Episode 3: Personality Structure and Change

Emorie D Beck

Northwestern University Feinberg School of Medicine

A podcast episode presented for the European Association of Personality’s Personality Science Podcast.

Email: [email protected]

Twitter: @EmorieBeck

Emorie Beck was supported by National Institute on Aging Grants 5R01AG067622-02 and

5R01AG018436-20. Introduction:

Hi, I’m Emorie Beck. Thanks for tuning into the Podcast. I’m here today to talk about a few of the issues that are core to the study of personality psychology, particularly so-called personality structure as well as personality change. In my own research, I investigate personality structure and change using a variety of methods and at what I typically refer to as different levels of aggregation. Before I start, I want to note that what follows is necessarily not an exhaustive summary. I have a limited time span during which to cover a lot of information, which necessitates that I do, to some degree, pick and choose.

What is Personality?

But before we can talk about or define personality structure or change, I want to start with a seemingly simpler question – what is personality?

I remember when I was an undergraduate and taking a course called Personality and Clinical Assessment, the professor who taught the course, Jack Wright, started by asking the class “what is personality?” He then took our responses and turned them into a word cloud to try to uncover some of the common phrases and themes of our definitions. Many of these included the usual suspects like “dispositions,”, “tendencies,” “patterns,” and “characteristic” as well as the word that likely looms larger than any other in personality psychology: traits.

At that point, rather than telling us what personality was, which we all certainly wanted Jack to do, he split us into groups to create a personality questionnaire that we thought captured what personality was. The resulting inventories varied in length, content, the measurements, and virtually every other feature you can think of. By psychometric standards, none of these were good inventories. Really, they were quite bad.

But they taught us two lessons. The simplest was just that creating a measurement tool for personality is really hard. The second was more complicated and cut back to the question of what personality is. And that is that “personality is what personality tests test.” I’ll give you a moment to let the circularity of that sink in.

You see, we’d all been taught that personality was something measured in surveys and quantitatively ranked as being “high” or “low” on various dimensions. And given the chance to define personality however we wanted, we went on to do just that. But were we actually capturing personality? Not really, and it’s my opinion that this is exactly what Jack wanted us to learn in that exercise.

Personality is hard to define, and even harder to measure because the fundamental question is perhaps less “what is personality?” and more “how do you understand and define a person?” As someone who’s always loved history, to answer this question, we’ll take a brief trip through history, going a bit deeper into some history that was alluded in previous episodes, reviewing what past researchers and theoreticians have written on the topic. As we do, it will become clear, if it hasn’t already, that there is no one definition of personality, so I encourage you to do what Jack encouraged the class to do many times nearly a decade ago: “enjoy the struggle.” A Brief History of Personality

Personality psychology as a formal subdiscipline of psychology has been around for about 100 years. But the origins of it go much deeper, finding roots in philosophy, with, for example, Aristotelian virtues standing as an early example of thinking about the key characteristics of a person who is morally good. For the sake of time, however, I am going to focus on the past 100 years of thinking and research on personality, beginning with , who many consider to be one of the Fathers of personality psychology.

Allport

In 1921, while Allport was still completing his graduate training, he published a paper called “Personality and Character” in which he culled through a large number of contemporary definitions in an attempt to better understand and define personality. In this and later work, Allport was particularly focused on personality traits and their composition and classification.

In 1936, Allport and his colleague Henry Odbert published a paper titled “Trait names: A Psycholexical approach” in which they promulgated a lexical hypothesis for identifying and classifying personality traits. Essentially, proceeding from the observation that personality traits are observable characteristics that are often expressed as adjectives, personality traits could be better studied by looking at the natural language that is used to describe people. To that end, they pulled some 17,000 adjectives from the dictionary and set about classifying them using inductive means. In other words, they provided a structure of individual differences, a personality structure.

The legacy of the lexical hypothesis cannot be overstated. It seemingly united psychologists behind traits as the unit of personality. To many, personality became synonymous with such traits. Indeed, it’s much the reason that terms like personality structure remain pervasive to this day. However, in reality it opened as many questions as it answered. Although the classification system that Allport and Odbert offered had great merit, the painstaking effort required to cull such a large set of adjectives into meaningful clusters was egregious and left the possibility that some clusters may not reflect psychological reality. Thus, a critical question became how to reduce the larger set of traits into hierarchical clusters.

Cattell

At the same time, new statistical techniques were emerging in parallel that continue to shape both personality specifically and psychology more broadly. Most critically was the data reduction technique called , which was pioneered within psychology by Raymond B Cattell. Stated simply, this method seeks to define the structure of data by detecting correlational patterns in the way that people rated themselves on different adjectives. By identifying strong correlational patterns, characteristics that are similar can then be grouped into so-called latent factors. Thus, rather than having a huge list of unique traits, researchers could focus on a smaller set of clustered traits subsumed under a larger label. Data reduction techniques opened a new world of questions and opportunities as personality researchers set out to identify the latent personality traits in the hopes of identifying a set of universal traits, or dimensions of individual differences, on which people vary. In other words, to identify the structure of personality. Or, more aptly, of personality traits.

However, as powerful and important as data reduction techniques, the lexical hypothesis, the rise of traits as the unit of personality, and growing interest in personality structure were, to many they did not answer the question of what personality actually is. Or at the very least, they only answered part of the question. As personality grew as a field, it became clear that there were two goals that were being pursued in the service of understanding personality. On the one hand, there was the growing body of work attempting to identify the structure of personality traits in a population, or so-called between person differences, which are often subsumed under the label of nomothetic approaches. Such dimensional traits described differences across people, rank- ordering individuals on them. On the other hand, personality psychologists aimed to understand a single person, including how and why their experiences unfolded as they did, or so called idiographic approaches.

Gordon Allport himself was a proponent of the importance of both approaches. Indeed, just a year after he and Odbert published the lexical hypothesis, Allport published his seminal book “Personality: A Psychological Interpretation.” In some 500 pages, Allport exhaustively reviewed the literature and argued for the power of personality. In so doing, he struggled with three broad classes of questions about personality. First, descriptive questions in which the goal is, for example, to observe and document individual differences in a population or individual or patterns of change. Second, predictive questions wherein personality is tested as a precursor of some behavior or outcome. And third, explanatory questions that address the causal underpinnings of personality.

Indeed, in his definition of personality in his book, Allport touched on each of these questions. He wrote “Personality is the dynamic organization within the individual of those psychophysical systems that determine his [sic] adjustments to his [sic] environment.” His definition fundamentally roots personality as the property of an individual, their unique makeup, and their interactions with their environment. Moreover, although much of Allport’s book addresses the issue of traits, it makes no appearance in his definition. To him traits were tools through which to understand the dynamic organization that characterizes an individual, which in and of itself is a structure of personality – just that of a person. Or as Dan Cervone refers to these idiographic structures to reduce the jingle-jangle of terms, personality architecture.

From this view, then, we start to see that personality as we practically apply it exists at different levels. On the one hand, there is the unique configuration of characteristics and psychophysical systems of a single individual. On the other, the unique, nuanced persons can be summarized on a set of common traits that differentiate them from other people. Moreover, descriptive, predictive, and explanatory questions can be asked – and in some cases answered – at each of these levels.

Considered this way, then, Allport’s lexical hypothesis didn’t just define a method for understanding individual differences in a population. It also defined an approach for understanding an individual’s unique configuration personality traits. He reasoned that the lexical hypothesis extended to individual-level traits as well, and one could turn to the some 17,000 available trait names to characterize personality at the level of the individual.

For example, in one study Allport recruited 39 judges to both read a series of 172 published “Letters from Jenny and provide the trait adjectives that best described her. The judges provided adjectives that fell into roughly eight clusters that he called “common-sense traits.” However, he also coded the letters for tag words, whose frequencies were subjected to factor analysis with their resulting reduced clusters termed “factorial traits.” Although the results of methods largely converged, each method also produced unique traits that made up the structure of Jenny’s personality.

Allport’s study of Jenny’s letters stands largely alone in terms of quantitative studies of idiographic personality in the early to middle part of the 20th century. In part, this is largely due to the difficulty of acquiring the depth of information necessary for such idiographic, intensive investigations, such as those revealed in Jenny’s letters. As a result, studies of which personality traits defined the core dimensions of personality within and across populations largely dominated personality psychology at the time.

Variability and the Person-Situation Debate

Indeed, one feature of Jenny’s letters that is critical to note is that they spanned 12 years. So rather than having participants respond to an adjective checklist or formal personality survey at one point in time about tendencies in their behavior and experiences, the study of Jenny’s personality unfold over time, rather than simply being observed at a single point in time. As such, her behavior and experiences varied over time.

At the same time that Allport was building his theory of personality, attempting to understand both unique, idiographic traits, and shared, common, population level traits, a number of scholars were actively engaged with the question of variability. Individuals’ experiences and behaviors vary over time and across situations. Although these behaviors and experiences over time could be aggregated to represent tendencies, it threw away information about how those behaviors and experiences unfolded. Moreover, in their observation, measures of personality traits were not as predictive of actual behaviors and experiences as would be expected from trait theories.

For example, in the 1920s, Hartshorne and May embarked on a series of studies in which they investigated both temporal stability – or behaviors repeated in a context – and cross-situational consistency – or behaviors repeated across contexts – in behavior. In a population of elementary school students, they tested cheating behaviors across time and situations. Within a given context (e.g., an athletic test, spelling test), temporal consistency was quite high, with correlations ranging between .6 and .8. However, across contexts, cross-situational consistency was low, with correlations ranging between .1 and .3.

It’s at this point that we start seeing the complexity of personality unfold. So, let’s check to make sure we’re keeping track of all the parts – specifically the who, what, when, and where. On the one hand, we have people, perhaps lots of them, who are the “who” differ from one another. Then, we have the dimensions on which they differ and the experiences and behaviors they report, which are the what. Next we have, time, or the when, as behaviors and experiences occur and unfold over time. Finally, we have the where, or the contexts or situations that individuals find themselves in and in which individuals’ experiences are unfolding.

It’s in this landscape that the study of personality reaches a seeming reckoning point. In 1968, Walter Mischel published his book Personality and Assessment. In his book, Mischel argued for the importance of situations in understanding and predicting human behavior, highlighting the variability in behavior across situations that we were just considering. A central component of his argument stemmed from what he called the “personality coefficient” of .3, or the limit of the relationship between personality traits and behavior, which we saw in the Hartshorne and May studies, among others. If personality traits did not predict behavior that well, the argument went, then the variability of behavior across situations must be due to other factors, such as contexts.

Ultimately, this so-called Person-Situation Debate led many people to discount the utility of personality traits, as they appeared to fail to account for the rich variability in behavior within personality.

Two Fields of Personality

Perhaps the biggest legacy of the Person-Situation Debate was the seeming bifurcation in different approaches to understanding personality that we’ve discussed thus far – a nomothetic approach that emphasized variability between people and an idiographic approach that emphasized variability within a single person. Thus, the fall out was that some personality scientists responded to the challenges to the utility and validity of personality traits as the unit of personality by shoring up the measurement of personality traits. Others, however, focused on understanding variability, partially eschewing the need to study broad traits at all.

Social Cognitive Approaches

At the same time, other personality scientists decided to make variability, not consistency, their focus, attempting to understand how and why people varied over time. Mischel himself fell into this camp, going on to argue for social cognitive learning theories that emphasize bidirectional relationships between persons and the environments they inhabit. Depending on one’s motivations, people could behave differently in the same situation. For example, one’s behavior with the same friend would differ greatly when one is trying to convince the other of something than it would on average across a number of different motivational contexts.

Similarly, Albert Bandura, who has been ranked one of the most influential scientists of the 20th century, also set out to trying to understand how emerging work on social learning and cognitive approaches could inform how we understand how personality unfolds across situations and time.

Bandura and his colleagues’ work on social learning and self-efficacy and Mischel and his colleagues’ work on cognitive social learning theory and delay of gratification are largely grouped together under the header of social cognitive approaches to personality today. Social cognitive approaches can be considered another way to think about the structure of personality, more so in the vein of Allport’s idiographic work.

For example, some of Mischel’s later work with Yuichi Shoda, Jack Wright, and Phil Peake attempted to understand personality through a conditional view. Rather than thinking of personality structure as generalized tendencies across contexts, they argued that personality is better understand as a profile or if…then contingencies, or the conditional probability of engaging in a behavior given the presence of an objective or subjective situational feature, which you may remember Jaap Denissen discussing in the previous episode.

In a seminal series of studies, children being treated for behavioral disorders at the Wediko Summer Program in New Hampshire were observed by multiple individuals who rated them on a number of dimensions across different contexts (e.g., Mischel & Shoda, 1995; Shoda, Mischel, & Wright., 1994; Wright & Mischel, 1987). These studies demonstrated that children who exhibited similar mean levels of aggressive behaviors frequently had meaningfully different patterns of psychological precursors, such that some children were aggressive when threatened by peers but not when confronted by authoritative adults, while others showed the opposite pattern (Wright & Mischel, 1987).

Trait Approaches

In defense of broad, common traits, a number of researchers focused on the consistency of behavior over time, and the long term stability of these traits. The search to determine the most parsimonious set of broad, latent personality traits using data reduction techniques continued – in other words, such work sought to develop a taxonomy of how people differ from one another, somewhat akin to biological taxonomies of species. Although I could devote a whole 30 minute podcast just to the development of different taxonomies, or what Aidan summarized as the Big Few in the last episode, I will touch on the most prominent: The Big Five (and its variants).

The Big Five rose to prominence in the 1980s that has dominated the field ever since. The Big Five includes Extraversion, , Conscientiousness, Neuroticism, and / Intellect. Some of you may have heard these referred to with the acronym OCEAN or CANOE. The Big Five grew out of largely distinct work by both Lou Goldberg as well as Paul Costa and Robert McCrae, which grew out of earlier work by Donald Fiske, Warren Norman, and John Digman, among others.

The importance of the convergence of this work and the field “settling” on the Big Five cannot be overstated. After their development, personality scientists set about shoring up their measurement, as well as testing its robustness across age groups, countries, cultures, and time. In addition, establishing the predictive validity and utility of personality became a central focus of personalities scientists, as did the study of personality change, which we’ll touch on soon.

Personality Today

Since the rise of social cognitive approaches and the Big Five / taxonomic approaches, both approaches have set about establishing reliable and valid methods of measurement and establishing what personality, as conceived by both approaches, was associated with. In other words, to address a number of descriptive and predictive questions. Indeed, on the predictive side, for example, recent work by Chris Soto even collected new samples to test whether previous work of personality’s associations with life outcomes replicated. He found that personality-outcome incredibly replicable, particularly when compared to other replication projects in other areas of psychology.

I, along with my PhD advisor, Josh Jackson, also recently tested the robustness of personality- outcome associations as part of my dissertation. Using approximately 170,000 individuals from 10 longitudinal panel studies, we demonstrated that 14 personality characteristics, including the Big Five were robust predictors of 14 life outcomes, including health outcomes, mortality, marriage, divorce, unemployment, and contact with the criminal justice system. Moreover, we found that such associations were robust across covariates, and that there were few moderators of these personality-outcome associations that spanned decades.

On the other side, those interested in social cognitive approaches have become increasingly interested in how the study of dynamics can inform our understanding of idiographic personality structure, variability in manifestations of personality, and even addressing explanatory questions by investigating the causal underpinnings of personality. Such a shift in research was fueled in large part by the introduction of new techniques for collecting dynamic data, including experience sampling techniques where people respond to smaller subsets of questionnaires multiple times a day, daily diaries, audio data, and smartphone data.

For example, Will Fleeson and his colleagues expanded on early work by Cattell as well work by Marvin Zuckerman, David Buss, and Ken Craik. They argued that the observation that personality traits only predict behavior at about a .3 correlation level could be better understood by thinking of these behaviors as personality states collected via experience sampling that could be gathered into a density distribution. Properties of these density distributions of states, particularly the mean, should then be better associated with personality traits. They and others demonstrated reasonable convergence between traits and average states as well as the reliability of measures of variability, such as standard deviations.

Linking the states that social cognitive proponents have long studied to personality traits brought two bifurcated approaches closer to a reunion, particularly given that social cognitive mechanisms are considered to underly how and why variability exists at all. Indeed, the rise of the study of states has provided a productive period of research in personality.

But as I began my career, I wondered whether density distributions really did link nomothetic and idiographic approaches, or whether they were capturing something else entirely. For example, in some of my work, I used two waves of experience sampling data collected on some 300 people 4 times per day for two weeks one year apart. I used an approach called regularized graphical Vector Autoregression to investigate the idiographic structure of each of these individuals personalities.

What I found converged with earlier work by both Peter Molenaar as well as Peter Borkenau and Fritz Ostendorf indicating that idiographic personality structures diverge from between person structures. But it wasn’t just that items meant to tap Extraversion were associated with Agreeableness or Neuroticism for some but not all people.

What struck me more were two things. First, some of the indicators we measured just… didn’t appear to matter for some people. They weren’t associated with anything. Their variability was seemingly unpredictable, at least with the data we had. Second, some people showed no variability in their responses, for example reporting the lowest possible for anxiety at every measurement occasion (or even skipping just that item on most surveys).

All of this led me to wonder, does the lack of variability in anxiety these individuals showed mean they were very stably low in anxiety or was something else entirely going on. It reminded me of work on what are, with some arguing that emotions are characterized by appraisals, like certainty, positivity, or other responsibility. In one study of appraisals of emotions, Peter Kuppens and colleagues used a technique called 3 mode factor analysis to identify clusters of appraisals that preceded the experience of anger. Across the clusters of people, they found that there were differences in the appraisal underpinnings of anger. Their anger quite simply was different from others.

This reminds me of an Allport quote, which is “Whatever individuality is, it is not the residual ragbag left over after general dimensions have been exhausted” (Allport, 1968).

So here, I think it’s important to recognize that much of the study of within-person variability using density distributions is better considered just that – within-person. It’s not idiographic. Instead, the within-person is a different level of aggregation where the indicators that are measured typically match more directly or reflect experiences that most people are thought to have to some degree and at some times. To that end, unlike idiographic approaches, it often in part relies on understanding uniqueness in light of the ragbag leftover not explained by general dimensions. But unlike the between-person level, this level is more attuned to how a person varies. The idiographic level is a lower level of aggregation, where characteristics and experiences aren’t assumed to be shared and are more likely to capture lower level psychological processes, like attention, affect, and motivation. Or, as in the example Aidan Wright touched on in the last episode, differences in the degree and type of reinforcement processes underlying behaviors like alcohol use. The between-person level, in turns, captures differences between people on core dimensions.

There is much more to be said here. Many questions to ask and answer. But considering personality as its typically measured across these three levels of aggregation stands as an opportunity to continue to test how they relate to each other, including how a bunch of unique people display characteristics that have been reduced to a small number of parsimonious dimensions. Moreover, it provides new ways to think about description, prediction, and explanation. If there are differences in the type and degree of idiographic processes at the level of an individual, for example, then observing behaviors, like alcohol, may not give any indication of the underlying explanatory, or causal, phenomena. We can still describe, and perhaps, predict the behavior, but we can’t explain it. Thus, as it’s studied, addressing explanatory questions using nomothetic, between person approaches is unlikely to allow us to make causal conclusions. But continuing study of within-person and idiographic approaches may help us to build explanatory tests of why individuals behave in certain ways or the ever present question of “why they are like that.”

As Aidan mentioned, answering such questions requires that theoretical, data collection method, and statistical methods be aligned, and this is really hard. The misalignment of these is what some have called theory-method gap in which the theoretical questions or ideas we have don’t align with how we test questions the theory generates. Or sometimes we see this when work is done without theoretical guidance. Indeed, for me, it’s the theory-method gap that has pulled me deeply into the history of personality psychology. Allport as well as other theorists like Gerard Heymans, Henry Murray, Ross Stagner, Saul Rosenzweig, Jack Block, Walter Mischel, and others left a rich theoretical legacy about what personality is that remains largely untested.

My time runs short, and I still want to touch on personality change, so I’ll end with a few shout outs to important work that is currently ongoing in the study of personality structure. The attempt to understand the general dimensions that differentiate people is far from done. There are many valid criticisms of the Big Five as a descriptive taxonomic personality structure.

Some critiques revolve around the breadth of traits.

For example, Rene Mõttus and his colleagues have an ever-growing body of work demonstrating that narrower characteristics, including facets or nuances of Big Five dimensions, are often better predictors of outcomes than broad traits.

Others proceed from the observation that a number of seemingly core individual differences, like honesty, humor, and values are not captured within the Big Five.

For example, David Condon and Bill Revelle have pioneered work on using planned missing data to assess huge numbers of personality indicators. Through this, David demonstrated a 27 factor solution using hundreds of items collected across several hundred thousand people. David and Rene have also been working to use information theory to guide the construction of personality assessments.

Using more modern psychometric techniques with Ashton and Lee’s set of more than 1700 adjectives, Gerard Saucier and Kathryn Iurino similarly demonstrated a higher dimensional 21 factor solution better fits the data than a five factor solution.

Finally, others have more fundamental concerns with the measurement model used to “recover” the Big Five. For example, Alex Christensen and Hudson Golino have published a series of studies developing tools for using network techniques to investigate psychometric properties, including new tools for reducing redundancy in assessment. Their approach, which is rooted in the study of complexity, also represents an important theoretical contribution to thinking about how between-person personality differences arise.

Personality Changes So now that we’ve addressed what personality is, there’s a second question to address: Can personality change? Over the years and across disciplines, this question has been quite controversial. In part, this can be traced to differences in interpretation on what it means for one’s personality to change. But as personality psychologists understand it, personality change isn’t getting a whole new personality. Instead, personality change is about more gradual changes, regardless of whether we’re talking about changes in an individual’s unique configuration of their idiographic personality structure or about changes in the level or rank of a person on a population-level common trait. So, here’s the seeming paradox that’s not really a paradox – personality, regardless of how it’s defined, can be both relatively stable over time and also exhibit change.

Up until now, I’ve largely skirted the issue and question of personality change and development because much as how personality structure is a function of how personality is measured, personality change is also a function of measurement.

For example, if we measured broad, between-person personality traits using the Big Five, then change will be a function of that definition. Changes outside the Big Five will not be observed.

Although the study of personality change has deep roots, studying personality change was far from mainstream until the early 2000s. Before that, there were three pioneers of studying personality change, Ravenna Helson and Jack and Jeanne Block.

The Big Five were a critical development in the study of personality change. By allowing researchers to anchor on a core set of dimensions, it became possible to incorporate Big Five measures into existing longitudinal studies and even to reinterpret older scales in Big Five terms. In so doing, whether personality changes became less of a theoretical question and more of an empirical one.

Such investigations were additionally fueled by the introduction of more sophisticated statistical methods and the continuing rise of computing power, such as growth modeling for longitudinal data and meta-analysis for synthesizing previous studies.

In perhaps the most seminal study of personality change to date, Brent Roberts and his colleagues meta-analyzed a large number of studies of mean-level personality trait change in the Big Five. They found seemingly clear normative patterns of development across the lifespan, with Conscientiousness, Agreeableness, and Emotional Stability (the positive pole of Neuroticism) showing normative increases across the lifespan, Openness / Intellect showing increases in young adulthood before remaining relatively stable across the rest of the life span, and Extraversion showing differential change across facets.

Since then, Brent and his colleagues, including Jen Lodi Smith, Terri Moffit, Avshalom Caspi, Rick Robins, Josh Jackson, and many others too numerous to name have created an incredibly productive line of research investigating the underpinnings of normative change.

Indeed, the question of causes and consequences of change has been perhaps the largest looming question in the field for the last 20 years. Dan Mroczek and Ron Spiro, for example, used trajectories of personality change from the Veteran’s Affair Normative Aging Study to demonstrate that individuals showed differences in personality change across the lifespan, or so called interindividual differences in intraindividual change. More than that, they also demonstrated that these trajectories of personality change were longitudinally associated with mortality.

But the question of causes and consequences of change is far from straightforward. If the Big Five, for example, show patterns of normative change, then these may come from what Brent Roberts and Jen Lodi Smith have called the maturity principle and social investment theory. Essentially, personality traits tend to change toward higher levels of traits that are typically considered to be “good” or socially desirable. The changes tend to occur at points in the lifespan in which life events occur and social roles change, for example, entering the workforce, having children, and retiring.

Thus, one way to understand why traits change may be to test whether life events are associated with change. Thus, personality research set about investigating whether and which life events were associated with mean-level changes in personality. Despite numerous studies demonstrating life events associated with change, there are many inconsistencies in whether change is observed, the direction of change, and the degree of change that indicate the question is far from settled. In addition, selection bias, or how characteristics of individuals beyond personality may push individuals toward experiencing life events that may change their personalities, threatens how we understand change. Indeed, studies by Manon von Scheppingen, Jenny Wagner, Josh Jackson, and others demonstrate that many of these effects disappear when accounting for selection bias.

So, what are we missing? The simplest answer is that up until now, we’ve talked about only two kinds of change, which are very similar, mean level change in a population and interindividual differences in mean level change. In other words, in the aggregate, are levels of a personality characteristic changing and do people differ in the degree and direction of change?

But there are other methods with which to investigate personality change, two of which I will highlight here for the sake of time – rank-order and ipsative consistency/change. Rank order change, or consistency as the case may be, rank orders individuals on levels of a characteristic at two different time point and then correlates them. The resulting estimate gives a sense of whether individuals, regardless of how much they change, tended to maintain their position within the population. Higher rank order consistency suggests that people remain consistent. It does not, however, give any indication of how much people changed.

Next, ipsative change, of which Jack Block was the earliest and perhaps greatest proponent, stands apart from the methods discussed thus far because it does not concern a single personality trait and its change. Rather, ipsative change takes a set of characteristics of an individual at two time points and correlates the profile of their personality. Like rank-order consistency, this does not say anything about the amount of change observed in any characteristic. Rather, it tests whether the configuration of a single person’s personality is stable over time.

By focusing on an individual, moreover, ipsative change opens up the door for considering change outside of variable-centered, between-person trait dimensions. For example, in the study of mine I mentioned before, we created idiographic personality structures for our participants twice, once at each wave. We then took the profile of those structures at each wave for each person and correlated them. We found that these structures were relatively consistent over time but that there were individual differences in them. We have also demonstrated similar levels of consistency before and after the COVID-19 pandemic.

Conclusion

Each of these different types of change has rich historical roots and each has provided unique and important insights into personality. But much as the question of the structure of personality is both dependent on its definition and level of aggregation, so are questions of change. Moreover, questions of why change occurs remain largely open questions, much as do questions surrounding how to define personality structure.

My goal for today was neither to cover every relevant topic in personality structure and change nor to paint a full picture of them. Each of the topics I have touched on could easily have an entire episode devoted to them. Indeed, I’m quite certain they will.

So, for now, I’d like to thank you for listening and invite you back in the future for more discussions, talks, and more on the topics I’ve briefly introduced today. Selected References

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