Preface

This is a book about personality and intelligence. Personality is what a person typically does, thinks, and feels. Intelligence is what a person is cognitively capable of. How are personality and intelligence related, and why? By shining a light on the intricate networks of traits and abilities, we aim to not only deepen our knowledge but also challenge prevailing conceptions of human individuality.

This book presents a landmark study of relations between personality traits and cognitive abilities. It is the most inclusive and in-depth empirical coverage of the topic. Our study synthesizes data from more than 1,300 studies conducted over the last century, involving over two million participants from 50 countries and a diverse array of cultures and demographic groups. It embraces the power of meta-analysis—a methodological tool that combines results from multiple studies into a harmonized chorus of scientific evidence. Meta-analysis not only provides a more reliable panorama of the relations between personality traits and cognitive abilities, but also paves the way for the synthesis of novel theories based on robust cumulative findings. By distilling the essence of many studies into a coherent narrative, we reveal patterns that might otherwise remain obscured in individual studies. This research is a testament to the transformative potential of a bird’s eye view on a mountain of data.

The chapters of this book do not need to be read in order. Rather, we recommend that readers orient themselves by reading the introduction provided in Chapter 1, then proceed according to their knowledge, aims, and interests. Chapter 2 provides necessary background for readers unfamiliar with contemporary hierarchical models of personality and cognitive abilities. Chapter 3 offers information about our methodology. Chapter 4 frames the results for researchers with greater interest in or knowledge of cognitive abilities. Chapter 5 frames the results for researchers with greater interest in or knowledge of personality. Chapters 6 and 7 are best read together, with the former presenting our theory and the latter providing a theoretical interpretation of the findings. Chapters 8 and 9 allow the reader to take stock of key patterns in the results and opportunities for future research. Chapter 10 aims to stimulate expansive thought and profound contemplation by offering an elucidation of what the results mean for science, individuals, and humanity as a whole.

This research represents the most monumental and meticulous work either one of us has ever undertaken. Beyond being just a research project, this work consumed our lives and recast our worldviews. We were stretched intellectually, physically, and psychologically in ways we never imagined. Through our journey of writing this book, we developed and changed. We gained a deeper understanding of ourselves, deciphered foundational intricacies of human psychology, and, we believe, unveiled fundamental phenomena about how the universe operates.

Our journey started almost 14 years ago, with an ambition to conduct an unparalleled study of two of the most defining domains of individuality: personality traits and cognitive abilities. After examining the available large-scale studies and meta-analyses, we realized that a sweeping set of meta-analyses was needed to examine the full spectrum of personality-ability connections. On the personality side, many aspects and facets of well-known personality traits, such as the Big Five, as well as higher order and compound traits, had never been previously meta-analyzed. The same was true for many overlooked primary and specific abilities. After unearthing dozens, then hundreds, then thousands of primary studies, the project grew into Kevin’s dissertation under Deniz’ mentorship. Yet even a 1,000+ page dissertation (Stanek, 2014) was just a stepping stone to understanding the grander pattern of connections.

Our next step was to revisit how we were grouping traits and measures. Doing this accurately and reliably was critical to avoiding the jingle jangle jungle (Kelley, 1927) that has splintered so much psychological research on individual differences. We therefore spent nearly four years getting the taxonomic organization of personality traits and abilities right, reflecting contemporary consensus about these domains’ hierarchical structures. As importantly, we compiled a compendium of measures for each domain, indicating which traits or abilities are assessed by each measure (Stanek & Ones, 2018; see also Chapter 3 and Appendices A–E of this book). Although we knew that our personality compendium converged well with existing large-scale, multi-inventory analyses and previous personality taxonomies and compendia (e.g., Barrick & Mount, 1991; Credé et al., 2010; Hough & Ones, 2002), further evidence was needed to support our abilities compendium. Fortunately, Kostal (2019) devoted a large portion of his dissertation to validating our compendium, finding good convergent and divergent validity for our ability clusters. In this volume, we examine these well-understood and well-documented 79 personality traits and 97 cognitive abilities that range from the broad, such as general intelligence and extraversion, to the specific, such as reading speed and assertiveness.

Next, we updated our 2014 analyses, which clearly indicated that there were personality aspects and facets beyond openness that had meaningful relations with various non-invested and invested abilities. Accordingly, we prepared a summary of our findings for publication, circulating it to our immediate intellectual family. Their useful and insightful comments helped us further hone the content. However, one comment raised a pivotal question: Can you explain why or how these personality-ability relations emerge? Without such an explanation, our work would be incomplete.

Our initial instinct was to search for existing theories that could adequately explain the findings. Existing theories indeed offered some explanations for the personality-ability connections we observed. For instance, the theory of self-regulation suggests that certain personality traits, like conscientiousness, may enhance cognitive performance by improving focus and effort regulation. Similarly, skill acquisition theories propose that traits like openness to experience can facilitate learning and thereby enhance cognitive abilities. But each theory only explained part of the picture. We spent almost two years examining theories, eventually poking holes in all of them. Each theory seemed too limited to one domain (e.g., knowledge acquisition) or field (e.g., psychology).

A more comprehensive, elemental theory that spoke to fields beyond psychology, while explaining the patterns of relations revealed in our expansive meta-analyses, was needed. We synthesized Cybernetic Trait Complexes Theory (CTCT; see Chapter 6) as an elegant theoretical account that explains our findings as well as other related observations from fields as diverse as neuroscience, economics, biology, military science, and genetics. Chapter 7 illustrates how thousands of our findings can be accounted for by this single theory, which forms the foundation of our ultimate conclusions about why personality and ability are related.

After writing up our detailed results and theoretical account, the resulting manuscript was too large to fit in any refereed journal. We also needed to reach readers across disciplines. Therefore, we opted to publish a summary of our meta-analytic findings in the Proceedings of National Academy of Sciences (Stanek & Ones, 2023), with this book as a companion. Here we describe the full results, lay out our theory, and interpret the findings through that lens. The rich details and descriptions provided in this book offer the reader a deeper understanding of personality-ability relations and why they exist. This volume’s significance extends beyond the scientific discoveries described, encompassing the intricate, meaningful patterns that have emerged from our findings.

In the enterprise of scientific exploration, bold propositions are likely to raise both eyebrows and objections. However, any work that hopes to be groundbreaking must disrupt accepted wisdoms. We anticipate that some may question the ambitious scope of our meta-analytic approach, the personality traits and abilities we studied, or even some fundamental assumptions that underpin our research. We do not claim infallibility, and we firmly believe that diligent empirical inquiry, voluminous and comprehensive data, and rigorous analysis, as well as open debate, will deepen understanding of the complex interconnections of personality and ability. Our study is but a milestone in this ongoing journey.

We hope our contribution will inspire, provoke thought, and fuel further inquiry into the grand tapestry of human nature. Above all, we want this book to serve as a foundation for applications that maximize and enhance human potential. Could it help career advisors to tailor advice with greater precision? Educators to design programs that resonate with each unique personality-ability profile? Clinicians to pinpoint personalized therapies? Organizations and individuals to find their perfect fit? We believe it can, and that such practical applications will enhance people’s lives in meaningful ways.

Deciphering the architecture of personality-intelligence relations not only unlocks scientific insights and practical applications, but also reveals deep-rooted, profound patterns in human diversity. With this book, we set the stage for understanding and utilizing the fascinating interplay between who we are and why we are. Just as ecosystems are built from a diversity of species, each playing their part in the symphony of life, so too does this work seek to embrace the complexity and diversity of human nature. We invite you to journey with us into this rich landscape, to challenge the assumptions of the known, and to explore the vast uncharted terrain of human individuality.

References

Barrick, M. R., & Mount, M. K. (1991). The Big Five personality dimensions and job performance: A meta-analysis. Personnel Psychology, 44(1), 1–26.

Credé, M., Roch, S. G., & Kieszczynka, U. M. (2010). Class Attendance in College A Meta-Analytic Review of the Relationship of Class Attendance With Grades and Student Characteristics. Review of Educational Research, 80(2), 272–295.

Hough, L. M., & Ones, D. S. (2002). The structure, measurement, validity, and use of personality variables in industrial, work, and organizational psychology. In Handbook of industrial, work, and organizational psychology (Vol. 1, pp. 233–277). Sage.

Kelley, T. L. (1927). Interpretation of educational measurements. World Book Co. http://psycnet.apa.org/psycinfo/1928-00533-000

Kostal, J. W. (2019). Human cognitive abilities: The structure and predictive power of group factors. [Unpublished doctoral dissertation]. University of Minnesota-Twin Cities.

Stanek, K. C. (2014). Meta-Analyses of Personality and Cognitive Ability [Doctoral dissertation, University of Minnesota-Twin Cities]. https://hdl.handle.net/11299/201107

Stanek, K. C., & Ones, D. S. (2018). Taxonomies and compendia of cognitive ability and personality constructs and measures relevant to industrial, work and organizational psychology. In D. S. Ones, C. Anderson, C. Viswesvaran, & H. K. Sinangil (Eds.), The SAGE handbook of industrial, work & organizational psychology: Personnel psychology and employee performance (pp. 366–407). Sage.

Stanek, K. C., & Ones, D. S. (2023). Meta-analytic relations between personality and cognitive ability. Proceedings of the National Academy of Sciences, 123(23). https://doi.org/10.1073/pnas.2212794120