A dynamic extraversion model. The brain's response to a single dose of a stimulant drug

The aim of this paper is to present a mathematical dynamic modelling of the effect a stimulant drug has on different people which, at the same time, can be a useful tool for future brain studies. To this end, a dynamic model of the evolution of extraversion (considering its tonic and phasic aspects) has been constructed taking into account the unique personality trait theory and the general modelling methodology. This model consists of a delayed differential equation which, on one hand, considers that the active stimulus, a consequence of a single intake, is not constant; on the other hand, it contemplates that the state variable representing the phasic extraversion also represents the brain activation. The derivative of this state variable is calculated as the sum of the homeostatic control flow, the excitatory effect flow and the inhibitor effect flow. The solutions of this equation relate the tonic activation of an individual (that characterizes his or her personality) with his or her phasic activation level, whose evolution over time describes the organism's response to a single drug intake. These solutions quantitatively reproduce the predictions of current personality theories and anticipate vulnerability to drug misuse and addiction development.     

Dynamics of the general factor of personality in response to a single dose of caffeine

General Factor of Personality (GFP) research is an emergent field in personality research. This paper uses a theoretical mathematical model to predict the short-term effects of a dose of a stimulant drug on GFP and reports the results of an experiment showing how caffeine achieves this. This study considers the General Factor of Personality Questionnaire (GFPQ) a good psychometric approach to assess GFP. The GFP dynamic mechanism of change is based on the Unique Trait Personality Theory (UTPT). This theory proposes the existence of GFP which occupies the apex of the hierarchy of personality, and extends from an impulsiveness-and-aggressiveness pole (approach tendency) to an anxiety-and-introversion pole (avoidance tendency). An experiment with 25 volunteers was performed. All the participants completed the GFPQ and the Sensation-Seeking Scale list of adjectives from the trait version of MAACL-R (Multiple Affect Adjective Checklist Revised) on an empty stomach. The participants in the experimental group (20) received 330 mg of caffeine. All the participants filled in a state version form with the sensation-seeking adjectives every 4.5 minutes. This study considers that the Sensation-Seeking Scale list of adjectives from the MAACL-R, available in both trait and state versions, is a good psychometric approach to assess GFP. The results show that GFP is modified by a single dose of caffeine in the direction predicted by the UTPT.     

I need my smartphone: A hierarchical model of personality and cell-phone addiction

Using a comprehensive personality model, this study is the first to examine the relationship between a full range of personality traits and cell phone addiction. 346 college students completed an online survey that asked respondents to complete measures of the Big-Five personality traits and measures of materialism and need for arousal, Barratt’s (1959) impulsiveness scale, and a four-item measure of cell phone addiction. Data were analyzed using structural equation modeling. Couched in Mowen’s (2000) 3M Hierarchical Model of Personality, the elemental traits of emotional instability and materialism were positively associated while introversion was negatively associated with cell phone addiction. The central trait of attention impulsiveness exhibited a direct and positive association with cell phone addiction. A significant negative relationship between conscientiousness and all three dimensions of Barratt’s impulsiveness scale (central trait) was found. Several additional relationships between the elemental traits of Mowen’s personality hierarchy and the three dimensions of impulsiveness (central trait) also were uncovered. Study implications and future research directions are discussed.     

Changing the general factor of personality and the c-fos gene expression with methylphenidate and self-regulation therapy

A deepening in the biological nature of the general factor of personality (GFP) is suggested: the activation level of the stress system is here represented by the gene expression of c-fos. The results of a single case experimental design are reported. A model of four coupled differential equations that explains the human personality dynamics as a consequence of a single stimulant drug intake has been fitted to psychological and biological experimental data. The stimulant-drug conditioning and its adaptation to the considered mathematical model is also studied for both kinds of measures. The dynamics of the c-fos expression presents a similar pattern to the dynamics of the psychological measures of personality assessed by the GFP-FAS (Five-Adjective Scale of the General Factor of Personality) as a consequence of a single dose of stimulant drug (methylphenidate). The model predicts similar dynamic patterns for both psychological and biological measures. This study proves that describing mathematically the dynamics of the effects of a stimulant drug as well as the effects of a conditioning method on psychological or subjective variables and on gene expression is possible. It verifies the existence of biological mechanisms underlying the dynamics of the General Factor of Personality (GFP).     

Trait Extraversion and Dopamine Function

An influential theory within personality neuroscience suggests that trait extraversion is underpinned by individual differences in dopamine function. In a review of the relevant literature, we evaluate this theory in light of the evidence from molecular genetics, neuroimaging, and psychopharmacology. Evidence linking individual differences in extraversion with dopamine‐relevant genes, structural volume of dopamine‐rich brain regions (e.g., in striatal and ventral prefrontal areas), dopamine receptor availability, and frontal alpha asymmetry is mixed at best. Evidence concerning both scalp recorded (electroencephalogram) and hemodynamic (functional magnetic resonance imaging) neural responses to rewards appears somewhat more promising. Perhaps the best evidence concerns extraversion‐dependent responses – both neural and behavioural – to dopaminergic drugs. Future research in this area must go beyond the demonstration of theoretically consistent associations and attempt to provide more specific causal evidence for the dopamine hypothesis of extraversion. A further challenge is to expand this hypothesis to incorporate other neurobiological processes that are likely to underlie this trait.     

Validating a new method for quantifying traits: The computer-administered visual analog

This article introduces a new method for assessing personality traits that uses graphic rather than written items to facilitate the convergent validation of personality traits. A computer-administered visual analog procedure is presented that samples 40 equally spaced positions along a trait continuum five times. Examinees initiate each trial by pressing the space bar and end it by pressing either a “True” or “False” key indicating if that location describes them or not. Response time is measured in milliseconds. The majority answer determines the aggregate response and the median response time determines the latency for the aggregate response to each location on the trait continuum. This procedure enables an empirical measure of trait variability. Results indicated theoretically meaningful responses in 94 college students on each of two personality dimensions; extraversion and trait anxiety. The predicted inverted-U function was obtained for both personality dimensions such that the fastest response times were associated with 0 and 5 “True” responses, somewhat longer response times were associated with 1 and 4 “True” responses, and the longest times were associated with 2 or 3 “True” responses. Statistically significant and substantial validity coefficients were obtained with the Eysenck personality inventory extraversion scale, and the state-trait anxiety inventory, form Y-2.     

Personality characteristics of opiate addicts

18 Ss dependent on opiate drugs completed three personality trait questionnaires, and were compared with 18 controls matched for demographic variables. The drug dependent sample were significantly higher than controls in psychoticism, but lower in extraversion and telic dominance. No difference between the groups was found in locus of control. These data are compared with existing research.     

The dynamic role of personality States in mediating the relationship between extraversion and positive affect

One of the most noteworthy and robust findings in personality psychology is the relationship between extraversion and positive affect. Existing theories have debated the origins and nature of this relationship, offering both structural/fixed and environmental/dynamic explanations. We tested the novel and straightforward dynamic hypothesis that part of the reason trait extraversion predicts trait positive affect is through an increased propensity to enact extraverted states, which in turn leads to experiencing more positive affect states. We report 5 experience sampling studies (and a meta‐analysis of primary studies) conducted in natural environments and laboratory settings in which undergraduate participants (N = 241) provided ratings of trait extraversion, trait positive affect, extraversion states, and positive affect states. Results of primary studies and the meta‐analysis showed that relationships between trait extraversion and trait positive affect were partially mediated by aggregated extraversion states and aggregated positive affect states. The results supported our dynamic hypothesis and suggested that dynamic explanations of the relationship between trait extraversion and trait positive affect are compatible with structural explanations. An important implication of these findings is that individuals might be able to increase their happiness by self‐regulating their extraverted states.     

Consumer Personality and Coping: Testing Rival Theories of Process

This research examines the effect of consumer dispositions on the relationships between stress‐related appraisals, consumption emotions, and the coping process. We comparatively tested rival models of these relationships. Our data show that the consumer personality traits of consumer assertiveness and marketing maven and the general personality trait of extraversion interact with cognitive appraisals to influence consumers’ choice of coping strategies. The research contributes to existing knowledge of how these consumer personality traits motivate consumer behavior, and it enriches existing models of the relationship between personality influences and coping.     

Child Personality as Moderator of Outcome in a School‐based Intervention for Preventing Externalising Behaviour

Studying moderators of intervention effects is essential to elucidate what works for whom. The present study investigated whether child personality moderates short‐term and follow‐up effects of an individualised preventive school‐based intervention for children with externalising behaviour. The sample consisted of 48 schools, with 264 fourth‐grade children displaying externalising behaviour (M_age = 10.2 years), randomly assigned to the intervention (n = 191) or no intervention control (n = 73) condition. Teachers and children reported at pretest, posttest and follow‐up test about reactive and proactive aggression. Child personality was assessed by teachers at pretest. Child conscientiousness moderated short‐term intervention effects, indicating that more organised and planful children benefited more from the intervention. Child extraversion moderated both short‐term and follow‐up intervention effects, with low extraverted children showing larger effects. These results affirm the importance of including personality as moderator of intervention effects in future studies, as interventions adapted to specific child traits might yield larger effects. Copyright © 2012 John Wiley & Sons, Ltd.     

The relationship between lottery ticket and scratch‐card buying behaviour,personality and other compulsive behaviours

The study examines how demographics, other forms of compulsive behaviour and personality are related to the buying frequency and compulsiveness in lottery tickets and scratch‐cards. An integrative framework is developed and tested in a sample of respondents. Results indicated that the buying compulsivenesses in lottery tickets and scratch‐cards have the same correlates. The buying compulsivenesses in both lottery tickets and scratch‐cards were found to be positively related to cigarette consumption and the extraversion dimension of personality and negatively related to the agreeableness and intellect dimensions of personality. Copyright © 2002 Stewart Publications Ltd.     

Health-related behaviour and personality trait development in adulthood

This investigation explored the contribution of a healthy lifestyle to personality trait stability and change during adulthood. A nationally representative sample of 11,133 Australian adults completed self-report measures of health-related behaviour and personality traits at baseline (2010) and again four years later (2014). Results showed that physical activity and alcohol intake, and to a lesser extent diet and cigarette smoking, were important for mean-level change and intra-individual stability of personality for all trait dimensions. Moreover, positive health behaviours were associated with less of a decrease in extraversion and more of an increase in openness, agreeableness and conscientiousness over four years.These findings suggest that healthy living might help to facilitate desirable personality trait stability and change during adulthood.     

Extraversion and Agreeableness: Divergent Routes to Daily Satisfaction With Social Relationships

We examined the unique effects of extraversion and agreeableness (and honesty‐humility) on everyday satisfaction with family, friends, romantic life, and acquaintances, and explored potential mediators of these effects. Three diary studies (Ns = 206, 139, 185) were conducted on Singaporean university students. In Studies 1 and 2, participants rated their satisfaction with different relationship categories. In Study 3, participants rated their satisfaction and social interactions with 10 target individuals each day for a 1‐week period. Both extraversion and agreeableness predicted relationship satisfaction. However, the effect of extraversion was mediated by greater levels of trust in others, whereas the effect of agreeableness was mediated by less frequent negative exchanges (e.g., criticism, perceived anger, and perceived neglect). The effect of honesty‐humility on negative exchanges was similar to agreeableness. When both were entered as predictors, only the effect of honesty‐humility was significant. We discuss how the processes by which personality affect relationship satisfaction vary depending on the trait as well as the particular measure that is used (IPIP NEO PI‐R, California Q‐Set, and IPIP‐HEXACO).     

Personality Traits and Job Success: An investigation in a Thai sample1

The purpose of this study was to examine the predictive power of each facet of the five‐factor model of personality on job success in a Thai sample. The sample consisted of 2518 persons from seven occupations. The research found that for all occupational groups neuroticism was significantly negatively correlated with job success, while extraversion and conscientiousness were significantly positively correlated with job success. Moreover, conscientiousness was the only personality trait that consistently predicted job success of persons across occupations.     

Personality traits in patients with narcolepsy

Narcolepsy is a lifelong disorder with the main symptoms of sleep attacks and cataplexy. In this study 49 narcoleptic patients were investigated with a battery of personality inventories, covering the following personality dimensions: anxiety-neuroticism, extraversion and socialization. The results were compared with three groups: normal subject, psychiatric inpatients with anxiety and outpatients with psychosomatic complaints. The main aim was to evaluate a clinical impression of a high degree of extraversion in narcoleptic patients, which according to Eysenck's model could be related to a disturbance in the arousal regulation. Narcoleptic patients had higher anxiety-neuroticism scores than normal individuals, particularly in terms of Somatic Anxiety. They had unexpectedly low scores in some socialization scales, and were contrary to our hypothesis slightly lower in the extraversion variables, than the comparison groups. The high scores in anxiety-neuroticism personality scales may depend on an anxiety-provoking effect of central stimulant drugs and/or a lability of the autonomic regulation associated with the disorder. Further, the strain caused by the narcoleptic symptoms may result in high scores in anxiety-neuroticism scales and low scores in socialization scales, via social-learning mechanisms. However, there may also be a coupling between the genetics of narcolepsy and biologically based personality traits.     

Testing an Adaptationist Theory of Trait Covariation: Relative Bargaining Power as a Common Calibrator of an Interpersonal Syndrome

This article provides the first test of an adaptationist ‘common calibration’ theory to explain the origins of trait covariation, which holds that (i) personality traits are often facultatively calibrated in response to cues that ancestrally predicted the reproductive payoffs of different trait levels and (ii) distinct traits that are calibrated on the basis of common input cues will exhibit consistent patterns of covariation. This theory is applied to explain the covariation within a ‘personality syndrome’ encompassing various interpersonal trait dimensions (e.g. extraversion, emotionality and attachment styles). Specifically, it is hypothesized that these traits are inter‐correlated because each is calibrated in response to relative bargaining power (RBP)—a joint function of one's ability to benefit others and harm others. Path analyses from a correlational study compellingly supported this theoretical model: Objective and self‐perceived measures of RBP‐enhancing phenotypic features (physical attractiveness and physical strength) influenced an internal regulatory variable indexing RBP (i.e. self‐perceived RBP), which in turn had robust effects on each of the focal personality traits. Moreover, in support of the theory's core postulate, controlling for self‐perceived RBP greatly reduced the covariation within the interpersonal syndrome. These novel findings illustrate the promise of an evolutionary psychological approach to elucidating trait covariation. Copyright © 2013 John Wiley & Sons, Ltd.     

Personality characteristics of smokers and ex-smokers

The present paper examines the relationship between personality and smoking status in a random sample of 1257 adults. A broad sample of personality constructs were assessed to cover the major dimensions of personality. These included the EPQ, MMPI MacAndrew and Ego Strength scales, the Vando augmenter-reducer scale, the trait subscale of the STAI and the Rosenberg self-esteem scale. Factor analysis suggested that trait anxiety, neuroticism, self-esteem and ego strength could be grouped into a construct analogous to Esysenck's notion of neuroticism. Extraversion, augmenting-reducing, and the MacAndrew scale were grouped into a construct called extraversion. Results showed that smokers were the most extraverted group. Gender differences in the relation between smoking and neuroticism were found. Male smokers were much more neurotic than non-smokers and men who quit smoking, whereas there were no group differences in neuroticism for women. Both male and female smokers were high on psychoticism.     

Applicant–Employee Fit in Personality: Testing predictions from similarity‐attraction theory and trait activation theory

We extend prior research by examining whether, and how, applicant–employee fit in the personality traits of conscientiousness, agreeableness, and extraversion affect organizational attractiveness. We test hypotheses based on similarity‐attraction theory and trait activation theory. Results from two studies indicate that applicants high in valued traits are more attracted to organizations when employees are more similar to them in those personality traits, whereas employees’ trait levels do not affect attraction for applicants low in valued traits. The effects of objective applicant–employee fit in personality on attractiveness were mediated by perceived applicant–employee fit. The pattern of the observed applicant–employee fit interactions was best predicted by trait activation theory and, thus, provide an important extension to similarity‐attraction theory.     

Resting Frontal EEG Asymmetry and Personality Traits: A Meta‐analysis

Frontal asymmetry has been widely used as a marker of emotion, motivation, and psychopathology. When assessed during the resting state, it is regarded as an index of trait approach and withdrawal motivation. However, the replicability of these associations with personality is currently unclear. The present meta‐analysis seeks to provide a comprehensive quantitative review of the relationship between personality traits and resting electroencephalographic (EEG) frontal asymmetry. We distinguished five personality clusters: extraversion, neuroticism, impulsivity, anger, and defensiveness. Data from 79 independent samples with overall 5700 participants were included in the meta‐analysis. The results revealed that less than 0.4% of the variance in extraversion and neuroticism could be explained by resting frontal asymmetry. Similarly, a small effect was observed for trait anger, and a small‐sized to medium‐sized effect was observed for defensiveness, although the number of studies was very low. No significant effect emerged for impulsivity. The effects were further reduced after adjustment for publication bias. Given some evidence for heterogeneity, sub‐traits were analysed, and methodological moderators were investigated. Based on the results, we conclude that the validity of resting frontal asymmetry as a marker for personality is not supported. Finally, recommendations are given to increase the replicability of frontal asymmetry research. © 2019 European Association of Personality Psychology