Part-list cuing of associative chains: tests of strategy disruption

Three experiments assess the veracity of the strategy disruption explanation of part-list cuing impairment. Experiment 1 demonstrated no mnemonic detriment in recall as a result of significant disruption of the participants' self-selected forward associative seriation retrieval strategy. Experiment 2 replicated Experiment 1 while reducing overall performance levels in an attempt to reveal any possible detrimental effects. Experiment 3 ruled out 2 possible alternative explanations by demonstrating the typical part-list cuing impairment within this experimental context. It is concluded that the results challenge a strict version of the strategy disruption hypothesis.     

Bimanual curvature discrimination of hand-sized surfaces placed at different positions

This study explores bimanual curvature discrimination of cylindrically curved, hand-sized surfaces. The setup was designed so that the postures of the observers' left and right arms and hands were thesame as if the observers were holding a large object in their hands. We measured psychometric curves for observers who used active, dynamic touch; these curvatures ranged from 1.18 to 4.05/m. Bimanual discrimination thresholds were found to be between 0.26 and 0.38/m on average; they were in the same range as unimanual thresholds reported in previous studies. Variation of (1) the horizontal distance between the stimuli or (2) the position of the setup had no effect on thresholds. In addition, we found that a number of observers showed discrimination biases in which they judged two physically different curvatures to be equal. Biases were of the same order of magnitude as the thresholds and could be either positive or negative. These biases can possibly be explained by small differences in left and right arm movements, an explanation that is supported by the position dependence of biases for individual observers.     

Academic performance,popularity, and depression predict adolescent substance use

Eighty-nine high school seniors completed a questionnaire on their feelings and activities, including their use of drugs. Adolescents with a low grade point average, high popularity, and high depression were more likely to smoke cigarettes, drink alcohol, and smoke marijuana than were their peers. Cigarette and alcohol use predicted marijuana use, which in turn predicted cocaine use.     

Recency effects as a window to generalization: separating decisional and perceptual sequential effects in category learning

Accounts of learning and generalization typically focus on factors related to lasting changes in representation (i.e., long-term memory). The authors present evidence that shorter term effects also play a critical role in determining performance and that these recency effects can be subdivided into perceptual and decisional components. Experimental results based on a probabilistic category structure show that the previous stimulus exerts a contrastive effect on the current percept (perceptual recency) and that responses are biased toward or away from the previous feedback, depending on the similarity between successive stimuli (decisional recency). A method for assessing these recency effects is presented that clarifies open questions regarding stimulus generalization and perceptual contrast effects in categorization and in other domains.     

Symptom-based subfactors of DSM-defined conduct disorder: evidence for etiologic distinctions

Past research investigating the structure of conduct disorder (CD) symptoms has provided evidence of a phenotypic distinction between aggressive and rule-breaking subfactors of CD. However, evidence of etiologic distinctions between these subfactors has not been reported to date. In the current study, the authors investigated this issue in a sample of 1,151 male twins who were 17 years of age. The results indicate that aggressive and rule-breaking CD subfactors have both common and distinct etiologic influences, with shared environmental influences playing a significant role in rule-breaking behaviors. The authors discuss implications of these findings for the assessment and treatment of CD.     

Genetic and environmental influences on religiousness: findings for retrospective and current religiousness ratings

Estimates of the degree of genetic and environmental influences on religiousness have varied widely. This variation may, in part, be due to age differences in the samples under study. To investigate the heritability of religiousness and possible age changes in this estimate, both current and retrospective religiousness were assessed by self-report in a sample of adult male twins (169 MZ pairs and 104 DZ pairs, mean age of 33 years). Retrospective reports of religiousness showed little correlation difference between MZ (r=.69) and DZ (r=.59) twins. Reports of current religiousness, however, did show larger MZ (r=.62) than DZ (r=.42) similarity. Biometric analysis of the two religiousness ratings revealed that genetic factors were significantly weaker (12% vs. 44%) and shared environmental factors were significantly stronger (56% vs. 18%) in adolescence compared to adulthood. Analysis of internal and external religiousness subscales of the total score revealed similar results. These findings support the hypothesis that the heritability of religiousness increases from adolescence to adulthood.     

Etiologic connections among substance dependence,antisocial behavior,and personality: modeling the externalizing spectrum

A hierarchical biometric model is presented of the origins of comorbidity among substance dependence, antisocial behavior, and a disinhibited personality style. The model posits a spectrum of personality and psychopathology, united by an externalizing factor linked to each phenotype within the spectrum, as well as specific factors that account for distinctions among phenotypes within the spectrum. This model fit self-report and mother-report data from 1,048 male and female 17-year-old twins. The variance of the externalizing factor was mostly genetic, but both genetic and environmental factors accounted for distinctions among phenotypes within the spectrum. These results reconcile evidence for general and specific causal factors within the externalizing spectrum and offer the externalizing factor as a novel target for future research.     

The effects of the Triple P-Positive Parenting Program on preschool children with co-occurring disruptive behavior and attentional/hyperactive difficulties

Two variants of a behavioral family intervention (BFI) program known as Triple P were compared using 87 preschoolers with co-occurring disruptive behavior and attentional/hyperactive difficulties. Families were randomly allocated to enhanced BFI (EBFI), standard BFI (SBFI), or a waitlist (WL) control group. At postintervention both BFI programs were associated with significantly lower levels of parent-reported child behavior problems, lower levels of dysfunctional parenting, and greater parental competence than the WL condition. The EBFI condition was also associated with significantly less observed child negative behavior in comparison to the WL. The gains achieved at postintervention were maintained at 1-year follow-up. Contrary to predictions, the enhanced program was not shown to be superior to the standard program using any of the outcome measures at either postintervention or follow-up. Each of the programs produced significant reductions in children's co-occurring disruptive behavior and attentional/hyperactive difficulties with 80% of the children showing clinically reliable improvement in observed negative behavior from preintervention to follow-up.