Chapter 8

Cross-Cutting Trends in Our Results

CHAPTER SUMMARY

1. Our expansive database and deeply-grounded taxonomies of personality and intelligence generated over 3,500 meta-analyses of the links between these domains. Most links have never been meta-analyzed previously and most of those that have shifted considerably.
2. Distinguishing constructs by level (e.g., aspect, facet, dimension, sub-dimension) matters since nomological networks are not always isomorphic.
3. Personality and cognitive ability are not independent domains, and they are likely connected by several neurobiological, chemical, and developmental pathways shaped by evolution and immediate environments.
4. Personality traits and cognitive abilities form fitness-based, functional trait complexes vital to human life. These complexes are defining features of the self-sustaining systems for setting, progressing toward, and achieving or revising goals via the coordinated use of resources.
5. Both personality traits and cognitive abilities contribute to strategies for surviving and thriving in varying environments.

As noted in Chapter 7, the results of our meta-analyses highlight three conclusions that cut across traits and abilities: (1) personality and cognitive ability are typically considered independent domains, but they are not; (2) distinguishing constructs by level (e.g., aspect, facet, dimension, sub-dimension) matters since nomological networks are not always isomorphic; and (3) personality traits and cognitive abilities form fitness-based, functional trait complexes vital to human life: having self-sustaining systems for setting, progressing toward, and achieving or revising goals via the coordinated use of resources. This chapter summarizes key evidence supporting each of these cross-cutting conclusions.

Co-Variation: Much More Than Openness, and Stronger Than Negligible

Personality and cognitive ability are not independent domains, although they are typically considered as such. The prevailing view is that only traits relating to intellectual openness (e.g., need for cognition, curiosity) are related to cognitive abilities (von Stumm & Ackerman, 2013). Indeed, sizable openness-abilities relations were also evident in our findings (see Chapter 5’s Figure 16 and Supplementary Tables 256–272 in Appendix I of the online supplementary materials for detailed results). However, there were many other traits with relations as sizable.1 In fact, 347 relations with non-openness traits displayed correlations of .20 or larger with cognitive abilities, which are medium-to-large relations in psychological research (Funder & Ozer, 2019). Three prime contributors to this pattern are noted below. Complete technical results for these traits are in Supplementary Tables 201, 204, 210, 225, and 244 in Appendix I (see also Figure 24 for a depiction of major examples).

First, individuals higher on neuroticism-related traits tend to score lower on most cognitive abilities. Figure 24a depicts many neuroticism-related traits’ (e.g., uneven tempered, depression, withdrawal, test anxiety, suspiciousness) sizable, negative relations with many non-invested cognitive abilities. These findings suggest that neuroticism-related traits are enervating. For example, neuroticism’s depression facet is a notable, negative correlate of visual processing and fluid ability (p̂ = -.32 and -.17, respectively). Self-regulating and -sustaining processes, including cognitive performance on tests or in life, may be disrupted among those high on depression. Alternatively, these findings may reflect the neuroticism-inducing effects of low cognitive ability (e.g., impaired cognitive strategies for regulating emotions). In the context of Cybernetic Trait Complexes Theory (CTCT), the high depression, high psychological withdrawal, and lower cognitive ability trait complex corresponds to the organism’s energy-saving setting, which would confer a survival advantage for the individual in resource-scarce environments. These findings are discussed at greater length in Chapter 7 when we describe trait complexes that contribute to homeostasis and, more specifically, promote internal stability.

Second, the activity facet of extraversion represents a contrasting example that has sizable, positive relations with several non-invested primary abilities, specifically long term memory storage and retrieval, visual processing, and processing abilities (see Figure 24b). Individuals who are active and energetic also tend to have higher levels of these abilities. Given these associations, it is not surprising that activity is also positively and robustly related to acquired knowledge abilities. In the context of CTCT, the high activity, processing ability, and long term memory trait complex corresponds to the organism’s high-performance/energy setting, which would be advantageous for the individual in resource-rich environments.

Third, there are many personality traits that show sizable correlations with acquired cognitive abilities (see Figure 24c and Supplementary Tables 49–80 in Appendix G for complete technical results). Three specific traits’ relations are depicted for illustration: conscientiousness’ industriousness aspect and agreeableness’ compassion aspect are appreciably related to several sub-dimensions of knowledge acquisition. A similar example is order’s relevance to the acquisition of verbally-based knowledge. These sizable acquired knowledge -industriousness, -order, and -compassion clusters may reflect multifaceted adaptations corresponding to persistent, systematic, and humanitarian knowledge acquisition pathways, respectively.

Figure 24. Examples of non-openness personality traits with sizable relations with cognitive abilities. 24a. Neuroticism-related traits’ relations with non-invested abilities. 24b. Activity facet of extraversion’s relations with non-invested abilities. 24c. Compassion aspect of agreeableness and conscientiousness-related traits’ relations with invested abilities. Y-axes indicate p̂ values.

In sum, even though openness has notable associations with many cognitive abilities (see Supplementary Tables 256–272 in Appendix I), consistent with previous research (Anglim et al., 2022; von Stumm & Ackerman, 2013), the findings depicted in Figure 24 illustrate some of the many other personality traits that display significant relations. Theoretically, these complexes can be interpreted as trait-ability bundles that confer unique psychological fitness advantages and drawbacks.

Complete relations between cognitive ability and personality are visualized in Figure 25 and can be further explored in Figure 26 as well as with the interactive webtool. These figures further illustrate that most personality traits show sizable relations with cognitive abilities. Within the abilities domain, relations are typically stronger for acquired knowledge abilities, highlighting specific pathways of knowledge acquisition. For the personality domain, in addition to openness, many traits drawing variance from neuroticism, conscientiousness, and extraversion factors have noteworthy relations to both non-invested and acquired cognitive abilities.

Figure 25. Cognitive ability-personality relations.

Note. Cognitive abilities are depicted in the left hemisphere and personality traits are shown in the right. Label formatting and color shading differentiates traits at different levels of the Stanek and Ones (2018) personality and ability hierarchies. Links between traits depict meta-analytically estimated effect sizes corrected for unreliability. Link widths reflect absolute magnitude of effect size. Links are only shown for robustly estimated relations that had N ≥ 1,000 or K ≥ 10. An interactive version of this figure can be viewed at http://stanek.workpsy.ch/interactivewebtool/

Figure 26. Cognitive ability-compound personality trait relations.

Note. Cognitive ability constructs are depicted in the left hemisphere and compound personality traits are shown in the right. Label formatting and color shading differentiates constructs at different levels of the Stanek and Ones (2018)’s Unified Cattell-Horn-Carroll abilities hierarchy and Pan-Hierarchical Five Factor Model. Links between traits depict meta-analytically estimated effect sizes corrected for unreliability. Link widths reflect absolute magnitude of effect size. Links are only shown for robustly estimated relations that had N ≥ 1,000 or K ≥ 10. An interactive version of this figure can be viewed at http://stanek.workpsy.chinteractivewebtool-compoundpersonalitytraits

Differential Relations by Construct Level

Previous research has suggested that sub-traits within each major Big Five personality factor are rooted in disparate biological mechanisms (DeYoung et al., 2007, 2009, 2012). Distinguishing personality trait hierarchy levels (e.g., factors, aspects, and facets) when examining relations with cognitive abilities helped identify differential relations with cognitive abilities. For example, conscientiousness’ industriousness aspect was more strongly related to cognitive abilities than the global conscientiousness factor. Openness and agreeableness’ aspects each displayed similarly unique relations, as described in Chapter 5.

Distinguishing cognitive ability hierarchy levels was useful as well. An illustrative example is neuroticism’s depression facet. Depression displays stronger, negative relations with many cognitive ability constructs compared with the withdrawal aspect it is part of (see Figure 24a above). Conscientiousness-related traits evidence similar trends. The global conscientiousness factor has the weakest relations with cognitive abilities (mean2 p̂ = .01). However, its industriousness aspect is a more potent, positive correlate of cognitive abilities, including all acquired knowledge dimensions (mean p̂ = .25). See Figure 27a for a visualization and Supplementary Tables 224–226 in Appendix I for complete, detailed results.

Figure 27. Personality aspects’ differential relations with cognitive abilities. 27a. Conscientiousness aspects’ relations with non-invested and invested abilities. 27b. Agreeableness aspects’ relations with non-invested and invested abilities. 27c. Openness aspects’ relations with non-invested and invested abilities. Y-axes indicate p̂ values.

Similarly, some meso-level aspects within personality factors have differing, and sometimes even opposing, relations with some major cognitive ability domains. Agreeableness’ compassion and politeness aspects, conscientiousness’ industriousness and orderliness aspects, and openness’ intellect and experiencing aspects all differ meaningfully in their relations with cognitive abilities. See Figure 27 for major aspect divergences and Supplementary Tables 210– 211, 225–226, and 257–258 in Appendix I for complete, detailed results. The disparate nomological networks of these aspects of the Big Five personality factors were foreshadowed by the work of DeYoung and colleagues (2007, 2009, 2012), who posited that aspect distinctions may be rooted in biology, especially for openness’ intellect and experiencing aspects. For example, from a functional perspective, the overarching openness factor reflects a predisposition for acquiring and using information (e.g., via data and/or experience [Connelly, Ones, & Chernyshenko, 2014]). Its intellect aspect may build capacity for adaptation to the environment through development and growth achieved by collecting and evaluating data rationally and logically, whereas its experiencing aspect may be adaptive for self-enrichment through collecting and evaluating information using one’s senses.

Openness’ intellect aspect and its aligned facets, such as need for cognition and ideas, are positively related to retrieval fluency abilities, visual processing abilities, and fluid abilities, including the deductive components (i.e., general sequential reasoning and quantitative reasoning; mean p̂ = .16; see Supplementary Tables 258–260 in Appendix I for complete, detailed results). Individuals with greater non-invested mental abilities may find cognitive engagement more rewarding or at least less aversive. Unsurprisingly, the intellect aspect and its aligned facets are also strong, positive correlates of acquired knowledge constructs (mean p̂ = .28). However, relations are stronger for verbal abilities than quantitative abilities (mean p̂ = .30 and .22, respectively). Intellect and related facets may function as an activating force for pursuing and acquiring verbal abilities, conferring fitness in adapting to external, often social, environments.

The experiencing aspect of openness may also play a role in knowledge acquisition, as evidenced by positive, far from negligible relations with both quantitative and verbal acquired knowledge (mean p̂ = .17 and .28, respectively; see Supplementary Table 257 in Appendix I). This may reflect a motivational drive for individuals to explore and engage with the world through their senses to self-enrich and develop. Alternatively, acquisition of knowledge may have collateral benefits in developing characteristic adaptations related to experiencing. For example, persistent exposure to cognitive stimulation encountered during knowledge acquisition may help develop cognitive pliability that strengthens tendencies toward aesthetics, fantasy, and the like (see Supplementary Tables 257–266 in Appendix I for all openness aspect and facet results).

Complexes of Traits Indicating Fitness Strategies: Self-Preservation and Self-Evolution

The current quantitative synthesis investigated the overlap between two vast and consequential domains of human individual differences—cognitive ability and personality. By reviewing and meta-analyzing over 60,000 relations between the full range of cognitive abilities and personality traits from virtually all accessible published and unpublished research from the past 100 years, we were able to discern psychologically functional relations that highlight trait complexes for self-preservation and self-evolution. These complexes serve the function of maintaining psychological homeostasis (i.e., stability) and/or enabling change (i.e., development and growth). The tensile strength that results from this dichotomy strengthens individuals, social groups, and humankind; it’s where freedom meets security. The result is a stable and well-tested dynamic that preserves unity while driving progress.3

Contrary to what is commonly believed by behavioral scientists and lay people, human cognitive abilities and personality traits are intrinsically and intricately related. Cognitive ability-personality bonds documented in this research highlight clusters of abilities and personality traits involved in psychological fitness. These complexes represent key packages of individual differences that were shaped by evolutionary environments to form strategies tuned to address the fundamental goals of maintaining homeostasis and enabling change internally and externally. Each individual can be viewed as a bet, a set of tuning parameter values meant to maximize fitness and increase the probability of surviving and flourishing in an ever-changing environment. Cognitive ability-personality relations documented in this research expose these complexes.

Strengths of the Current Research

Others before us have examined some of these relations to varying degrees using primary studies as well as meta-analyses, but the present work differs from those efforts in terms of the (a) expansiveness of its database, (b) breadth, depth, and empirical grounding of the personality and cognitive ability taxonomies used, and (c) extent of brand new personality-ability links meta-analytically quantified. These strengths afford insights that are relevant to scholars and practitioners across fields.

The current investigation’s expansive database contained more than 24 times as many contributing effect sizes and 12 times as many participants as the largest previous meta-analysis of personality and cognitive ability (Anglim et al., 2022). Our data characterize more than two million individuals across more than 50 countries, represent a broad range of ages from 12 to over 100, and are nearly perfectly balanced by sex. The database we are making available offers a foundation to guide future research.

Secondly, the results of the current meta-analyses are reported at a more granular level than previous works. Such granular resolution was enabled by advancing taxonomic knowledge of personality and cognitive ability constructs. For example, evidence clarifying personality facets emerged in the past decade and a half for each Big Five factor: conscientiousness (Roberts et al., 2004, 2005), openness (Connelly, Ones, Davies, et al., 2014; Woo et al., 2014), extraversion (Davies, 2012; Wilmot et al., 2019), agreeableness (Davies, 2012; Ones et al., 2020), and neuroticism (Birkland & Ones, 2006; DeYoung et al., 2007). Likewise, the general factor of personality, meta-traits, and aspects were mostly unrecognized until Musek (2007), Digman (1997), van der Linden et al. (2017), and DeYoung et al.’s (2006) recent works. The use of a comprehensive, evidence-based taxonomy and compendium of associated measures enabled (1) the investigation of more personality constructs than all previous meta-analyses combined, including 28 additional personality constructs, and (2) recognition of theoretically meaningful patterns in the results (e.g., consideration of the hierarchical nature of personality traits).

Similarly, the use of the updated, unified Cattell-Horn-Carroll (CHC) taxonomy (Stanek & Ones, 2018) for cognitive abilities is also a major strength. Previous meta-analyses in this domain have also used the CHC in organizing their cognitive ability constructs. However, those analyses have not distinguished between specific abilities contained within each primary ability dimension, due to a lack of data or the assumption that they would similarly relate to personality constructs. We have examined relations with abilities at different levels of the cognitive abilities hierarchy: general mental ability, primary abilities, and specific abilities (McGrew, 2009a, 2009b, p. 10). We were also careful to distinguish between learning efficiency and retrieval fluency as distinct primary abilities, as well as non-invested and invested abilities, uncovering distinct personality correlates of each. Using taxonomically grounded cognitive ability dimensions enabled us to report on 84 more ability constructs and consider the hierarchical nature of cognitive ability to a greater degree than previous works. The meta-analytic findings for these cognitive ability constructs represent fresh conclusions and novel discoveries.

In all, of the 3,543 personality-cognitive ability construct relations, 3,310 had not been examined in previously published meta-analyses (Ackerman & Heggestad, 1997; von Stumm & Ackerman, 2013; Wolf & Ackerman, 2005; Anglim et al., 2022), and only 233 were directly comparable to previously published meta-analytic estimates. In nearly half of these comparable meta-analyses, effect sizes shifted by .10 or more correlational points; in 22% of comparisons (52 analyses), the change was .15 points or more. In sum, based on these directly comparable analyses, nearly half of the conclusions drawn from previous research merited revision based on the large-scale data presented in the current set of results.

In conclusion, both personality traits and cognitive abilities contribute to strategies for surviving and thriving in varying environments. Such individual differences help direct resources toward cybernetic activities and, ultimately, self-preservation and self-evolution. Like an anchor, cognitive abilities and personality traits for homeostasis confer stability and help maintain the individual across environments. Like a sail, cognitive abilities and personality traits for change underpin activation for adaptation as well as growth. Personality traits reflect strategies for sensing, evaluating, and behaving. Cognitive abilities explain how efficiently and proficiently goals are set, pursued, and achieved in complex environments. Clusters of personality traits and cognitive abilities coordinate the use of finite resources toward goal achievement as well as the generation of new goals, interpretations, and strategies as goals are attained or obstructed. Personality and cognitive ability domains are inseparably related, likely through several neurobiological, chemical, and environmental pathways. Many avenues beckon for further exploration. This book highlights important co-dependencies between these two fundamental domains of individual differences by providing the most comprehensive empirical review of cognitive ability-personality bonds. The fine resolution provided by the thousands of individual meta-analyses presented here provides encyclopedic quantification of their relations and affords a macro perspective on psychological fitness. The extensive data presented here deepen understanding of human psychological differences and pave the way for improved theoretical explanations of human behavior and applications for harnessing human potential and improving the human condition.

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