King’s Research Portal DOI: 10.1016/j.paid.2016.04.009 Document Version Publisher's PDF, also known as Version of record Link to publication record in King's Research Portal Citation for published version (APA): Mitchell, R. L. C., & Kumari, V. (2016). Hans Eysenck’s interface between the brain and personality: Modern evidence on the cognitive neuroscience of personality. Personality and Individual Differences, 74-81. https://doi.org/10.1016/j.paid.2016.04.009 Citing this paper Please note that where the full-text provided on King's Research Portal is the Author Accepted Manuscript or Post-Print version this may differ from the final Published version. If citing, it is advised that you check and use the publisher's definitive version for pagination, volume/issue, and date of publication details. And where the final published version is provided on the Research Portal, if citing you are again advised to check the publisher's website for any subsequent corrections. 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Sep. 2021 Personality and Individual Differences 103 (2016) 74–81 Contents lists available at ScienceDirect Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid Hans Eysenck's interface between the brain and personality: Modern evidence on the cognitive neuroscience of personality Rachel L.C. Mitchell a,⁎, Veena Kumari b,c a Centre for Affective Disorders, Institute of Psychiatry Psychology & Neuroscience, King's College London, London, UK b Department of Psychology, Institute of Psychiatry Psychology & Neuroscience, King's College London, London, UK c NIHR Biomedical Research Centre for Mental Health, South London and Maudsley NHS Foundation Trust, London, UK article info abstract Article history: In this review, incorporating functional and structural MRI and DTI, with evidence gathered over the last 15 years, Received 12 January 2016 we examine the neural underpinnings of extraversion and neuroticism, the two major personality dimensions in Accepted 1 April 2016 Eysenck's (1967) biological model of personality. We present clear evidence that, as proposed by Eysenck nearly half-a-century ago, these traits relate meaningfully to the functioning and structure of various cortical and limbic Keywords: brain regions. Specifically, there is a robust relationship between neuroticism and the functioning of several emo- Personality traits tion processing networks in the brain, particularly during exposure to negative stimuli. The brain regions show- Neuroticism Extraversion ing this association include a number of cortical regions implicated in emotion regulation, depression and Emotion perception anxiety, in addition to many sub-cortical/limbic regions. Currently, there are few studies directly assessing the re- Cognition lationship between extraversion and the cortical arousal system in the context of varying stimulations but data available so far are remarkably consistent with Eysenck's model. Future neuroimaging studies guided by relevant personality and cognitive theories, and with sufficient power to allow application of sophisticated analysis methods (for example, machine learning) are now needed to improve our understanding of the biological basis of individual differences and its application in the promotion of well-being and mental health. © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). 1. Introduction Experience, Agreeableness & Conscientiousness). There is a reasonable correspondence between the two models for extraversion and neuroti- Well before the advent of modern human brain imaging, Hans cism (Costa & McCrae, 1995). We have also considered findings relating Eysenck, the visionary psychologist and the most influential personality to the remaining three factors of the five-factor model as well as those researcher in recent history, proposed a theory (Eysenck, 1967) that relating to psychoticism, the third dimension in Eysenck's revised went beyond description and measurement of personality and, for the model (Eysenck & Eysenck, 1975), were examined within the same first time, provided the neurophysiological causes of personality. It study, for completeness. was unique in trying to explain extraversion and neuroticism, the two major personality dimensions in Eysenck's model (the third dimension, 2. fMRI evidence psychoticism, added formally later in 1975), in terms of individual dif- ferences in the functioning of aspects of the central nervous system 2.1. Cognitive processing (Eysenck, 1967). Here, we review neuroimaging evidence, gathered mainly over the last 15 years, examining the association between extra- Eysenck's theory proposed that the extraversion–introversion dimen- version and/or neuroticism and brain activation/connectivity patterns sion (extraversion = positive affectivity, marked by pronounced engage- elicited by a wide range of cognitive and affective tasks. We have includ- ment with the external world and characterized by high sociability, ed relevant functional magnetic resonance imaging (MRI), structural talkativeness, energy and assertiveness) is caused by variability in cortical MRI and diffusion tensor imaging (DTI) studies generated in the context arousal (Eysenck, 1967). Those who score low for extraversion (intro- of Eysenck's three-factor factor model as well as Costa and McCrae's verts) have lower response thresholds and are consequently more corti- five-factor personality model (Neuroticism, Extraversion, Openness to cally aroused than those who score high for extraversion (extraverts). It further postulated an inverted U-shaped relation between cognitive per- ⁎ Corresponding author at: Centre for Affective Disorders, (PO Box 72), Department of formance and ‘level of arousal’, jointly determined by environmental Psychological Medicine, Institute of Psychiatry Psychology & Neuroscience, King's fi College London, 16 De Crespigny Park, Denmark Hill, London SE5 8AF, UK. arousal potential (de ned in terms of a range of environmental manipu- E-mail address: [email protected] (R.L.C. Mitchell). lations and task parameters) and subject arousability as reflected in http://dx.doi.org/10.1016/j.paid.2016.04.009 0191-8869/© 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). R.L.C. Mitchell, V. Kumari / Personality and Individual Differences 103 (2016) 74–81 75 extraversion. These postulates jointly predict that, at low environmental given its known association with reaction time variability, no published arousal potential, extraverts' performance would be lower than that of in- study has yet examined the effect of neuroticism in moment-to- troverts'. As environmental arousal increases, performance of extraverts moment/trial-to-trial variability in brain activations. should improve and they should catch up with introverts; and, at high levels of environmental arousal, extraverts should out-perform introverts 2.2. Affect with a decline in introverts' performance, until it becomes so arousing as to evoke transmarginal inhibition (TMI) (Eysenck, 1994; Gray, 1964). One of the great challenges faced by the human mind is the need to With evocation of TMI, introverts may experience lower arousal incre- comprehend the content of other minds. Thus a rapidly increasing liter- ments than extraverts. There is considerable support for these predictions ature has sought to explore the psychological and neural mechanisms from behavioral studies (Eysenck, 1981). Eysenck's model further postu- behind “the mental operations that underlie social interactions, includ- lated that level of arousal, resulting from a combination of environmental ing perceiving, interpreting, and generating responses to the intentions, arousal and subject arousability, is mediated by activity in a ‘cortical dispositions, and behaviors of others” (Green et al., 2008), namely ‘so- arousal system’, modulated by reticulo-thalamic-cortical pathways cial cognition’. One of the most fundamental means we have of making (Eysenck, 1967, 1981). A circuit that seemingly corresponds to this corti- these inferences is the emotion cues that other people display. Howev- cal arousal system, including the dorsolateral prefrontal cortex (dlPFC) er, individual differences associated with personality traits are a key in- and anterior cingulate regions, has been identified in studies applying fluence on the way we perceive and respond to emotion cues (Britton, fMRI to a wide range of cognitive tasks (Duncan & Owen, 2000). Impor- Ho, Taylor, & Liberzon, 2007). Indeed, our personality, whether we tantly, findings of an fMRI study (Kumari, ffytche, Williams,