 11. Personality Development across the Life Course 273
lieve they will thrive (Nye & Roberts, 2019). 
Carol is attracted to the college environment 
to achieve her goals and because she sees 
her personality fitting with that experience 
and the rewards that it will bring, such as 
a white-  collar, professional occupation. Se -
lection  refers to people being selected into 
environments because of their personality 
(Roberts, 2006). Tom is being recruited by a 
college despite not having a strong desire to 
go to college. Let’s assume that the coach is 
recruiting Tom because he likes Tom’s per -
sonality and how it will fit with his team and 
their team climate. Presumably, going into 
an environment that one is both attracted to 
and selected for because of one’s personality 
should result in increased continuity (via the 
niche-  picking principle) because these en -
vironments will support Carol’s and Tom’s 
existing personality qualities.
The reason why individuals like Carol and 
Tom are attracted to specific life paths and 
environments is that they perceive the quali -
ties of those environments as fitting with 
their personality. Recently, we proposed the 
TESSERA model to help identify the more 
concrete mechanisms that help translate 
person–  environment transactions into per -
sonality continuity and change (Wrzus & 
Roberts, 2017). In the TESSERA model en -
vironments come with Triggering situations 
and Expectations for certain behaviors. 
These expectations can be from others in 
the situation or are generated by a person’s 
interpretation of what the situation requires. 
These triggers and expectations elicit States 
(concrete thoughts, feelings, and behaviors). 
If the States are consistent with existing per -
sonality structure, Expressions are evoked. 
If the states elicited are contradictory to a 
person’s personality and are maintained for 
a long enough period of time, then personal -
ity change may occur. Finally, people ReAct 
to their experiences and changes in states, 
and through that reflection react to the situ -
ation (e.g., leave the situation), accommo -
date to the demands of the situation (e.g., 
change), and reconcile these changes into 
their identity. Repetitive sequences of situ -
ations, expectations, triggers, and reflection 
drive continuity and change in personality 
results. For Carol and Tom, it is the per -
ceived triggering situations and their per -
ceived expectations for these new environ -ments that would motivate them to want to 
enter specific schools.
Of course, life does not always go as 
planned. For the sake of argument, let’s con -
template what would happen if Carol’s life 
takes an unexpected turn: in her senior year, 
Carol becomes pregnant and decides to keep 
the baby without marrying the father. Here 
we have a completely new set of unexpect -
ed situations—  though quite possibly Carol 
might have at least begun to think of those 
options which by themselves might influence 
some preparatory personality change (Rob -
erts et al., 2004). This unexpected transition 
to parenting would be a robust triggering 
situation with an unforeseen set of expecta -
tions, many coming from other parties, such 
as her family and friends. When confront -
ed with the reality of parenting a newborn 
child and the changes in states that it neces -
sitates, Carol defers her entry to college and 
focuses on raising the baby with the help of 
her family. Given the demands of parent -
ing and the collective expectations for in -
creased responsibility for another life, Carol 
is forced to do and feel unexpected things. 
Rather than thinking of her own progress 
toward achievement goals, Carol must now 
understand and comply with expectations of 
nurturing and raising her child, and subor -
dinating her goals to the needs of another. 
These unexpected triggering situations and 
expectations would presumably bring with 
them changes in states that, if triggered con -
sistently over a long enough period of time, 
might result in at least temporary personal -
ity change (Roberts, 2018). These changes 
are captured in the person–  environment 
transaction of transformation (Roberts, 
2006).
Similarly, Tom did not consider college 
seriously, and when selected for a college op -
tion, let’s assume he was not prepared for 
the experience. Unlike his relaxed life in 
high school, in college he is forced to han -
dle the demands of higher expectations for 
studying and combining these challenges 
with the difficulty of working for a sports 
team in which many hours are dedicated 
to practice. One could see within a year of 
making the transition that Tom would con -
front persistent triggering situations calling 
for increased conscientiousness and emo -
tional stability and thus a transformation 