Intellectual similarity of virtual twin pairs: Developmental trends

Virtual twins (VTs) are same-age unrelated siblings reared together from infancy who replicate twinship, but without the genetic relatedness. A 2005 report from the ongoing Fullerton Virtual Twin Study found an IQ intraclass correlation of .26 (p < .01, n = 113 pairs) and a within-pair difference of 13.22 IQ points. The average age of VTs in that study was 8.10 years (SD = 8.56, range: 4.01-54.84 years). An opportunity to retest members of 43 VT pairs, 1.70-8.96 years after their time 1 assessment, allowed additional analyses of genetic and environmental influences underlying general intellectual development. A decrease in the VT IQ correlation and an increase in the within-pair difference were indicated, consistent with increasing genetic and/or non-shared environmental influences and decreasing shared environmental influence on general intellectual development throughout childhood.     

Cognitive competencies and aggressive behavior: A developmental study

A number of studies have demonstrated that increased socially related cognitive skills are associated with decreases in aggressive behavior. However, the link between aggression and intelligence or academic skills is less evident. While some research indicates that poor academic performance is related to aggression, it is unclear which components of intellectual ability and performance are critical to the management of aggressive behaviors. In two independent longitudinal studies of elementary school-age children, the relationship among several aspects of cognitive competence and several aspects of aggressive behavior were examined. The results of the first study showed that aggressive behavior observed in kindergarten children was more closely related to academic performance in the first and second grades than to general cognitive ability (IQ). The results of the second study, a comprehensive three-year investigation of upper elementary school-age children, indicated that teachers' assessments of aggression and parents' ratings of cruelty were consistent over time for boys, but not for girls. The intercorrelations among aggression measures within each of the three years also revealed stable sex differences. Boys identified as aggressive in the classroom were more likely to be perceived as aggressive, cruel, and/or delinquent at home, but for girls, there was little correlation between aggression at school and in the home. The analyses relating measures of cognitive functioning to indices of aggressive behavior made clear the importance of discriminating among various facets of these psychological constructs. IQ had a negligible relationship with aggression and a weak inverse relationship to delinquency. An overall index of cognitive functioning was a somewhat more consistent negative correlate of aggression, cruelty, and delinquency, especially for boys. A similar pattern was found for the correlates of academic performance. Academic disability was strongly related to delinquency in boys, and to a lesser degree to aggression in boys. Of the several cognitively related factors that were explored, Low Need Achievement manifested the strongest and most consistent relationships with the different facets of aggression and antisocial behavior, especially in boys. The implications of these results for psychological interventions in the school are discussed.     

Gender-Typed Behavioral Examples of Histrionic Personality Disorder

Findings that clinicians diagnose Histrionic Personality Disorder more frequently in women may be due to the feminine gender weighting of the criteria or because the diagnostic label elicits a feminine stereotype. Using a method derived from the act-frequency approach, undergraduates generated behavioral examples of the DSM-IIIR and DSM-IV Histrionic criteria without regard to sex or according to sex role instructions that elicited masculine or feminine sex roles. A national sample of psychologists and psychiatrists rated the representativeness of the symptoms for the Histrionic criteria or for Histrionic Personality Disorder. Feminine behaviors were rated more representative of Histrionic Personality Disorder and somewhat more representative of the Histrionic criteria than masculine behaviors suggesting that the feminine sex role is more strongly associated with the label than the criteria. Masculine behaviors were also rated less representative than sex-unspecified examples. Results provide a possible explanation for the higher rates of diagnosis of Histrionic Personality Disorder in women.     

Malingering,Perceptions of Illness,and Compensation Seeking in Whiplash Injury: A Comparison of Illness Beliefs Between Individuals in Simulated Compensation Scenarios and Litigation Claimants1

This paper compares beliefs about whiplash injury between individuals in simulated compensation/no compensation scenarios and actual litigant claimants. Comparisons between simulators and the clinical sample revealed that chronic patients reported significantly more symptoms than all simulator groups. The beliefs of the real compensation claimants in the acute phase of the condition were similar to those in the ‘injury only’ simulator group. The analyses identified a trend towards beliefs in the expected timeline of the illness becoming more negative with time, whilst feelings of control over the symptoms improve. The paper discusses indicators of malingering behavior and the possible involvement of litigation and treatment processes in the transition to a chronic state of ill health.