mediate mutual influences of
personality and relationship characteristics as well as potential moderators of their
interplay have yet to be examined. Research on effects of peer contagion suggested
that friendship effects might vary by relationship quality (Prinstein, 2007; Urberg,
Luo, Pilgrim, & Degirmencioglu, 2003).

Future Research Areas and Conclusions

The previous sections addressed characteristics and functions of friendships in
young and middle adulthood, how friendships differ within and between peo-
ple, how friendships change in general during young and middle adulthood, and
how people’s personality and friendships reciprocally affect each other over time.

(A) (B)

Personality eects on friendship change Friendship eects on personality change

Change in

closeness in

friendships

Extraversion

Neuroticism

Conscient-

iousness

Change in

insecurity in

friendships

Change in

neuroticism

Conict in

friendships

Insecurity in

friendships

Figure 2.2 Selected findings from Mund and Neyer (2014) of (A) personality effects on
friendship change and (B) friendship effects on personality change.