| Research |
A Psychobiological Framework for Personality Neuroscience The topic of my research is the structure and sources of human personality. By "structure," I mean primarily the basic elements or traits that make up personality. Psychometric research has demonstrated that five broad domains (the "Big Five") can be used to organize most aspects of personality: Neuroticism (negative emotion, anxiety, vulnerability, irritability) Agreeableness (altruism, empathy, cooperation, politeness) Conscientiousness (organization, industriousness, diligence, constraint) Extraversion (positive emotion, enthusiasm, sociability, assertiveness) Openness/Intellect (imagination, intelligence, curiosity, creativity) Theoretically, most stable observable individual differences in cognition, emotion, motivation, and behavior fall into one of these five domains or can be described in terms of a combination of two or more of them. How do individual differences in brain function produce individual differences in personality? The Big Five model has great potential for integrating the vast amount of existing research on individual differences and for organizing the emerging field of personality neuroscience. Personality measures generate a large collection of intercorrelated trait variables; the brain is a large collection of interacting neural systems. My long-term goal is to map traits onto their sources in the ongoing functioning of the brain, using techniques including neuroimaging and molecular genetics. Additionally, I am working on a theory that not only specifies the psychological and biological functions underlying personality traits but also describes them as integrated and interacting elements of an adaptive system. Current Research Projects 1. A Hierarchical Model of Personality Based on the Big Five Personality traits can be categorized by arranging them into a hierarchy, based on their correlations with each other. Broad domains (e.g., Extraversion), each encompassing many related traits, are located near the top of the hierarchy, and very specific patterns of behavior and experience (e.g., talking a lot) are located near the bottom. More specific traits that group together within a more general trait are assumed to share underlying sources that are reflected by the more general trait (though the fact that they are differentiated at the more specific level implies that they do not share all of their sources). I have been working to identify both higher- and lower-level traits in the hierarchy, relative to the Big Five. The resulting organization is depicted here. [Related publictions] Higher-Order Factors of the Big Five: Stability and Plasticity The Big Five were originally thought to be the most general level of personality description. However, they proved to be consistently related to each other in a way that indicates two higher-order factors or metatraits. The first of these combines Emotional Stability (the opposite of Neuroticism), Agreeableness, and Conscientiousness. The second combines Extraversion and Openness/Intellect. We have interpreted the first of these as a broad Stability factor and the second as a Plasticity or exploration factor. Stability and Plasticity represent the manifestation in personality of the two broadest requirements of any human being: 1. the need to maintain a stable psychosocial organization to achieve various goals, and 2. the need to incorporate novel information into that organization, as the situation of the individual changes both internally and externally. The primacy of these needs reflects the one universal problem of all living things, namely uncertainty – unpredictable change, novelty, anomaly, the unexpected, the unknown; it is this problem that renders stability a challenge and plasticity advantageous. Similar concepts of stability and plasticity can be usefully applied to understanding phenomena as varied as societies and neurons, but I am most interested in their particular manifestation in personality. We have hypothesized that Stability is linked to the neurotransmitter serotonin and that Plasticity is linked to dopamine. Between Facets and Domains: Ten Aspects of the Big Five A behavior-genetic study has demonstrated that two genetically-based factors underlie the shared variance of the six facet scales that make up each of the Big Five personality domains in the popular NEO Personality Inventory – Revised (Jang, Livesley, Angleitner, Riemann, & Vernon, 2002). We have found similar factors in analyses of even larger numbers of facets. These findings indicate the presence of two distinct (but correlated) factors, or aspects, within each Big Five domain, representing an intermediate level of personality structure between facets and domains. We have constructed a 100-item measure of these ten aspects of the Big Five, called the Big Five Aspect Scales (BFAS), which has been validated in two large samples. The BFAS provides a measure of the Big Five, each broken down into two aspects, which are more parsimonious than the facets but more specific than the domains, and which appear to have distinct genetic substrates. We are optimistic about its potential utility for personality neuroscience. The BFAS is in the public domain. Please use it! [Formatted versions of the BFAS for self ratings and for peer ratings] 2. Openness/Intellect and Cognitive Abilities I am attempting to develop a neuropsychological model of the trait of Openness/Intellect. I am interested in a variety of higher cognitive functions that fall within the purview of Openness/Intellect (such as intelligence, insight, reasoning, divergent thinking, working memory, and learning) and that allow individuals to be cognitively flexible and creative. 3. Externalizing Behavior Externalizing behavior covers a range of often problematic behaviors, including impulsivity, aggression, hyperactivity, antisocial behavior, and drug abuse. I am interested in how externalizing behavior relates to individual differences in personality and cognition and their underlying biological substrates. In other words, what are the sources of externalizing behavior and its related processes? We found that externalizing behavior is related to low Stability and high Plasticity, plus low intelligence. Additionally, I have been utilizing molecular genetics to investigate externalizing behavior. As knowledge of the human genome expands exponentially, so do the opportunities for linking personality traits to genetic processes. Variations in genes that code for elements of the brain's diffuse neuromodulatory systems (serotonin, dopamine, norepinephrine, acetylcholine) offer a promising avenue for detecting significant genetic influences on phenotypic personality. My research on externalizing behavior currently focuses on genes that influence the functions of dopamine in the prefrontal cortex, including the dopamine D4 receptor gene (DRD4) and catechol-O-methyltransferase (COMT). We found that DRD4 variation influences the manner in which externalizing behavior is associated with cognitive impairments. Past Research Projects 1. Types and Processes of Self-Deception I have been involved in research carried out by my graduate advisor, Jordan Peterson, on individual differences in self-deception. We conceive of self-deception as failure to explore subjective evidence that one's plans or beliefs are in error. I have been particularly interested in the difference between the two types of self-deception found in factor analyses of questionnaires designed to measure bias. The first type is overconfidence or egoism, the second is conformity or moralism. It appears that these seemingly very different traits share something important, namely a rigid devotion to one's current plans and beliefs, regardless of whether these stem from within (egoism) or from an external moral system (conformity). 2. Individual Differences in Responses to Information Technology In the information age, computers and the internet are increasingly part of our everyday lives, but they also constitute an extremely complex technological system that must be mastered by a species that certainly didn’t evolve in the company of computers. I am interested generally in the ways in which people respond to novel complexity of any kind. I am interested specifically in whether differences in responses to information technology have any effect on psychological assessment, which increasingly takes place on computers. With Ian Spence, I have developed a new instrument, the Technology Profile Inventory (TPI), to measure a wide range of attitudes toward information technology. Contact me or Ian Spence if you would like a copy of the most up to date version of the TPI. [Back to Homepage ... Back to Top] |