Is defined as both the consistencies in people and the ways people change over time?

Measuring personality change

Personality change comprises different forms of change in different aspects of personality. Most studies within personality psychology are based on the Big Five model (John, Naumann, & Soto, 2008) and therefore this chapter will focus on this model as well. It is based on the idea that every meaningful personality trait is represented in language and therefore part of a (comprehensive) dictionary. Thus all traits that can be identified in dictionaries were collected in large samples of individuals and condensed using factor analytical techniques. The Big Five model summarizes the large number of personality traits into a hierarchy with five personality factors at the highest level of abstraction (i.e., emotional stability, extraversion, openness to experience, agreeableness, and conscientiousness). The Big Five have been replicated by a large number of scientists across a large number of age groups, languages, and cultures.

Personality change has often been examined using two population indices, namely mean-level changes and rank-order consistencies. Mean-level changes describe how the average levels of single personality traits in groups of same-aged individuals change across time. Mean-level increases reflect that a personality trait—on average—increases in an age group whereas mean-level decreases reflect that the respective personality trait—on average—decreases in an age group. Mean-level changes do not inform about how single individuals change across time or about how similar individuals change within an age group across time.

Rank-order consistencies describe how stable the ordering of individuals in groups of same-aged individuals is on single personality traits across time. High rank-order consistencies reflect that individuals remain their relative ordering on a personality trait. That is, individuals who were among those with the highest, medium, and lowest trait values tend to have the highest, medium, and lowest trait values, respectively, across time. Low rank-order consistencies, in contrast, reflect that individuals change their relative ordering. For example, individuals who were among those with the highest trait values might have lower trait values than others of that age group at later time points. Similarly, those with low trait values might, for example, have higher trait values than others of their age group at later time points. Rank-order consistencies do not inform about how single individuals change across time or whether the average level of a personality trait increases or decreases with time. Further details on how rank-order consistency informs about developmental processes are provided by Fraley and Roberts (2005).

Another, somewhat less frequently used, approach for examining personality change focuses on changes in personality profiles or personality types instead of single traits. It aims at describing personality in a more holistic way by considering several traits at once. Most often, at least three personality types with distinct personality profiles are distinguished: resilients, overcontrollers, and undercontrollers (Asendorpf, 2015). Resilient individuals are characterized by profiles with comparatively high values in emotional stability and all of the other four Big Five traits. In contrast, undercontrollers are characterized by profiles with comparatively low values in agreeableness and conscientiousness whereas overcontrollers are characterized by profiles with comparatively low values in extraversion and openness to experience (Specht, Luhmann, & Geiser, 2014). Changes in type membership generally require changes of either several personality traits simultaneously or change in one personality trait that is comparatively strong. Thus personality type membership tends to be relatively stable across time.

There are lots of other forms of conceptualizing and measuring personality change that have been largely neglected so far. Ozer (1986) provides a comprehensive overview on a large number of these. It includes, among others, information on stability (and change) in the structure of personality across time and/or age groups and similarities in developmental trends either across individuals or across personality traits. Whereas a high number of studies confirm that the structure of personality remains largely stable across time (which is a precondition for a straightforward test of the stability in mean levels and rank ordering), there is a lack of knowledge about how personality changes using other than the above-mentioned approaches. A deeper understanding in this regard would enable to gain insight into individual differences and processes of personality development.

Frontotemporal Dementia Syndrome

The dementia syndrome of frontotemporal type is less common than the dementia syndrome of Alzheimer's type and should be described here in outline only (Brun et al., 1994). The major feature of this syndrome is a change in personality. Features of the dementia syndrome of Alzheimer's type, like predominantly amnestic and apractic signs, or a decrease in intellectual functions, are not detectable during early stages of the frontotemporal dementia syndrome.

The personality change comprises changes in the way of experiencing certain situations, in the way of reacting in certain situations, or in the way a person was used to acts spontaneously.

Lack of expected reactions or actions. The patient is aspontaneous and does not react as they did before the onset of the dementia syndrome. At times, a lack of drive is noted. As there is no emotional symptom of depressed mood and despair, this has been named pseudodepression.

Disinhibition. A lack of control of intentions, especially with respect to social norms or cultural restraints, is observable.

Perseveration and stereotyped behavior. The patient reiterates actions and is inflexible in the way of reacting.

Lack of insight and disorder of judgment, as described above (see section Cognitive Neuropsychological Signs).

In addition to the psychopathological symptoms described above, formalized neuropsychological testing reveals deficits in planning, in shifting mental set, and in working memory. The frontotemporal dementia syndrome can be identified clinically only in early stages. In late stages, mostly an unspecific terminal dementia syndrome is clinically observed.

As for the dementia syndrome of Alzheimer's type, also in frontotemporal dementia there is a heterogenous etiology with mostly genetically determined underlying diseases.

Health interventions

Can health status alter and ultimately change personality traits? The best potential evidence for a causal link between health and personality trait development is through a health intervention, where the intervention has an unintentional effect of changing personality. Unfortunately, studies that are able to successfully intervene to influence physical health status typically do not assess personality before and after the intervention, so few studies of this kind exist. Overall, the limited evidence points to a minimal influence of health interventions on personality. In a meta-analysis of interventions to improve the health of those with coronary heart disease (e.g., behavior modification and health education), there were no subsequent changes in trait anxiety or depression, the only individual difference variables assessed (Dusseldorp, Van Elderen, Maes, Meulman, & Kraaij, 1999).

One difficulty in parsing the health intervention literature (e.g., Glanz & Bishop, 2010) is that many health interventions focus on changing health behaviors (e.g,. exercise, diet) that are conceptually related to personality traits such as conscientiousness (Jackson & Roberts, in press). For example, though health interventions typically are effective at influencing health behaviors related to the trait of conscientiousness (e.g., exercise, Marcus et al., 1998), the above meta-analysis did not assess the trait of conscientiousness; thus, it is unknown whether the intervention had any effects on levels of conscientiousness. Despite the lack of evidence, there exists enthusiasm that personality may change in response to interventions targeted at particular health behaviors (e.g., substance abuse; Magidson, Roberts, Collado-Rodriguez, & Lejuez, 2014). While promising, these studies blur the line between health status, the processes that change health, and indicators of personality.

Discussion

A comprehensive treatment of methods to study personality change is clearly beyond the scope of a book chapter. Rather, the purpose of this chapter was to provide a bird’s eye perspective on popular approaches, identify some general trends, discuss common problems, and point the reader to ongoing developments. At the broadest level, we have argued that the study of personality change has progressed from the analysis of simple mean differences and average trajectories to the study of within-person (causal) dynamics. Likewise the methods used for longitudinal data analysis in personality psychology have changed over time and continue to develop. Accordingly, we have not only introduced different approaches, but have highlighted several shortcomings of existing methods and have pointed to recent developments that may help to overcome these problems. Rather than discussing technical details, however, we have limited ourselves to briefly sketch the general idea of each method, and to provide references for more detailed information. In addition, we used a simple example dataset to illustrate each approach and provide code for most of the models discussed. We encourage the reader to explore this code in order to gain a better understanding of each of the models. Furthermore, the code may be easily adapted to one’s own research purposes. We thus hope, the chapter may not only provide an overview of existing approaches to study personality change, but may also serve as an inspiration to try out new—better—ways of data analysis.

Abstract

An emerging body of research has begun to examine volitional personality change—people’s desires and attempts to change their own personality traits. Studies have found that the vast majority of people want to change aspects of their personalities—usually in order to attain an external goal (e.g., wanting to increase in extraversion in order to achieve more satisfying social relationships). Moreover, several studies have found that people may actually be able to moderately and slowly change their personality traits in desired ways—at least over a short period of time. As the literature on volitional personality change is in its infancy, much future research is needed to understand which strategies for volitional change are most efficacious, and whether volitional trait changes can be maintained over extended periods of time.

State processes and personality trait stability and change

We have defined personality characteristics as relatively enduring individual differences in a wide range of connected state processes. Consequently, personality development can be understood as stabilization and changes of these individual differences in state processes. Following our generic model, the existence of coherent personality differences and the comparatively strong stability of these differences can be well explained by the firm connection between processes within and across process domains. This is in line with the idea of personality stabilization due to individual differences in the reaction to and the selection, evocation, and manipulation of environmental information (Caspi & Roberts, 1999), and the self-reinforcing nature of social information processing mechanisms (e.g., Crick & Dodge, 1994; Nickerson, 1998). Similarly, individual state network perspectives conceptualize traits as individual differences in networks of connected state components. These state components are thought to be linked in a way that they mutually reinforce each other for causal, homeostatic, or logical reasons (see Cramer et al., 2012, for details). Thus, within individuals, states tend to develop into stable configurations (i.e., behavioral equilibriums) that underlie the strong temporal stability of globally assessed personality traits.

At the same time, the outlined personality processes point at potential ways of personality change. In principle, any of the outlined processes can be subject to change, thereby affecting other processes and potentially leading to a relatively enduring change in the levels of state expressions and in state contingencies (i.e., individual state networks reach a new equilibrium), that is, to personality trait change. The ease and effectiveness by which a given state change leads to personality change should depend on the strength and frequency of state change and on how strongly it is connected to other state aspects (i.e., the centrality of a state in an individual network). Changes in one state might push other states to similar levels (leading to permanent change) or, alternatively, these other states might pull the changed state back to its previous state level (leading to momentary fluctuations).2

4.4.2 Developmental Change in Personality Traits During Childhood

When considering the development of personality during childhood, one interesting issue is that of personality change during these formative years. That is, for any given personality characteristic, do children typically tend to show increasing, decreasing, or stable levels? One study by Lamb, Chuang, Wessels, Broberg, and Hwang (2002) addressed this question by examining the personalities of about 100 Swedish children at various time intervals during a 13-year period. The first personality assessments were made when the children were 2 years old, and further assessments were made at ages 3, 6, 8, and 15 years. All of the assessments were obtained using mothers' reports of their children's personalities in terms of the Big Five personality factors.

Lamb et al. (2002) found that, across the duration of the study, the typical child became lower in Extraversion, higher in Agreeableness, and higher in Conscientiousness. These differences were moderately large, being roughly one standard deviation unit in size. In addition, the children typically became somewhat lower in Emotional Stability between the ages of 3 and 6 years (i.e., during the period when they began school), and most became somewhat lower in Openness to Experience between the ages of 8 and 15 years (i.e., during the period when they reached adolescence).

It is interesting to speculate on the possible reasons for these patterns of developmental changes. For example, Lamb et al. (2002) suggested that the demands imposed by the educational system tended to make children become more conscientious throughout their childhoods, and perhaps a similar suggestion could be offered for Agreeableness. However, these results are based on only one investigation, and future research will be needed to find out whether the results will apply to children in general. The interpretation of these findings is complicated by the fact that the personality trait scales had low reliabilities during the early periods, especially Extraversion and Openness to Experience. This low reliability might reflect one of the difficulties in examining developmental change in children's personality: Because children's personalities are expressed in terms of different behaviors as they grow older, it might not be possible to assess personality by using reports of the same behaviors at different ages.

3 Client-centered Therapy

Rogers' approach to counseling and psychotherapy was based on a core hypothesis about human growth and personality change, which he summarized in 1950:

Client-centered therapy operates primarily upon one central and basic hypothesis which has undergone relatively little change with the years. This hypothesis is that the client has within himself the capacity, latent if not evident, to understand those aspects of his life and of himself which are causing him pain, and the capacity and the tendency to reorganize himself and his relationship to life in the direction of self-actualization and maturity in such a way as to bring a greater degree of internal comfort. The function of the therapist is to create such a psychological atmosphere as will permit this capacity and this strength to become effective rather than latent or potential.

While other therapies might profess similar belief, Rogers' method of creating the therapeutic psychological atmosphere was radically different from other approaches commonly employed. Avoiding questions, interpretation, or other directive techniques, Rogers' initial ‘nondirective method’ relied exclusively on careful listening and skillful ‘reflection of feelings,’ leading to client insight and positive action. Although he always remained primarily nondirective in his practice, Rogers soon recognized that the counselor's attitudes were more important than his particular techniques. Still later he clarified that it was the therapeutic relationship, which the attitudes helped create, that was growth producing. Rogers called this therapeutic relationship ‘client-centered’ and described three key ‘conditions’ in the relationship that bring about positive change in clients.

First is to accept the client as he or she is, as a person of inherent worth possessing both positive and negative feelings and impulses. Rogers called this acceptance and prizing of the person ‘unconditional positive regard.’ Second is ‘the therapist's willingness and sensitive ability to understand the client's thoughts, feelings, and struggles from the client's point of view … to adopt their frame of reference.’ Third is to be ‘genuine, or whole, or congruent in the relationship … It is only as [the therapist] is, in that relationship, a unified person, with his experienced feeling, his awareness of his feelings, and his expression of those feelings all congruent or similar, that he is most able to facilitate therapy.’

When a counselor communicates this unconditional positive regard, empathic understanding, and congruence so that the client perceives them, the ‘necessary and sufficient conditions for therapeutic personality change’ are present. Rogers argued and demonstrated that clients have within themselves the ability and tendency to understand their needs and problems, to gain insight, to reorganize their personality, and to take constructive action. What clients need is not the judgment, interpretation, advice, or direction of experts, but supportive counselors and therapists to help them rediscover and trust their ‘inner experiencing’ (a concept borrowed from Gendlin), achieve their own insights, and set their own direction.

Client-Centered Therapy

Rogers' approach to counseling and psychotherapy was based on a core hypothesis about human growth and personality change, which he summarized in 1950:

Client-centered therapy operates primarily upon one central and basic hypothesis which has undergone relatively little change with the years. This hypothesis is that the client has within himself the capacity, latent if not evident, to understand those aspects of his life and of himself which are causing him pain, and the capacity and the tendency to reorganize himself and his relationship to life in the direction of self-actualization and maturity in such a way as to bring a greater degree of internal comfort. The function of the therapist is to create such a psychological atmosphere as will permit this capacity and this strength to become effective rather than latent or potential (p. 443).

While other therapies might profess similar beliefs, Rogers' method of creating the therapeutic psychological atmosphere was radically different from other approaches commonly employed. Avoiding questions, interpretation, or other directive techniques, Rogers' initial ‘nondirective’ method relied exclusively on careful listening and skillful ‘reflection of feelings,’ leading to client insight and positive action. Although he always remained primarily nondirective in his practice, Rogers soon recognized that the counselor's attitudes of acceptance and understanding were more important than his particular techniques. Still later he clarified that it was the relationship in therapy, which the attitudes helped create, that was growth-producing. Rogers called this therapeutic relationship ‘client-centered’ and described three ‘core conditions’ in the relationship which bring about positive change in clients.

The first is to accept the client as he is, as a person of inherent worth possessing both positive and negative feeling and impulses. Adopting a term coined by his student Stanley Standal, Rogers called this acceptance and prizing of the person ‘unconditional positive regard.’ The second is “the therapist's willingness and sensitive ability to understand the client's thoughts, feelings and struggles form the client's point of view…to adopt his frame of reference” (1949: 84). Rogers used the term ‘empathy’ to describe this condition, popularizing a concept already in use in the field. The third is, be “genuine, or whole, or congruent in the relationship…It is only as [the therapist] is, in that relationship, a unified person, with his experienced feeling, his awareness of his feelings, and his expression of those feelings all congruent or similar, that he is most able to facilitate therapy” (pp. 199–200). He most often used ‘congruence’ to describe this third ingredient of the therapeutic relationship.

When a counselor is in psychological contact with a client and is able to communicate these attitudes so that the client can perceive them, the ‘necessary and sufficient conditions for therapeutic personality change’ are present. Rogers argued and demonstrated that the client has within himself the ability and tendency to understand his needs and problems, to gain insight, to reorganize his personality, and to take constructive action. What clients need is not the judgment, interpretation, advice, or direction of experts, but supportive counselors and therapists to help them rediscover and trust their ‘inner experiencing’ (a concept borrowed from Gendlin), achieve their own insights, and set their own direction.

Until Rogers, the fields of counseling and psychotherapy had been dominated by the guidance movement and psychoanalysis, respectively. While Rogers was not the first to argue for a ‘newer approach’ to counseling and psychotherapy – an approach that relied less on the professional's expertise and direction and more on the client's direction and resources – Rogers' system was arguably the most clearly described, comprehensive, and extreme, and the newer direction in mental health work became associated with him.

Major Illness as a Predictor of Personality Change

To this point, we have focused on the role of positive health outcomes and behaviors on personality change and development. However, equally, if not more, intriguing is the potential for negative health outcomes and major health-related struggles to influence personality change. This intrigue comes from the fact that one could easily expect significant findings to occur in either direction. Individuals who experience a life-changing medical event (e.g., stroke, heart attack, etc.) may fall into a depressogenic mindset and be more likely to perceive that their health outcomes are beyond their control; in turn, these individuals could focus less on living a self-controlled, emotionally stable lifestyle and thus experience personality corruption as a result. Alternatively, experiencing such an event might shake individuals from their initially negative lifestyles, and redirect them toward a more conscientious and less neurotic path. The second possibility may prove particularly likely given that individuals who experience negative health events are likely to be lower on adaptive personality traits in the first place (Goodwin & Friedman, 2006; Hampson, 2012).

Though limited, research has demonstrated a complex set of results that support both possibilities. For instance, one study of Finns found that emerging adults diagnosed with a chronic disease were more likely to remain introverted and neurotic than their peers (Leikas & Salmela-Aro, 2015). However, this life event also was associated with the potential for becoming more conscientious with time. Among older adults, work suggests that reporting a greater disease burden predicts becoming more conservative and less open to new experiences (Sutin et al., 2013), a change that could help individuals avoid future disease exposure, but also potentially increase mortality risk (Turiano, Spiro, & Mroczek, 2012). In addition to these longitudinal findings, more retrospective work has suggested that observers (e.g., caregivers, family, friends) often report changes in personality among patients experiencing Alzheimer’s disease or stroke (Stone et al., 2004), typically in the negative direction. In sum, research points to the potential for individuals to change their personalities following a major health concern in both adaptive and maladaptive ways, often depending on the illness in question. Research thus should potentially compare self-reports and observer-reports for the traits in question, as observers could pick up on changes less discernible to the patient, which serves as one direction for future work.