330 III. DEvELOPMENT
can be a result of direct social “press” from 
the outside environment (e.g., in school, 
teachers enforce students’ silence during lec -
tures). However, the adoption of goals might 
also be more indirect, for example, when in -
dividuals gradually internalize social roles 
related to a life transition (e.g., how to be 
a good parent). This might even happen 
before a life transition has occurred, in the 
sense of anticipatory goal setting (Roberts, 
O’Donnell, & Robins, 2004).
A second precondition outlined by Hen -
necke et al. (2014) is that the new behaviors, 
thoughts, and feelings associated with per -
sonality change are feasible. This feasibil -
ity has both an objective (a behavior that is 
impossible will not occur) and a subjective (a 
behavior that is deemed too difficult by the 
individual will be unlikely to occur) compo -
nent. Adjustment to a new role can require a 
complex set of new behavioral, affective, and 
cognitive responses, some of which might 
be more feasible than others. For example, 
when entering the job market, an individual 
needs to learn to get up on time, take care 
of the proper business attire, navigate social 
interactions with colleagues and supervisors, 
keep track of relevant professional develop -
ments, and so forth. In addition, there might 
be industry-  specific expectations (e.g., acting 
very friendly is expected of waiters but not of 
bouncers) (Denissen, Ulferts, Lüdtke, Muck, 
& Gerstorf, 2014). Individuals might differ 
in their ability to perform these different be -
haviors in response to a major life transition.
A third precondition of Hennecke et al. 
(2014) is that cognitive, affective, and be -
havioral changes need to become habitual 
to become part of personality. Such habitu -
ation processes can occur as an automatiza -
tion of correlated behaviors that are related 
to one particular goal or expectation. For 
example, when entering the job market, an 
individual could try to meet the goal of “act -
ing in a professional manner” by interacting 
politely, courteously, and confidently with 
customers. Over time, the behaviors neces -
sary to implement this goal will become in -
creasingly effortless and no longer require a 
conscious level of goal access. In such a situ -
ation, merely entering the building in which 
one works might be sufficient to trigger the 
once-  conscious goal and its associated be -
haviors (cf. Custers & Aarts, 2010).Mediators of  Personality  Change
Modern theories of personality develop -
ment have emphasized the role of momen -
tary behavioral, cognitive, and affective 
changes as mediators of personality trait 
change (Geukes et al., 2018). For example, 
sociogenomic personality theory (Roberts 
& Jackson, 2008) proposes that continuous 
changes in individuals’ affective, cognitive, 
and behavioral states can translate into sub -
sequent personality trait changes. In a some -
what similar vein, Fleeson (2001) has argued 
that personality traits are density distribu -
tions of states, and that the frequent display 
of event-  correlated behaviors (e.g., caring 
for one’s children) might over time become 
perceived as trait relevant (e.g., a caring per -
son). Wrzus and Roberts (2017) have pro -
posed a general framework of personality 
trait change that attributes long-term per -
sonality development to repeated short-term 
sequences of triggering situations, expectan -
cies, states, and reactions through associa -
tive and reflective processes.
To better understand how behavioral, 
cognitive, and affective short-term processes 
are linked to long-term changes in personal -
ity traits, longitudinal designs including fre -
quent assessments of states and traits would 
be needed that assess personality traits lon -
gitudinally as well as the relevant short-term 
processes repeatedly during the experience 
of major life transitions (Geukes et al., 2018). 
To illustrate, in a longitudinal study on self- 
esteem development during an academic 
exchange year, Hutteman, Nestler, Wagner, 
Egloff, and Back (2015) attempted such a 
design to examine the impact of short-term 
state changes on long-term trait changes in a 
sample of German university students. They 
found that increases in state self-  esteem dur -
ing an academic exchange year predicted 
differential changes in trait self-  esteem over 
1 year and that the experience of greater so -
cial inclusion prospectively predicted higher 
state self-  esteem and vice versa. Presumably, 
social inclusion and social activities during 
the academic exchange year triggered chang -
es in state self-  esteem, which in turn led to 
changes in individuals’ trait self-  esteem. 
Similar research designs are needed to gain 
more knowledge about the short-terms pro -
cesses during major life transitions and their 