312 III. DEvELOPMENT
observed complication model effects, with 
changes in externalizing problems affecting 
scores on benevolence, conscientiousness, 
and imagination, whereas changes in inter -
nalizing problems were positively related to 
changes in imagination, conscientiousness, 
and negatively related to changes in emo -
tional stability.
The dimensional perspective on psycho -
pathology further expedited the search for 
the developmental antecedents of personal -
ity disorders. This domain was almost en -
tirely ignored in DSM-IV (De Fruyt & De 
Clercq, 2014). Except for antisocial person -
ality disorder, personality disorders were 
only considered from the age of 18, because 
personality was assumed to be still under 
construction before reaching adulthood. 
Moreover, assessment psychologists wanted 
to be cautious and avoided using diagnos -
tic labels with a strong negative connotation 
for young people. Early indicators and di -
mensions useful for the description of per -
sonality pathology, however, turned out to 
be already present before young adulthood 
(Cohen, Crawford, Johnson, & Kasen, 2005; 
De Clercq, De Fruyt, Van Leeuwen, & Mer -
vielde, 2006; De Fruyt & De Clercq, 2014), 
opening a challenging research agenda for 
clinical psychologists to look for develop -
mental antecedents of personality pathology 
in childhood and adolescence. Research by 
De Clercq, Hofmans, Vergauwe, De Fruyt, 
and Sharp (2017) used such an early-trait 
indicator approach in a five-wave, multi- 
informant investigation spanning 10 years 
of childhood, adolescence, and emerging 
adulthood to describe the dark triad traits 
of narcissism, Machiavellianism, and psy -
chopathy.
Relationship  Level
Personality was also studied in relation to 
the development of personal relationships, 
especially how adolescents build and main -
tain interpersonal relationships and net -
works with friends and peers. Traits such as 
shyness and traits from the interpersonal cir -
cumplex and the FFM have been studied in 
conjunction with phenomena such as loneli -
ness. Vanhalst, Goossens, Luyckx, Scholte, 
and Engels (2013), for example, described 
five different trajectory classes in the devel -opment of loneliness from mid- to late ado -
lescence ( N = 389), showing that three of the 
FFM dimensions assessed at age 15 helped 
to differentiate trajectories. Adolescents in 
the stable low-  trajectory class were char -
acterized by the highest levels of extraver -
sion, agreeableness, and emotional stability. 
Those with chronically high levels of lone -
liness reported the lowest levels of agree -
ableness, and adolescents in the moderate 
decreasing-  trajectory class scored lowest on 
extraversion and emotional stability.
Neal, Durbin, Gornik, and Lo (2017) ex -
amined in detail and through observational 
measures how the temperament traits of 
positive emotionality, negative emotionality, 
and effortful control of preschoolers are af -
fected by their social interactions and peer 
play relationships across an entire school 
year. Besides rank-order stability for obser -
vations across the year, the research showed 
how children’s traits affected their play rela -
tionships, with those exhibiting high levels 
of negative affectivity showing a decreased 
likelihood of building play relationships. 
Participants’ positive affectivity and effort -
ful control levels converged towards those 
they frequently interacted with across the 
year. No such codevelopment effects were 
observed in a Dutch study of adolescents 
transitioning into young adulthood by Bor -
ghuis and colleagues (2017). They analyzed 
seven-wave longitudinal data obtained on a 
sample ( N = 2,230) from ages 12 to 22, and 
found no dyadic codevelopment effects with 
friends and siblings, which suggests that de -
velopmental personality processes tend to 
change independently of contacts with peers 
during adolescence, and that shared experi -
ences do not necessarily have the same ef -
fects on friends and sibling personalities.
One specific type of interpersonal rela -
tionship is how adolescents interact with 
their parents and vice versa. How children 
and adolescents’ (from ages 5 to 15 years) 
personality traits interact with parenting 
behavior and associates with internalizing 
and externalizing behaviors was extensively 
examined by Van Leeuwen et al. (Van Leeu -
wen, Mervielde, Braet, & Bosmans, 2004; 
Van Leeuwen, Mervielde, De Clercq, & De 
Fruyt, 2007) and how these associations de -
velop over time by Prinzie and colleagues (de 
Haan, Dekovi ć, Van den Akker, Stoltz, & 