"Nothing to see here": No structural brain differences as a function of the Big Five personality traits from a systematic review and meta-analysis

Abstract

Personality reflects social, affective, and cognitive predispositions that emerge from genetic and environmental influences. Contemporary personality theories conceptualize a Big Five Model of personality based on the traits of neuroticism, extraversion, agreeableness, conscientiousness, and openness to experience. Starting around the turn of the millennium, neuroimaging studies began to investigate functional and structural brain features associated with these traits. Here, we present the first study to systematically evaluate the entire published literature of the association between the Big Five traits and three different measures of brain structure. Qualitative results were highly heterogeneous, and a quantitative meta-analysis did not produce any replicable results. The present study provides a comprehensive evaluation of the literature and its limitations, including sample heterogeneity, Big Five personality instruments, structural image data acquisition, processing, and analytic strategies, and the heterogeneous nature of personality and brain structures. We propose to rethink the biological basis of personality traits and identify ways in which the field of personality neuroscience can be strengthened in its methodological rigor and replicability.

Keywords: Brain structure; Five-factor model; Meta-analysis; Personality; Systematic review.

Figure 1.

Flowchart of Gray Matter Volume Literature Search and Selection of Eligible Studies. The Flowchart was modified from Liberati et al. (2009).

Figure 2.

Flowchart of Cortical Thickness Literature Search and Selection of Eligible Studies. The Flowchart was modified from Liberati et al. (2009).

Figure 3.

Flowchart of Surface Area Literature Search and Selection of Eligible Studies. The Flowchart was modified from Liberati et al. (2009).

Figure 4.

Sample Mean Age and Age Range Distribution of Studies Included in the Systematic Review and Meta-analysis across Big Five Personality Traits and Three Brain Indices. Note. The study (y-axis) was ordered by the mean age (dot) from each study. Studies were separately labeled as “(hc)/(pt)/(hc/pt)” indicating results from the given study were reported separately for healthy and patient groups or combining healthy and patient groups. Not all studies provided the information for mean age or age range, thus, data from those studies were presented incompletely or not presented. Two red dashed vertical lines indicating the age of 18 and 65