Big Five personality traits predict small but robust differences in civic engagement.

OBJECTIVE: This preregistered study provides robust estimates of the links between Big Five personality traits and civic engagement across different samples and life stages. METHODS: We recruited two samples from the United States and United Kingdom (total N = 1593) and measured Big Five domains, Big Five aspects, and six civic engagement indicators: volunteerism, charitable giving, donating blood, posthumous organ donation, political voting, and vaccination. We compared the links between these measures across samples and tested moderation across life stages and several sociodemographic variables. We explored whether these links replicate between self- and peer-reports. RESULTS: We found small but robust effects. Agreeable, extraverted, and open/intellectual participants reported more civic engagement, especially volunteerism and charitable giving. Neurotic and conscientious participants mainly reported less civic engagement, especially blood and organ donations. One of the two Big Five aspects often drove these links, such as Compassion in the link between Agreeableness and volunteerism. We found some differences between younger and middle-aged adults. CONCLUSIONS: Big Five personality traits predict civic engagement modestly but consistently, with adequate study power being critical to detecting these links. Lower-order traits, such as Big Five aspects, clarify the relationships between traits and engagement. Life stages and sociodemographic variables have limited effects.

The impact of childhood lead exposure on adult personality: Evidence from the United States, Europe, and a large-scale natural experiment.

Childhood lead exposure has devastating lifelong consequences, as even low-level exposure stunts intelligence and leads to delinquent behavior. However, these consequences may be more extensive than previously thought because childhood lead exposure may adversely affect normal-range personality traits. Personality influences nearly every aspect of human functioning, from well-being to career earnings to longevity, so effects of lead exposure on personality would have far-reaching societal consequences. In a preregistered investigation, we tested this hypothesis by linking historic atmospheric lead data from 269 US counties and 37 European nations to personality questionnaire data from over 1.5 million people who grew up in these areas. Adjusting for age and socioeconomic status, US adults who grew up in counties with higher atmospheric lead levels had less adaptive personality profiles: they were less agreeable and conscientious and, among younger participants, more neurotic. Next, we utilized a natural experiment, the removal of leaded gasoline because of the 1970 Clean Air Act, to test whether lead exposure caused these personality differences. Participants born after atmospheric lead levels began to decline in their county had more mature, psychologically healthy adult personalities (higher agreeableness and conscientiousness and lower neuroticism), but these findings were not discriminable from pure cohort effects. Finally, we replicated associations in Europeans. European participants who spent their childhood in areas with more atmospheric lead were less agreeable and more neurotic in adulthood. Our findings suggest that further reduction of lead exposure is a critical public health issue.

National religiosity eases the psychological burden of poverty.

Lower socioeconomic status (SES) harms psychological well-being, an effect responsible for widespread human suffering. This effect has long been assumed to weaken as nations develop economically. Recent evidence, however, has contradicted this fundamental assumption, finding instead that the psychological burden of lower SES is even greater in developed nations than in developing ones. That evidence has elicited consternation because it suggests that economic development is no cure for the psychological burden of lower SES. So, why is that burden greatest in developed nations? Here, we test whether national religiosity can explain this puzzle. National religiosity is particularly low in developed nations. Consequently, developed nations lack religious norms that may ease the burden of lower SES. Drawing on three different data sets of 1,567,204, 1,493,207, and 274,393 people across 156, 85, and 92 nations, we show that low levels of national religiosity can account for the greater burden of lower SES in developed nations. This finding suggests that, as national religiosity continues to decline, lower SES will become increasingly harmful for well-being-a societal change that is socially consequential and demands political attention.

Self-Esteem and Income Over Time.

There is robust evidence that people with higher incomes tend to have higher self-esteem, but little is known about how changes in income and self-esteem are related within individuals. Some theories predict that increased earnings lead to higher self-esteem, others that increased self-esteem leads to higher earnings, and still others that there should be no within-person associations between these variables. We tested these theories in 4-year longitudinal data from more than 4,000 adult participants from a Dutch representative sample. Results indicated significant between-person associations between income and self-esteem, consistent with prior research. Within-person effects suggested that increases in self-esteem are a function of previous increases in income more than the other way around. These links held when analyses controlled for employment status, and they generalized across gender, age, and educational background. Overall, the findings provide evidence for theories that consider self-esteem as both a source and a consequence of personal earnings.

Personality, self-knowledge, and meat reduction intentions.

OBJECTIVE: Meat consumption has a host of serious negative consequences for nonhuman animals, underprivileged humans, and the natural environment. Several interventions have been developed to encourage meat reduction but to relatively limited effect. There is also a range of established predictors of meat consumption, but much less is known about the factors that predict intentions to reduce meat consumption. The goal of this study was to determine the roles of personality and self-knowledge in meat reduction intentions. METHOD: In this set of three preregistered studies, we tested brief interventions to encourage meat reduction intentions and examined personality predictors of intentions to reduce meat consumption. RESULTS: We found no evidence that brief interventions with or without a self-knowledge component had a meaningful effect on changing meat reduction intentions. However, we found robust evidence for relatively small associations between intending to eat less meat and high Openness to Experience, high Emotionality, and perceiving meat reduction as moral behaviors. CONCLUSION: Individual differences may be a more influential predictor of meat reduction intentions than brief interventions. Implications for promoting meat reduction are discussed.

Meta-analysis of personality trait differences between omnivores, vegetarians, and vegans.

Vegetarian and vegan diets have been increasing in the Western world. Recent research has focused on personality trait differences between dietary groups, in part because personality traits are broad characteristics that can integrate findings about different factors that motivate vegetarian or vegan diets. Previous research on personality predictors of vegetarian and vegan (veg*n) diet, however, has yielded inconsistent results. The goal of this study was to integrate the existing results of Big Five personality differences between veg*ns and omnivores as well as between vegetarians and vegans. To this end, we meta-analyzed data from 15 studies and N = 69,576 individuals from several countries. Results indicated that veg*ns were significantly higher in Openness (d = 0.40) and Agreeableness (d = 0.17) than omnivores, while vegans were significantly higher in Openness (d = 0.14) than vegetarians. This work isolates Openness and Agreeableness as important trait predictors of plant-based diets and sets the stage for future work on the factors that motivate vegetarian or vegan diet. Personality traits can provide an integrative framework for conceptualizing dietary preferences, be used to make predictions about the sources, course and correlates of dietary choices, and potentially be useful for advocates and policymakers seeking to tailor meat-reduction interventions.

Psychological change before and after religious conversion and deconversion.

OBJECTIVE: Theory and anecdotal evidence suggest that people undergo psychological changes before and after religious conversion and deconversion. Yet, existing research provided inconclusive evidence. Here, we examined psychological change before, during, and after institutional conversion and deconversion in a large-scale longitudinal study. METHOD: We used 11-wave longitudinal data from a nationally representative sample of Dutch adults (N ~ 20,000) to assess changes in religious beliefs and practices, personality traits, and well-being before, during, and after conversion to and deconversion from Christianity. RESULTS: Converts (N = 181) increased in service attendance and prayer, but not in their belief in God, as they approached conversion. Deconverts (N = 450) declined in religious beliefs and practices before, during, and after deconversion. In terms of personality, converts displayed small, unexpected declines in emotional stability, extraversion, and agreeableness at time of conversion. Deconverts declined in agreeableness, conscientiousness, and openness at time of deconversion. Neither group showed changes in their well-being. CONCLUSION: The present findings suggest that psychological changes during religious conversion and deconversion are generally small and mostly manifest as changes in people's religious beliefs and practices. Findings are discussed in the context of person-religion fit, meaning-making, and sociocultural motive perspectives on religious change.

Nature and Impact of Reference Group Effects in Personality Assessment Data.

People have a tendency to engage in social comparisons when evaluating and reporting on personality. This tendency and variation in who people compare their personality to is known as the reference group effect and has been largely discussed in cross-cultural research. However, reference group effects have implications beyond cross-cultural research and should be considered when collecting and interpreting personality data. In the present study, we examined the nature and impact of reference group comparisons on the Big Five personality traits in a sample of N = 1194 participants. Specifically, we examined what reference groups participants most believed they compared their personality to, and which reference group was actually the most impactful on trait scores. We found that most people believed they compared their personality to people in general. However, the most influential reference group was people the same age as the participants. Moreover, we found that people mostly engaged in between- as opposed to within-person comparisons when evaluating their own personality. Overall, our findings highlight that people have relatively little insight into the comparisons they engage in when make judgments on personality. Discussion focuses on theoretical and practical implications of our findings in light of personality assessment data.

Selection and socialization effects of studying abroad.

OBJECTIVES: Studying abroad is often considered a life-changing experience. However, research on studying abroad has not always disentangled selection from socialization effects, leading to uncertainty about the actual impact of this experience. In this 4-wave longitudinal study, we examined both selection and socialization effects of a 4-week intensive study abroad program on 17 psychosocial variables related to motivation, academic achievement, well-being, and self-reflection. METHOD: We used propensity score matching and multiple-group growth curve models to examine selection and socialization effects in a sample of sojourners (n = 145) and non-sojourners (n = 291). RESULTS: We found selection effects for several variables related to students' motivation and well-being. Contrary to our predictions, we found no evidence for socialization effects of studying abroad on any of the outcome variables. CONCLUSIONS: Students who are relatively more intrinsically motivated and emotionally healthy appear to be more likely to study abroad. However, studying abroad for one month does not appear to lead to meaningful and lasting psychological change, on average. Our results highlight the need to examine both selection and socialization effects of study abroad programs with longitudinal data and well-matched comparison groups.

Personality aspects and proenvironmental attitudes.

OBJECTIVE: Climate change is a serious threat. Personality psychologists can help address this threat by understanding what kind of people tend to endorse proenvironmental attitudes and engage in sustainable behavior. Previous research supports reliable associations between proenvironmental attitudes and personality traits. However, this research has generally aggregated different kinds of attitudes into a single composite and has focused on the domain level of personality traits. METHOD: This study explored how 10 lower-order aspects of the Big Five personality traits were related to eight different proenvironmental attitudes in three convenience samples from the United States (N = 1234; 1000) and the United Kingdom (N = 538). RESULTS: All five trait domains were related to at least one proenvironmental attitude across all three samples. Seven of eight proenvironmental attitudes could be predicted by one or more traits in all three samples. We also found evidence that the Openness aspect of Openness to Experience was a more consistent predictor of proenvironmental attitudes than the Intellect aspect. In contrast, there was little benefit in distinguishing between the aspects of other trait domains. We did not find evidence that age or political orientation moderated the associations between proenvironmental attitudes and personality. CONCLUSION: Results point to the need for more fine-grained research on individual differences in proenvironmental attitudes and behavior.

Assessing Personality Change: Introduction to the Special Section.

Both clinical and personality psychologists are interested in assessing personality change, although they have tended to approach the issue in different ways. In this paper we argue that both sub-fields should focus more on basic issues in the assessment of personality change, and that they would make more progress on this issue together than alone. This Special Section on the Assessment of Personality Change includes four papers by researchers working primarily in basic personality science. Each paper addresses specific ways to advance the assessment of personality change that have both basic and applied clinical relevance, but collectively they show how far the field still has to go.

Charting self-esteem during marital dissolution.

OBJECTIVE: The purpose of this study was to chart changes in self-esteem before and after marital dissolution to identify the factors that shape individuals' self-esteem during this life transition. METHOD: We analyzed 10 annual waves of self-esteem data from 291 divorcees from a nationally representative panel study of the Netherlands (N ~ 13,000). We charted the course of self-esteem before and after marital dissolution and tested a broad set of moderator variables that may shape individuals' self-esteem trajectories. RESULTS: The average divorcee experienced significant decrease in self-esteem preceding marital dissolution and remained stable afterward. There were substantial individual differences in self-esteem trajectories, both before and after marital separation. Divorcees who experienced financial hardship, were affiliated with a church or religion, or scored low in Conscientiousness showed the most pronounced decrease in self-esteem during the years approaching marital dissolution. CONCLUSION: This study highlights the importance of assessing people multiple times before and after marital dissolution to dissect how people approach and respond to this life event. Results are consistent with perspectives that view divorce as an opportunity to abate the strains of an unhappy marriage.

Development and validation of the motivations to Eat Meat Inventory.

Previous research suggests that there are four primary motives to eat meat: that it is natural, normal, necessary, or nice. However, these motives have not yet been distinguished empirically; the lack of a measurement tool that can distinguish these motives has contributed to a literature that focuses primarily on meat-eating motivation or justification in general, as opposed to differences between these motives. We developed a 19-item measure, the Motivations to Eat Meat Inventory (MEMI), that fit a four-factor model in three samples (total N = 2175), including one with a large number of vegetarians. Using this instrument, we generated psychological profiles associated with each motive, and showed that the structure and correlates of meat-eating motives is highly similar for omnivores and vegetarians. This research provides a valuable tool for studying variation in psychological motives for eating meat among both meat-eaters and vegetarians and provides an initial framework for understanding the underpinnings of these different motivations.

The Well-Being Benefits of Person-Culture Match Are Contingent on Basic Personality Traits.

People enjoy well-being benefits if their personal characteristics match those of their culture. This person-culture match effect is integral to many psychological theories and-as a driver of migration-carries much societal relevance. But do people differ in the degree to which person-culture match confers well-being benefits? In the first-ever empirical test of that question, we examined whether the person-culture match effect is moderated by basic personality traits-the Big Two and Big Five. We relied on self-reports from 2,672,820 people across 102 countries and informant reports from 850,877 people across 61 countries. Communion, agreeableness, and neuroticism exacerbated the person-culture match effect, whereas agency, openness, extraversion, and conscientiousness diminished it. People who possessed low levels of communion coupled with high levels of agency evidenced no well-being benefits from person-culture match, and people who possessed low levels of agreeableness and neuroticism coupled with high levels of openness, extraversion, and conscientiousness even evidenced well-being costs. Those results have implications for theories building on the person-culture match effect, illuminate the mechanisms driving that effect, and help explain failures to replicate it.

Self-other personality agreement and internalizing problems in adolescence.

OBJECTIVE: Achieving a clear self-view is a lifelong task that is particularly salient during adolescence. Theory and research suggest that close others' perceptions of individuals' personality may influence the formation and maintenance of coherent self-views. The degree to which adolescents develop a stable and coherent self-view, in turn, may have perennial influences on their mental health and well-being. This 1-year longitudinal study investigated the associations between the agreement of self- and other-rated Big Five personality traits and internalizing problems in adolescence. METHOD: Participants were 570 Dutch adolescents (51% girls), their mothers, friends, and siblings. We examined the cross-sectional and longitudinal associations between self-other personality agreement and internalizing problems using polynomial regression analyses and response surface analyses. RESULTS: Results indicated strong main effects of self- and other-rated personality traits on internalizing problems but provided little evidence for longitudinal associations between self-other personality agreement and internalizing problems. CONCLUSION: Our results cast doubt on the generalizability of the beneficial effects of self-other agreement documented in the adult literature to adolescents but highlight the importance of self- and other-rated personality in youth's mental health development. Discussion focuses on the theoretical implications and recommendations for future investigations of self-other agreement.

Age differences in Machiavellianism across the life span: Evidence from a large-scale cross-sectional study.

OBJECTIVE: Lifespan perspectives on personality development have gained much momentum in recent years, mostly focusing on benevolent and neutral traits such as the Big Five. Despite their strong associations with critical personal outcomes, surprisingly little research has investigated the development of malevolent traits. Addressing this gap, we examined age trends in Machiavellianism across the lifespan. METHODS: Using data from a large-scale cross-sectional sample (n = 1,118,643), we analyzed mean-level changes from age 10 to 67. RESULTS: Age differences in Machiavellianism were most pronounced as a strong upward trend during the transition from late childhood to adolescence, when it peaked. Throughout adulthood it exhibited a steady downward trend, reaching an overall minimum at age 65. Across the lifespan, Machiavellianism tended to be higher in men and high-income participants. Compared to Machiavellianism, the age trends in Agreeableness and-to a lesser extent-Conscientiousness showed almost perfectly polar opposite patterns. CONCLUSIONS: Age trends in malevolent personality conform to established patterns of normative change, indicating temporary disruption in adolescence and social maturation across adulthood. The results advance theory and research on personality trait development across the lifespan and highlight crucial developmental windows that can inform targeted interventions to keep socially aversive traits in check.

Using Machine Learning to Advance Personality Assessment and Theory.

Machine learning has led to important advances in society. One of the most exciting applications of machine learning in psychological science has been the development of assessment tools that can powerfully predict human behavior and personality traits. Thus far, machine learning approaches to personality assessment have focused on the associations between social media and other digital records with established personality measures. The goal of this article is to expand the potential of machine learning approaches to personality assessment by embedding it in a more comprehensive construct validation framework. We review recent applications of machine learning to personality assessment, place machine learning research in the broader context of fundamental principles of construct validation, and provide recommendations for how to use machine learning to advance our understanding of personality.

Does Openness to Experience matter in love and work? Domain, facet, and developmental evidence from a 24-year longitudinal study.

OBJECTIVE: Although numerous studies have demonstrated that personality traits predict important love and work outcomes, there is mixed evidence for the relevance of Openness to Experience to love and work. We sought to better understand the long-term consequences of Openness in these two domains. METHOD: We examined the associations between Openness and 51 love and work outcomes using data from a 24-year longitudinal study of UC Berkeley students (N = 497) followed from the beginning of college into midlife. Using latent growth curve modeling, we examined whether Openness levels and change in Openness from college to midlife were associated with downstream love and work outcomes. Additionally, we tested whether three facets of Openness (intellectual interests, aesthetic interests, and unconventionality) had differential associations with outcomes. RESULTS: Although stable levels of Openness predicted few work or love outcomes, individual differences in Openness change were associated with delayed romantic commitment and some career outcomes. In addition, there were significant differences among facets of Openness: intellectual interests were highly associated with educational outcomes, whereas aesthetic interests and unconventionality predicted nontraditional career motivations. CONCLUSIONS: We situate these results in past research on real-world consequences of personality traits and discuss implications for theory and future research.

Uncovering the Power of Personality to Shape Income.

The notion of person-environment fit implies that personal and contextual factors interact in influencing important life outcomes. Using data from 8,458 employed individuals, we examined the combined effects of individuals' actual personality traits and jobs' expert-rated personality demands on earnings. Results from a response surface analysis indicated that the fit between individuals' actual personality and the personality demands of their jobs is a predictor of income. Conclusions of this combined analysis were partly opposite to conclusions reached in previous studies using conventional regression methods. Individuals can earn additional income of more than their monthly salary per year if they hold a job that fits their personality. Thus, at least for some traits, economic success depends not only on having a "successful personality" but also, in part, on finding the best niche for one's personality. We discuss the findings with regard to labor-market policies and individuals' job-selection strategies.

Individual differences in personality change across the adult life span.

OBJECTIVE: A precise and comprehensive description of personality continuity and change across the life span is the bedrock upon which theories of personality development are built. Little research has quantified the degree to which individuals deviate from mean-level developmental trends. In this study, we addressed this gap by examining individual differences in personality trait change across the life span. METHOD: Data came from a nationally representative sample of 9,636 Dutch participants who provided Big Five self-reports at five assessment waves across 7 years. We divided our sample into 14 age groups (ages 16-84 at initial measurement) and estimated latent growth curve models to describe individual differences in personality change across the study period for each trait and age group. RESULTS: Across the adult life span, individual differences in personality change were small but significant until old age. For Openness, Conscientiousness, Extraversion, and Agreeableness, individual differences in change were most pronounced in emerging adulthood and decreased throughout midlife and old age. For Emotional Stability, individual differences in change were relatively consistent across the life span. CONCLUSIONS: These results inform theories of life span development and provide future directions for research on the causes and conditions of personality change.