266 III. DEvELOPMENT
in the absence of intervention research, it is 
challenging to draw causal conclusions from 
this research. Nonetheless, the sheer number 
of studies, their consistency, and their scope 
support an inference that personality trait 
change is unlikely to be caused only by pre -
programmed genetic factors (e.g., McCrae & 
Costa, 2008) and is most likely the result of 
a variety of different experiences, both ob -
jective and subjective. This conclusion leads 
to our next question: If personality traits do 
change and appear to change because of ex -
perience, is it possible to intervene to change 
traits if one is so motivated?
Can Personality Traits Be  Changed?
With the accumulation of consistent and ro -
bust evidence that personality traits can and 
do change, the natural question becomes 
whether they can be changed through an 
active intervention. This idea has not been 
widely entertained in developmental or per -
sonality research until recently, a possible 
result of the continued debate over whether 
personality traits exist, and whether they are 
or are not stable enough across time and sit -
uation (Roberts, 2009). Also, some have hy -
pothesized that the change identified in per -
sonality traits is entirely the result of genetic 
factors (McCrae & Costa, 2008), but this 
hypothesis has not been borne out in geneti -
cally informed research (Bleidorn,  Kandler, 
Riemann, Angleitner, & Spinath, 2009; Luo 
et al., 2017).
Despite the prevailing lack of attention 
focusing on whether personality traits can 
be changed, there have been a few studies 
that demonstrated the possibility. For ex -
ample, Piedmont (2001) reported that treat -
ments to improve vocational skills, coping 
abilities, and spiritual development are as -
sociated with changes in the Big Five. More 
recently, a cognitive intervention was associ -
ated with changes in openness to experience 
in old age (Jackson, Hill, Payne, Roberts, & 
Stine-  Morrow, 2012), but this finding failed 
to replicate in similar interventions (Sander, 
Schmiedek, Brose, Wagner, & Specht, 2017). 
From the viewpoint of personality psychol -
ogy, there have been a few, though provoca -
tive, studies supporting the argument that 
personality traits can be changed.
While there is only a small literature in 
personality psychology, there has been a long-  standing literature within clinical psy -
chology on personality trait change result -
ing from typical clinical interventions (e.g., 
Bagby, Joffe, Parker, Kalemba, & Harkness, 
1995; Borkovec et al., 1987). More recent -
ly, clinical researchers have focused on and 
called for interventions that change person -
ality traits (e.g., Barlow, Sauer-  Zavala, Carl, 
Bullis, & Ellard, 2014; Magidson, Roberts, 
Collado-  Rodriguez, & Lejuez, 2014; Quilty 
et al., 2008; Soskin, Carl, Alpert, & Fava, 
2012). This perspective was generated from 
the insight that not only are clinical inter -
ventions potentially efficacious for chang -
ing personality traits, but also personality 
trait change may be the mechanism through 
which therapy is effective. For example, a 
double-  blind placebo control trial showed 
that taking an antidepressant resulted in 
both improvement in depression and in -
creases in emotional stability (Tang et al., 
2009). Most importantly, the changes in 
emotional stability mediated the effect of 
antidepressants on depression and long-term 
relapse, indicating that long-term effective -
ness of therapy may result through changes 
in personality traits.
Upon further examination, we recently 
found that there is a rather large amount 
of research in clinical psychology that ex -
amined (if not explicitly, then indirectly) 
whether personality traits change as a re -
sult of therapy. Many clinical researchers 
include personality trait measures in their 
evaluation of various forms of therapy, 
seemingly to be thorough; while a symp -
tom measure of anxiety may have been the 
primary outcome measure of interest, these 
researchers also included measures of trait 
anxiety, for example. Once we discovered 
that clinical psychologists have a habit of 
including trait measures in their evaluation 
research, we found over 200 clinical stud -
ies reporting changes in personality that 
resulted from therapy. In a meta-  analytic 
review, we found that going through any 
form of psychotherapy resulted in marked 
increases in emotional stability (Roberts, 
Luo, Briley, Chow, Su, & Hill, 2017). These 
changes in emotional stability were con -
firmed in a subset of experimental studies, 
as well as a small set of studies that tested 
interventions with nonclinical samples or 
for nonclinical issues. Most importantly, 
a relatively large subset of studies tracked 