How Personality Traits Change Over Time with Wiebke Bleidorn, PhD


How do personality traits change and develop
over time? And to what extent do environmental, sociocultural,
and biological factors contribute to personality change? Hello, I’m Marla Bonner. Welcome to APA Journals Dialogue, a podcast
featuring research from early career psychologists published by the APA Journals program. Today’s episode features Dr. Wiebke Bleidorn,
Director of the Personality Change Lab at the University of California Davis, and a
2019 recipient of APA’s Award for Distinguished Scientific Early Career Contributions to Psychology. Her research has helped uncover the biological
and sociocultural mechanisms that underlie personality stability and change. As a recipient of an APA award, Dr. Bleidorn
was invited to submit a manuscript to the American Psychologist for consideration in
the journal’s annual awards issue. This awards issue, published in December 2019,
featured an article by Dr. Bleidorn and her colleagues. The papers in the issue reflect the highly
relevant, innovative work that’s being conducted in the field of psychology today. We are so pleased to have you, Dr. Bleidorn. Thank you for taking the time to join us today. We appreciate it. Thank you so much. It’s a pleasure to be here. Thank you. Can you share a quick summary of your work
with our listeners? As you already said, I’m a personality psychologist,
and so I’m interested in individual differences in personality traits and particularly in
personality change. In my work, I study when people change in
their broader personality traits, how they change in their broader personality traits,
and, ideally, we are also trying to get answers as to why personality traits change. Let me give you an example. I am interested in, for example, people’s
self-esteem. People’s global self-esteem describes how
much they accept and like themselves. And that is, on average, pretty stable, but
people tend to change in their self-esteem and they do so systematically across the life
span. An interesting finding of the past 20 years
that has been replicated many times is that most people tend to increase in their self-esteem
after adolescence. Adolescence is a time when most people experience
a little dip in their self-esteem. Maybe you can relate to that. We also found that these changes seem to be
related to both genetic and environmental influences, and so we are now at the point
in our research where we are trying to find out—What is it in the environment that can
drive changes in people’s self-esteem? Can we identify certain life experiences or
certain environmental contexts that shape our self-esteem? Self-esteem is really just one trait that
I happen to have studied quite a bit over the past couple of years. Another question that we have is—What is
the process? How do changes in self-esteem unfold? What inspired you to pursue research in personality
development? It sounds like you’re going beyond that basic
“nature vs. nurture” argument that has been around for some time in the field of
psychology. I think there are probably historical reasons
and also personal reasons for why I ended up studying this topic. Historically, if I can go back a little bit,
the field of personality psychology has seen some pretty dramatic paradigm shifts over
the past hundred years or so. An interesting historical marker was the publication
of Walter Michelle’s book Personality Assessment in 1968, in which he claimed that personality
traits don’t exist or don’t matter because our behavior is too variable across situations
to call anything a stable trait. With this claim out there, our field, personality
psychology, has really put a lot of effort, work, and attention to the stability of personality
traits. So many people have tried to show and have
successfully shown over and over again that personality traits are relatively stable,
heritable, and also predictive of important life outcomes such as health, income, and
relationship success. Between the 1970s and the early 2000s, I would
say, a lot of research was focused on traits as stable entities. While this was important at the time, it also
became clear that we were probably overshooting a little bit because what really happened
is that lay people and scholars alike thought, “Well, personality traits are so stable,
they cannot change at all.” In fact, publications have come out that said
that once people reach age 30, their personality is basically set like plaster, and that there’s
very little we can do to change people’s personality. A couple of publications in the early 2000s,
especially those spearheaded by Brian Roberts, have shown that that is not true. Two seminal meta-analyses have shown that
personality traits are relatively stable, but they also change, and they do so actually
across the lifespan, meaning that there is no upper boundary. In fact, people aged 70 and older can still
undergo pretty remarkable changes in their personality traits. The publications came out when I was in grad
school, and obviously I was fascinated by these ideas. I’m trained as a behavioral geneticist, so
my focus was very much on not only the genetic, but also the environmental influences on individual
differences in personality. What could be more interesting to see than
a certain environment leading to a change in a trait? I was fascinated by that idea and since then,
I have tried to identify factors in the environment that we can pin down and measure, that might
lead to changes in personality traits. That certainly sounds like some fascinating
work, and you are completely motivated and inspired by it. But what challenges have you encountered over
the course of your research? Aside from the challenges that most researchers
encounter—like experiencing rejections—there are some challenges more specific to my area
work that have become more obvious over the past couple of years because the field, like
I said, has seen a major paradigm shift since the early 2000s. There has been now 20 years of research on
personality change, so I would say we have made great progress in showing that personality
traits can change, and that some of these changes seem to be related to certain environmental
influences, even purposeful interventions. But as it looks right now—in order to make
the next transformative step and learn about specific sources in the environment that can
change personality traits, we probably need to change our standard research practices. The reason is that we are dealing with small
effects, like most social scientists do, but we probably also had a bit of a simplified
idea about how environmental factors—let’s say life experiences—might work. What do we need in order to make real progress? The biggest challenge right now is that we
need very large samples. Maybe I can give you another example involving
self-esteem. A hypothesis that people have is that major
life events, such as divorce, might impact people’s self-esteem. If you really want to study the implications
of divorce, you would need to start out with a very large group of participants who are
in a romantic relationship in the beginning of the study—that is already one constraint—and
ideally haven’t experienced a divorce yet because you would like to know what happens
before and after the divorce. You will need to follow these people over
a long period of time—and I don’t want to say you have to hope some of them get divorced,
but you have to wait it out and count on the fact that people get divorced. We recently did such a study where we started
out with 13,000 participants and ended up with 400 divorcees over a period of 10 years
in a nationally representative study. This is a major sample and, ideally, we also
want to compare these participants with a comparison group because one person who experienced
divorce is probably not exactly like every other divorcee. We cannot use a randomized experiment here
and say, “Well, you got the worst. You don’t,” so we just have to wait it out
and create comparable comparison groups. We have to follow the trajectories of these
two comparison groups over a long time period in order to be able to compare them. So, you can see that in order to come up with
a reasonable sample size, you have to start out very large, and this is a major challenge
that we have right now. We are running into these paradoxical problems
where we sometimes have large sample sizes, but very few assessments of personality because
traditionally, the idea was that personality traits are stable. Many studies only assess personality once,
assuming that it doesn’t change, whereas we want to know: Well, does it change? So, we need large samples and multiple assessments
of personality. We also know very little about the timing
or the timescale at which changes unfold. Ideally, we want a high number of assessments,
and we want the assessments to be frequent. So, all of that increases costs. In a perfect world, we would love not only
to have self-reports, but also to have other methods of reports—informant reports or—even
better—reports that don’t require any human reporting at all, but rather rely on mobile
sensing, digital footprints from social media, or perhaps biomarkers. In a super ideal world, we also want these
samples to be not only WEIRD samples. WEIRD samples are samples that are Western,
educated, from industrialized and rich democratic countries. These are the samples that we usually use,
but in order to really learn something about human nature, we also need samples from other
cultures. In my perfect study, I would need massive
resources, but also expertise that I don’t have and knowledge that clearly requires collaboration—researchers
with different expertise who bring resources and knowledge to the table to really make
progress in this area. So, the challenge right now is: How can we
establish a collaborative approach to this problem and try to get funding for studies
that are really making progress in this area? Let’s say you overcome these challenges and
you complete your dream study. What is the end goal of the research and,
even more important, what is the benefit for humankind? That’s what my paper is about. When you go to a bookstore right now, and
you go to the self-help section, none of that stuff is evidence-based because we are still
trying to figure out how to improve your self-control and how to improve your self-esteem, so none
of these “12-step programs” really work. We are trying to find out what it is that
really makes people change because right now, we don’t know about the process. We should be at the table when it come not
only to self-help literature, but also policy implications—what kids learn in school,
for example. The idea is always, “We should improve their
self-esteem or self-control,” but we don’t know how. That will be the end outcome. What’s particularly notable about your work
in personality change is that it represents an emerging sub-field of psychology and specifically,
the intersection of personality, developmental, and social psychology. Have you collaborated with professionals in
other areas of psychology to advance research in the subfield? Yes, and in fact, my first faculty job in
the Netherlands was in developmental psychology, and my focus there was on lifespan development,
so I had the opportunity to work with developmental psychologists there. In grad school as a behavioral geneticist,
there were psychologists and also social scientists from other areas, and I had the opportunity
to learn from and collaborate with researchers from these areas, which I find very rewarding. A challenge sometimes can be language, terminology,
and a bit of a vocabulary that has to be learned in order to function well but once these difficulties
are overcome, I found that different perspectives are helpful when it
comes to questions that go beyond our typical bread-and-butter study. In fact, in my current work, I’m trying to
reach out to researchers in other fields, particularly computer scientists in health
and communications research in order to develop new approaches to assess personality that
go beyond a typical self-report measures. For example, we are trying to connect to people
who can help us with collecting digital footprints and online data. We are also trying to find people who can
help us use biological markers and smartphones, for example, to help develop new assessment
technologies and validate those to assess personality in a way that goes beyond our
traditional questionnaires. As we close out today’s wonderful dialogue—and
again, thank you for taking the time to talk with us today—particularly for the benefit
of our early career psychologists and graduate student listening audience: Can you just share
a little bit about what you have learned about navigating the publishing field? Is there any particular advice that you would
wish to share with that audience about publishing in psychology? Well, I think I’ve learned that a clear message
and a good idea can go a long way. We have many ideas and we sometimes try to
pursue many ideas in one publication, but I think it’s really a good idea to just focus
on one idea and hammer that home instead of trying to do too many things at once. I guess you could describe this principle
as addition by subtraction. That’s what I tell my grad students, at
least. I think it’s really helpful to have a message
and be very clear about it. Another thing that I’ve learned is that Willie
Nelson was probably right when he said that good songs come easy. When you think, “Well, that theoretical
framework is tight; it makes sense and it feels good. All the indicators suggest that it’s doable
and the research design feels right,” then it’s a good idea. If, in the beginning, you’re already struggling
to make a strong case for your idea, maybe it’s worthwhile to put that away until it
feels more easy and more natural. That advice is maybe not as “cookbook recipe”
as one would hope, but I find that the publishing experience is also not as straightforward
as you might think. So, maybe I’ll leave it at that. Well, I think that is solid advice. Sometimes it’s better to just keep it simple. With that, I want to say thank you so much
for taking the time, for speaking with us today and sharing a bit about your experience
as an early career social psychologist. We really appreciate it and we wish you continued
success. Thank you. It was a pleasure
To find out more about American Psychologist and read articles from the December issue,
please click the link in our episode notes. Before we go, we want to remind you that we
want to hear from you. Email your feedback to [email protected]
and please consider giving us a rating on iTunes—it really does help!
APA Journals Dialogue is part of the APA podcast network, which includes other informative
podcasts like Speaking of Psychology, which highlights some of the latest psychological
research, and Progress Notes, a podcast focused on the practice of psychology. You can find all of our podcasts on iTunes,
Stitcher, Spotify or wherever you get your podcasts. I’m Marla Bonner with the American Psychological
Association. Thank you for listening.

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