 11. Personality Development across the Life Course 269
ingly socially invested in romantic relation -
ships is associated with increases in emo -
tional stability and self-  esteem (e.g., Lehnart 
et al., 2010).
Two recent findings challenge the social 
investment principle or create the need to 
modify the principle. First, in the research 
on the psychological factors associated with 
social investment, investment in work was 
associated with personality trait change at 
all ages, not just in young adulthood (Hud -
son et al., 2012). Though only one study, 
the findings challenge the assumption that 
social investment is primarily a cause of per -
sonality trait change in young adulthood. It 
is possible that there is nothing special about 
social investment in young adulthood, and 
experiences related to work or relationships 
may lead to change across the lifespan. If 
this is true, researchers will need to deter -
mine whether the majority of factors asso -
ciated with the social investment principle 
occur during young adulthood.
Additionally, the lack of personality trait 
change associated with new parenthood 
(Specht et al., 2011; Van Scheppingen et al., 
2016), or the change occurring in the op -
posite direction than we would expect (Gal -
diolo & Roskam, 2014; Jokela, Kivimäki, 
Elovainio, & Keltikangas-  Järvinen, 2009), 
presents a challenge for the social invest -
ment principle. This does not mean that 
having children does not lead to psychologi -
cal changes, as research has found that tak -
ing on the role of parent is associated with 
identity change (Sengsavang, Pratt, Alisat, 
& Sadler, 2018). But becoming a parent, 
unlike other normative transitions, is not 
associated with the same changes in per -
sonality traits on which we based the social 
investment principle (i.e., increases in agree -
ableness, conscientiousness, or emotional 
stability). It may actually be related to even 
slightly negative changes (e.g., Galdiolo & 
Roskam, 2014).
We see two possible explanations for 
these findings. First, the expected changes 
(i.e., those associated with other normative 
transitions) may happen before a person be -
comes a parent. Individuals who plan to be -
come parents may increase in agreeableness, 
conscientiousness, and emotional stability 
prior to making the effort to conceive (Rob -
erts, O’Donnell, & Robins, 2004). Second, it is important both to define social invest -
ment correctly and to understand the causal 
mechanism behind the principle. Perhaps 
a person’s personality trait change occurs 
not because he or she acquired or made a 
commitment to a role, but because he or she 
feels a new sense of mastery derived from 
the successful fulfillment of that particular 
role. Given the almost random nature of a 
child’s personality and behavior in infancy 
(Loehlin, 2005) it is quite possible that a fair 
number of parents experience stress because 
of the intrinsic conflict that comes with han -
dling people who are unlike themselves and/
or handling children who are truly inconsis -
tent over time and situation. Future research 
should investigate further what aspects of 
the experience of taking on new roles are as -
sociated with normative changes in person -
ality traits in young adulthood. It may also 
be the case that parenting does not affect 
personality trait change as much as change 
in the other domains of personality, such as 
goals and narratives.
The Corresponsive  Principle
According to the corresponsive principle, 
people’s personality traits lead them to enter 
specific environments and have specific ex -
periences, and those environments and ex -
periences change the personality traits that 
led them to that particular situation. For 
example, people might choose a job in sales 
because of their high levels of extraversion, 
and the demands of being a salesperson 
may lead to increases in extraversion. The 
corresponsive principle describes a recipro -
cal relationship, similar to what the theory 
of self-  efficacy describes (Bandura, 1977). 
One thing to note is that the corresponsive 
principle is not stated in the extreme (i.e., 
that all person–  environment transactions 
occurring over the life course follow this re -
ciprocal pattern) (Wood & Harms, 2016). 
It came about because of recurring patterns 
in many longitudinal studies, but this pat -
tern was not found in all studies, or for all 
relationships.
The original studies that led to the de -
velopment of the corresponsive principle 
tended to test a large number of personal -
ity traits and life experiences simultane -
ously (e.g., Lüdtke et al., 2011; Roberts et 