Julie Aitken Harris

A FURTHER EVALUATION OF THE AGGRESSION QUESTIONNAIRE: ISSUES OF VALIDITY AND RELIABILITY

An analysis of the four scales from Buss and Perrys (1992, Journal of Personality and Social Psychology, 63, 452-459) Aggression Questionnaire was conducted. Examined was the internal consistency, test-retest reliability, the influence of social desirability, and the interrelationships with other measures of aggression. The results suggest that the four scales of The Aggression Questionnaire have moderate to high internal consistencies and are stable over seven months of testing. Social desirability was found to have a moderately high negative relationship with the aggression scales suggesting that social desirability may influence responses provided on The Aggression Questionnaire. In addition, the four aggression scales were found to be positively related to other measures of aggression including scales assessing affect instability and aggressive attitudes, as well as scales designed for clinical use, suggesting some degree of construct validity.

The heritability of testosterone: A study of Dutch adolescent twins and their parents

The heritability of total plasma testosterone levels, determined from blood samples, was examined in 160 adolescent twin pairs and their parents. Subjects were tested as part of a larger study of cardiovascular risk factors, conducted in Amsterdam. Each subject provided a sample of blood which was assayed to measure testosterone concentrations. Correlations of testosterone in monozygotic twins were higher than in dizygotic twins. No resemblance was found between testosterone values in fathers and those in their children and a moderate correlation was seen between mothers and their daughters. The lack of resemblance between family members of opposite sex suggests that different genetic factors influence plasma testosterone concentrations in men and women. In adolescent men, approximately 60% of the variance in testosterone levels is heritable. The lack of father–son resemblance suggests that different genetic factors may be expressed in adolescence and adulthood. In women, 40% of the variance in testosterone levels is heritable, both in adolescence and in adulthood.

Measured intelligence, achievement, openness to experience, and creativity.

Are personality traits related to intelligence? This question is addressed in an in-depth examination of the correlations between, and factor structure of, measured intelligence and personality scales chosen to measure the dimensions of Openness and need for Achievement. Participants (203 adult men and 201 adult women) completed four scales of a timed, group administered, intelligence test, 10 personality scales, and a creativity measure. After principal components analysis with direct oblimin rotation, the two personality factors, Openness and Achievement, were found to have small to moderate positive correlations with an intelligence factor (which included the creativity scale), suggesting that intelligence is related to these personality trait dimensions.

Confirmatory factor analysis of The Aggression Questionnaire

A confirmatory factor analysis of the factor structure of The Aggression Questionnaire created by Buss and Perry (1992) [Journal of Personality and Social Psychology, 63, 452-459] was conducted to assess whether the scales purported 4 factors emerged. The results generally supported the 4-factor model. However, the hostility factor may be improved if 2 items pertaining to suspicion are removed from the scale. These items had relatively low loadings on that factor and decreased the hostility scales internal reliability.

An Evaluation of the Job Stress Questionnaire with a Sample of Entrepreneurs

A modified version of Caplans Job Stress Questionnaire (JSQ) was administered to 169 male and 56 female entrepreneurs. Entrepreneurs were found to have higher levels of stress associated with workload than with role ambiguity and underutilization of skills. Compared to scores reported previously for various occupational categories, the entrepreneurs scored significantly higher than did white collar, blue collar, and professional groups on the workload scale and significantly lower on scales measuring role ambiguity and under-utilization of skills. These results may be due to the nature of entrepreneurial activity, which is often characterized by heavy workloads, long hours, and a self-established role in the organization. Additionally, the factorial composition of the JSQ and its internal consistency were examined. Evidence of convergent and discriminant validity at the item and subscale level confirmed the a priori dimensions of the JSQ, although the internal consistency of the scales were low to moderate. The need for various improvements in the measurement of occupational stress is briefly discussed.

Environmental predictors of personality differences: A twin and sibling study.

Nonshared environmental influences have consistently been shown to account for at least as much of the variance in personality as genetic factors, but the nature of these nonshared influences has largely remained unidentified. To identify environmental predictors of differential personality development, the Personality Research Form and 4 measures of peoples perceptions of their background environments were administered to 143 adult twin pairs (93 monozygotic [MZ] and 50 dizygotic [DZ] and 66 pairs of same-sex nontwin (NT) siblings. Differences between MZ twins, DZ twins, and NT siblings in a number of dimensions of personality were significantly related to differences on the environmental measures, and phenotypic correlations between the personality and environment measures were themselves entirely attributable to correlated nonshared environmental effects.

Nature vs nurture: are leaders born or made? A behavior genetic investigation of leadership style.

With the recent resurgence in popularity of trait theories of leadership, it is timely to consider the genetic determination of the multiple factors comprising the leadership construct. Individual differences in personality traits have been found to be moderately to highly heritable, and so it follows that if there are reliable personality trait differences between leaders and non-leaders, then there may be a heritable component to these individual differences. Despite this connection between leadership and personality traits, however, there are no studies of the genetic basis of leadership using modern behavior genetic methodology. The present study proposes to address the lack of research in this area by examining the heritability of leadership style, as measured by self-report psychometric inventories. The Multifactor Leadership Questionnaire (MLQ), the Leadership Ability Evaluation, and the Adjective Checklist were completed by 247 adult twin pairs (183 monozygotic and 64 same-sex dizygotic). Results indicated that most of the leadership dimensions examined in this study are heritable, as are two higher level factors (resembling transactional and transformational leadership) derived from an obliquely rotated principal components factors analysis of the MLQ. Univariate analyses suggested that 48% of the variance in transactional leadership may be explained by additive heritability, and 59% of the variance in transformational leadership may be explained by non-additive (dominance) heritability. Multivariate analyses indicated that most of the variables studied shared substantial genetic covariance, suggesting a large overlap in the underlying genes responsible for the leadership dimensions.

Individual differences in multiple dimensions of aggression: a univariate and multivariate genetic analysis

Previous behaviour genetic studies of aggression have yielded inconsistent results: reported heritabilities for different types of aggressive behaviour ranging from 0 to 0.98. In the present study, 247 adult twin pairs (183 MZ pairs; 64 same-sex DZ pairs) were administered seven self-report questionnaires which yielded 18 measures of aggression. Univariate genetic analyses showed moderate to high heritabilities for 14 of these 18 measures and for a general aggression factor and three correlated aggression factors extracted from the measures. Multivariate genetic analyses showed sizeable genetic correlations between the different dimensions of aggression. Thus, individual differences in many types of aggressive behaviour are attributable to some extent to genetic factors and there is considerable overlap between the genes that operate on different types of aggressive behaviour.

Review and methodological considerations in research on testosterone and aggression

The present paper reviews studies investigating the possible correlation between testosterone and aggression. First, methodological considerations in testosterone research are outlined. These considerations are used as a basis on which past studies are reviewed. How testosterone is related to various personality dimensions is then discussed, concluding with how testosterone is related to aggression in non-criminal and criminal samples. The paper concludes with the suggestion that testosterone may have a relationship with sexually dimorphic behaviors, in particular aggression.

Genetic and environmental contributions to individual differences in alcohol expectancies

Abstract One hundred and seventy-six pairs of adult twins (115 MZ pairs, 61 same-sex DZ pairs) completed the Alcohol Effects Questionnaire: a 42-item measure of how people expect to feel following alcohol consumption (e.g. tense/relaxed, clumsy/coordinated, daring/cautious). Item factor analysis yielded nine factors, accounting for 60% of the variance, which were interpreted as representing the expectancies: impaired, happy/secure, sociable, restless, antisocial, aggressive, sensation-seeking, emotional and fearless. A three-factor solution was also fitted to the data, yielding factors interpreted as happy/secure, impaired and activated. Univariate genetic analyses revealed that all but the impairment factors had a significant, though moderate, genetic component. The remaining non-genetic variance for all but one factor was entirely attributable to nonshared environmental factors. The results support previous studies in the area of alcohol use, indicating that some proportion (up to 45%) of the variance in several expectancies concerning alcohol use is attributable to genetic factors.