Chapter 10

Meaning and Future of Intelligence-Personality Relations

CHAPTER SUMMARY

1. Implications and future directions
   1. Personality and intelligence research:
      1. Many cognitive abilities are correlated with a variety of personality constructs. Therefore, measuring a given cognitive ability construct is likely to give some indication of a set of personality constructs.
      2. Long term retrieval constructs have a distinct nomological network from long term learning constructs and therefore should be distinguished.
      3. Several knowledge acquisition trait complexes identified in Ackerman and Heggestad’s previous meta-analyses (1997) are supported but with the addition of many personality traits from various levels of the personality hierarchy (e.g., factor beta, compassion, order, and achievement via independence).
      4. Bandwidth fidelity: Relations between constructs at commensurate levels of bandwidth were not stronger than other relations (i.e., we did not find stronger relations between constructs at similar levels of the cognitive and personality hierarchies).
   2. Etiology of personality and intelligence:
      1. Personality constructs and their etiological bases (e.g., hormonal, genetic) should be incorporated into models of prefrontal cortex function along with the impact of environmental resources and threats (e.g., nutrition, domestic violence).
   3. Estimates of trait overlap inform utility forecasts for personality and cognitive ability measurements.
2. Insights into human individuality and diversity:
   1. Fit between the environment and the individual depends on the latter’s goals.
   2. Fitness manifests across life domains as mental well-being, professional effectiveness, educational attainment, and longevity, among others.
   3. At the individual level, psychological fitness may be maximized by modulating expression of trait complexes to meet varying environmental demands.
   4. Our environment and goals are dynamic, so there is no single optimal human profile; diversity is optimal.
   5. At the population level, odds of species survival are maximized by diversifying individuals’ predispositions toward certain strategies and their corresponding trait complexes to meet a wide range of environments.
   6. Agility to adapt oneself and one’s goals to various environments or to find better-fitting environments is a common thread of effective individuals, but even agility requires tradeoffs.
   7. Cybernetic Trait Complexes Theory (CTCT) acknowledges that each of us must prioritize finite resources among competing goals and strategies. Our trait constellations guide how we approach these challenges and help us balance homeostasis and change as the environment demands in order to survive and thrive.

Implications and Future Directions

This book reported 3,543 meta-analyses that indicate numerous associations between cognitive abilities and personality traits. These relations have implications for the etiology of these domains as well as for explanation and prediction.

Cognitive Ability and Personality Research

The current study has three major implications for individual differences research. First and foremost, many cognitive abilities are correlated with a variety of personality constructs. Therefore, measuring a given cognitive ability construct is likely to give some indication of a set of personality constructs. For example, scoring high on mathematical abilities tends to indicate higher standing on industriousness and the ideas facet of openness but lower standing on politeness, modesty, and orderliness. Second, the nomological network of relations with long term retrieval constructs supports its distinction from long term learning constructs. Third, the knowledge acquisition trait complexes identified by Ackerman and Heggestad (1997) were mostly supported but with the addition of many personality traits from various levels of the personality hierarchy (e.g., factor beta, compassion, order, and achievement via independence). Similarly, the findings inform investment theories of intelligence in how personality guides the acquisition of knowledge. For example, since conscientiousness’ industriousness and order components as well as neuroticism’s uneven tempered and suspiciousness facets correlate notably with verbal abilities, developmental and theoretical models should incorporate these traits. Future research should also add contemporary conceptualizations of interests, values, and preferences to the present findings (cf. Hansen & Wiernik, 2018; Wiernik, 2016) to fully document the constitution of each trait complex.

Additionally, the overarching pattern of results is relevant to the bandwidth-fidelity dilemma. Most notably, we did not find stronger relations between constructs at similar levels of the cognitive and personality hierarchies. Instead, personality constructs and cognitive ability constructs cluster in complexes indicative of diverse fitness strategies.

As mentioned previously, general fitness refers to “individuals’ agility in effectively moving between a focus on surviving and a focus on thriving as the environment demands/provides” (see Chapter 5). Other researchers have described a fitness factor as “an index of general genetic quality that predicts survival and reproductive success” (Arden et al., 2009 p. 581). In both cases, fitness is conceptualized as conferring surviving and thriving. However, Arden et al.’s explanations focus on genetic causality and are more geared toward population-level effects. Our conceptualizations are built upon data from individuals and thus describe the psychologically functional interplay between abilities and personality in response to environmental demands and affordances. Therefore, fitness is relative to a specific environment (Sober, 2001).1 There are no ability-personality constellations that uniformly imbue individuals with greater fitness across all environments. As Nettle (2006) points out, variation in personality traits has been maintained over human evolution because of benefits and trade-offs across the continua of those traits that may confer differential advantages/disadvantages depending on a given environment. As we established through the research presented in this volume, abilities and personality traits that galvanize cybernetic mechanisms to achieve homeostasis for self-preservation and to activate change for self-development covary and may casually explain behavior. As such, their relations are central to the CTCT perspective we proposed, and they deepen understanding of personality-cognitive ability relations. Future research should examine the precise casual mechanisms involved.

Etiology of Personality and Cognitive Ability

The notable clusters of individual differences related to homeostasis and change identified by our review may be useful for directing the attention of researchers to investigate shared roots. Genetic (Deary et al., 2006; Hill et al., 2018; Sanchez-Roige et al., 2018), neurobiological (Allen et al., 2017; Deary et al., 2010), cultural (Lynn & Mikk, 2007; Schaller & Murray, 2008), educational (Chen et al., 2018; Dahmann & Anger, 2014; Ritchie et al., 2015), and other factors constituting the etiology of cognitive abilities and personality traits have been examined. The personality-cognitive ability links documented in this research can help researchers examine additional etiological factors that may have been overlooked or understudied and organize these factors around theoretically and empirically meaningful clusters.

For example, it is acknowledged that, “genes do not act directly on behavior; genetic effects are mediated by brain function and structure.” (Wilt & Revelle, 2017 p. 34). For agentic traits, such as extraversion, dopaminergic activity is a primary etiological basis (Depue, 1995; Depue & Collins, 1999; DeYoung, 2013). Our finding that extraversion’s activity and dominance facets as well as behavioral activation traits (e.g., achievement via independence) are related to several cognitive abilities may suggest a role for the dopaminergic system in cognitive activation for change. In support of this idea, research has documented links between various aspects of the dopamine system and memory (e.g., Luciana et al., 1998) as well as learning (Klingberg, 2010; Schultz, 2002; Wise, 2004). Yet dopamine’s role in acquisition of knowledge and the investment theory of cognitive ability has yet to be fully described and empirically documented. Behavioral activation traits’ pervasive relations with cognitive abilities suggest a ripe area for future research. More generally, our findings underscore a need to incorporate personality constructs and their other known etiological bases (e.g., hormonal, genetic) into models of prefrontal cortex function (e.g., Miller & Cohen, 2001). Many other biological and environmental factors await identification of their influences on personality and cognitive abilities. As researchers from a diverse set of fields review and contemplate the personality-cognitive ability relations documented here, they will be in the best position to consider and research shared etiological factors.

Considering environmental factors, it is certain that some experiences can have a significant, negative impact on cognitive abilities (e.g., head trauma). Detrimental effects of malnutrition on cognitive development have also been documented (e.g., Gillberg et al., 2010; Neumann et al., 2007; Prado & Dewey, 2014). Given the sizable, negative correlations between cognitive abilities and depression, a natural question is whether conditions that result in resource deficiencies and reduce the availability of psychological energy (e.g., malnutrition and famine-like conditions such as anorexia nervosa) constitute a shared cause. Some evidence for this has been reported from the Dutch famine during World War II (e.g., Roseboom et al., 2011). In the same way, personality traits such as neuroticism are affected by environmental influences (e.g., divorce, job promotion; Laceulle et al., 2013). Such relations may indicate concerted, intra-life adaptations to reorient the organism’s life strategy in response to strong environmental influences. We expect that, as researchers from a diverse set of fields review and ponder the multitude of personality-cognitive ability relations documented here, there will be many other shared etiological factors that will eventually be identified and understood.

Prediction of Behavior and Outcomes

The current research informs estimates of the joint utility of personality and cognitive ability measurements in the prediction and understanding of important behaviors and outcomes. For example, even though the associations of personality traits and cognitive abilities with a variety of important life behaviors and outcomes are well-known (e.g., Gottfredson, 1997; Lubinski, 2009; Roberts et al., 2007), the incremental utility of individual differences from each domain over the other in explaining and predicting behaviors and outcomes can only be estimated and understood by knowing the overlap between the two. That is, establishing the direction and degree of overlap between personality and cognitive ability variables enables the estimation of the incremental usefulness of each.

For example, a university that uses aptitude tests to predict high school students’ future learning success (e.g., measured by university grades) may consider adding a personality assessment of conscientiousness. Similarly, a company that uses personality measures to predict employees’ leadership potential may consider adding an assessment of reasoning ability. The current meta-analyses provide information crucial to the estimation of how much additional predictive value would be gained and, therefore, if the personality assessment is worthwhile.

Similarly, both cognitive ability and personality traits display significant relations in predicting career success metrics, such as salary (Ng et al., 2005). Cognitive ability is the single most potent psychological predictor of job performance, across jobs, with strongest effects in complex jobs (Dilchert, 2018; Ones et al., 2016). Many organizations rely on verbal ability tests or general mental ability measures in selecting their employees and managing their talent. Based on the current findings, one would know that verbal abilities are more strongly related to ambition than general mental ability is, and this important consideration could be leveraged to build a selection system that is more predictive of job performance.

There are many insights among the more than 3,500 meta-analytic relations presented here that specialists could use to better predict and understand behaviors and outcomes in their own fields. By using a large amount of data to form robust estimates of personality-cognitive ability relations, it is now possible to estimate the unique contributions of each personality trait and cognitive ability in domains such as education, work, intrapersonal, and social, among others.

Beyond predicting outcomes, CTCT could be used to help people understand themselves and identify their optimal environment. Currently, most people are not in the optimal job, relationship, and residential environment because they do not fully understand themselves, the plethora of available options, or how to match effectively. The result is forfeited happiness, health, and effectiveness for individuals, societies, and humanity.

Energy, Information, Individuals, Environments, and Goals

In this concluding section, we aim to cogently synthesize the research findings and theory presented in this book. We are deliberately concise in our description; the rest of the book provides the details and nuance. Ultimately, we use the findings presented in this volume to formulate an explanation of why you are.

Many studies have examined differences between people’s traits and how those differences are correlated, and yet the fundamental reasons why such differences and correlations occur has remained a mystery. Even large-scale investigations using advanced neuroimaging and molecular genetics reveal only narrow, intermediary mechanisms like brain area activation and allele expression.

Integrating concepts from economics, genetics, psychology, biology, and other fields, we synthesized thousands of meta-analyses to propose a theory that explains why some traits co-occur in individuals more often. In the process, we also elucidated why traits like high aggression, high anxiety, and low intelligence persist and why such diversity is valuable in human populations. While other theories emphasize the importance of the individual or the environment, we posit that no trait or environment is inherently good or bad on its own.2 Instead, such evaluations depend on the fit of the individual with the environment and the fit of both with the goals of the individual. These fits define fitness. That is, fitness is how well the characteristics of the individual combine with the demands of their environment to achieve goals.3 Fitness manifests across life domains as mental well-being, professional effectiveness, educational attainment, and longevity.

Individual differences are tuning parameters. These parameters make individuals more/less likely to set, pursue, and achieve various goals when presented with varying environmental constraints and resources. These parameters also determine how the individual weighs risk vs. reward, values freedom and order, approaches intrapersonal and social relations, balances desire for power with corresponding resource constraints, and approaches other fundamental dimensions of life. The world, especially the future, is too complex to be optimized with a singular solution.4 This is true of physical characteristics (e.g., our species’ ability to achieve goals is more resilient when some people are tall and others are short). This is also true of psychological characteristics: individuals embody unique constellations of traits that represent bets for what will be most effective in the environments they encounter. Casting diverse bets ensures the durability of species.5 In fact, our adversaries and those we view as the antitheses of ourselves may be our greatest partners in ensuring the achievement of long-term goals (e.g., survival of our kin).

We go further by highlighting how the agility to adapt oneself and goals to various environments is a common thread of effective individuals, which is why traits like cognitive ability predict success across so many disparate domains (e.g., work, creative pursuits, health). Nevertheless, we maintain that even rigid trait constellations can be successful when fit with the right goals and environment. Such views are consistent with the largest meta-analyses of two of the most important domains of psychological differences: personality and cognitive ability.

We proposed Cybernetic Trait Complexes Theory (CTCT) to describe why certain traits are correlated. The term “cybernetic” denotes goal-directed systems that self-regulate via feedback. Individuals are cybernetic systems that must prioritize finite resources among competing goals and strategies. Individuals set goals, detect their current state and movement toward goal states, consider their options, can take action to try to advance toward their goal state, and iteratively adjust their behaviors and goals based on evaluative feedback loops.6 This process (depicted in Figure 18 in Chapter 6) encapsulates goals, strategies, and behaviors that reflect the values, interests, abilities, personality, history, and environment of the individual.

Personality traits reflect different cybernetic preferences for sensing, evaluating, and behaving (i.e., typical strategies for assigning meaning and values to internal and external stimuli). Cognitive abilities index how effectively information is leveraged to set goals and employ strategies that maximize the probability of goal achievement (i.e., how efficiently, proficiently, and successfully goals are set, and pursued). Essentially, the universe is full of entropy, which is to say full of information, and more intelligent brains are better able to decipher and leverage this information to employ strategies and behaviors that increase the probability of goal attainment.7

Constellations of these traits and others, including values, interests, and physical attributes, form strategies aimed at maximizing odds of surviving and thriving. That is, personality traits and cognitive abilities jointly direct resource prioritization to achieve self-preservation and self-evolution. In the process, people invest energy in strategies distributed across two fundamental axes: homeostasis versus change and self/internal focus versus environment/external focus (see Chapter 6’s Figure 19). These strategies are reflected in trait complexes. Complexes emphasizing homeostasis enable strategies focused on psychological stability and maintaining the individual across environments. Complexes emphasizing change enable strategies focused on growth and activation for adaptation. Individuals can display different complexes at different times, but the probability of each complex differs across individuals due to their genetic blueprint and life histories.8

Successful achievement of goals hinges on employing appropriate strategies to cull and weigh information about oneself and one’s context to decide when/what/how/where to preserve and when/what/how/where to evolve. That is, when to persevere and when to pivot. In addition to sensory perception and processing, feedback loops are the key mechanism providing this information, and they make cybernetic systems inherently adaptive.

Life is a constant interplay of diversification and concentration, ebb and flow, change and stability, where the odds of an individual surviving and thriving are maximized through the adaptive orchestration of energy to prioritize growth and homeostasis in environmentally sensitive ways. Similarly, the odds of species survival are maximized by diversifying individuals’ predispositions toward certain strategies and their corresponding trait complexes to meet a wide range of environments. To fully understand human behavior and outcomes it is important not only to understand and measure the individual’s traits and outcomes but also what contexts best fit different trait constellations and goals. People are not types; instead, they manifest complex constellations of tuning parameters. A person might navigate by one constellation today and another tomorrow.9 Different levels of each parameter can be differentially valuable in different environments. Diversity makes us more resilient as a group, but at the same time it is important to acknowledge that some constellations are more likely to succeed in certain environments. Currently, comprehensive measures of the environment, taxonomies of goals, and studies of person-environment-goal fit are almost completely absent from the scientific literature, which is leading to misunderstandings about what traits predict success, why diversity is important, and what methods are most effective for changing behavior.

The current research proposes that success is a matter of effectively setting, pursuing, and attaining goals, and that this depends on the fit between the resources and constraints of the environment as well as the trait parameters of the individual. The current research also reinforces the proposal of DeYoung and Krueger (2018) that psychopathology ensues from malfunctioning cybernetic feedback loops (e.g., poorly set or pursued goals) as well as from mismatches between the trait parameters of the individual, their goals, and/or their environment. Finally, the current results indicate that traits bundle together to form optimal strategies for certain types of environments. Since these trait bundles are likely to be bounded by evolution and genetics and hence, by biology, the best way to increase the effectiveness of behaviors may actually be to help individuals set better-fitting goals and choose or create more suitable environments. After all, our choices are how we anchor and sail.

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