Different parameters support generalization and discrimination learning in Drosophila at the flight simulator

We have used a genetically tractable model system, the fruit fly Drosophila melanogaster to study the interdependence between sensory processing and associative processing on learning performance. We investigated the influence of variations in the physical and predictive properties of color stimuli in several different operant-conditioning procedures on the subsequent learning performance. These procedures included context and stimulus generalization as well as color, compound, and conditional discrimination (colors and patterns). A surprisingly complex dependence of the learning performance on the colors' physical and predictive properties emerged, which was clarified by taking into account the fly-subjective perception of the color stimuli. Based on estimates of the stimuli's color and brightness values, we propose that the different tasks are supported by different parameters of the color stimuli; generalization occurs only if the chromaticity is sufficiently similar, whereas discrimination learning relies on brightness differences.     

Effects of antisocial personality, cocaine and opioid dependence, and gender on eye movement control

Substance-dependent patients have been reported to exhibit abnormal smooth pursuit and saccadic eye movements. However, contrasts of the effects of different substances and the effects of comorbid psychiatric symptoms such as antisocial personality have rarely been performed. Separate analyses examined the effects of cocaine dependence, opioid dependence, or antisocial personality disorder. In each analysis, sex was included as an additional grouping factor. The dependent measures were the gain of smooth pursuit eye movement and the delay and accuracy of saccadic eye movement. Analyses of covariance indicated that both cocaine dependence and antisocial personality, but not opiate dependence, were associated with a significant reduction in gain of smooth pursuit eye movement. Cocaine dependence and antisocial personality also slowed the onset of saccadic eye movements, but only in men. No group differences were found in the accuracy of saccadic eye movements. The results suggest that the neurophysiological effects of cocaine dependence and antisocial personality overshadow the effects of heroin. The significance of these findings for visual attention and reading skill has yet to be assessed.     

The role of dopamine in reinforcement: changes in reinforcement sensitivity induced by D1-type, D2-type, and nonselective dopamine receptor agonists

Dose-dependent changes in sensitivity to reinforcement were found when rats were treated with low, moderate, and high doses of the partial dopamine D1-type receptor agonist SKF38393 and with the nonselective dopamine agonist apomorphine, but did not change when rats were treated with similar doses of the selective dopamine D2-type receptor agonist quinpirole. Estimates of bias did not differ significantly across exposure to SKF38393 or quinpirole, but did change significantly at the high dose of apomorphine. Estimates of goodness of fit (r2) did not change significantly during quinpirole exposure. Poor goodness of fit was obtained for the high doses of SKF38393 and apomorphine. Decrements in absolute rates of responding were observed at the high dose of quinpirole and at the moderate and high doses of SKF38393 and apomorphine. Changes in r2 and absolute responding may be due to increases in stereotyped behavior during SKF38393 and apomorphine exposure that, in contrast to quinpirole, were distant from the response lever. The present data provide evidence that sensitivity to reward is affected more strongly by dopamine D1-like receptors rather than D2-like receptors, consistent with evidence from other studies investigating consummatory dopamine behavior and the tonic/phasic dopamine hypothesis.     

Suicidality in African American men: the roles of southern residence, religiosity, and social support

The rise in suicide by African Americans in the United States is directly attributable to the dramatic, nearly three-fold increase in suicide rates of African American males. Gibbs (1997) hypothesized high social support, religiosity, and southern residence are protective factors against suicidality for Black people. This hypothesis was tested among 5,125 participants from the National Comorbidity Survey; 299 were African American males. In this study we hypothesized that there would be significantly lower suicidality in the South, and social support and religiosity would mediate this relationship. Our results indicate that Southern region is indeed a significant predictor of suicidal symptoms in African American men, such that suicidal symptoms were lower in the South, but religiosity and social support did not account for this effect. Other potential mediators were also examined.     

A cross-sectional evaluation of the factorial invariance of anxiety sensitivity in adolescents and young adults

This study examined the cross-sectional factorial invariance of anxiety sensitivity in an ethnically diverse sample of adolescents (n = 173; mean age 15.5 years) and young adults (n = 291; mean age 20.1 years). Research in adult and youth samples suggests that anxiety sensitivity is best understood as a hierarchical construct with several lower-order factors. Factor models based on previous research using both adult and youth samples were compared and a hierarchical model with three lower-order factors provided the best fit to the data. Results supported the hypothesis that the factor structure of the Anxiety Sensitivity Index was invariant across age and gender. The factor scores also demonstrated differential correlations with symptoms of anxiety and depression. Results are discussed with regard to construct validation and understanding the structure of anxiety sensitivity in youth.     

Psychopathic traits in adolescent offenders: an evaluation of criminal history, clinical, and psychosocial correlates

Although a large body of research has established the relevance of psychopathy to adult offenders, its relevance to adolescent offenders is far less clear. The current study evaluated the clinical, psychosocial and criminal correlates of psychopathic traits in a sample of 226 male and female incarcerated adolescent offenders. According to an 18-item version of the Psychopathy Checklist-Youth Version (PCL-YV; Forth, Kosson, & Hare, 2003), only 9.4% exhibited a high level of psychopathic traits (PCL-YV>/=25). Consistent with past research, higher PCL-YV scores were positively associated with self-reported delinquency and aggressive behavior and were unrelated to emotional difficulties. Although higher PCL-YV scores were associated with the experience of physical abuse, the only psychosocial factor to predict PCL-YV scores was a history of non-parental living arrangements (e.g. foster care). In terms of criminality, a violent/versatile criminal history was positively associated with psychopathic traits. However, PCL-YV scores were unrelated to participants' official criminal records for total, non-violent, violent, and technical violation convictions. In conclusion, the data partially support the construct validity of psychopathy with adolescent offenders, but some inconsistencies with prior adult and adolescent psychopathy research were evident. These issues are discussed.     

Team learning: collectively connecting the dots

This article tests the degree to which personal and situational variables impact the acquisition of knowledge and skill within interactive project teams. On the basis of the literature regarding attentional capacity, constructive controversy, and truth-supported wins, the authors examined the effects of cognitive ability, workload distribution, Agreeableness, Openness to Experience, and structure on team learning. Results from 109 four-person project teams working on an interdependent command and control simulator indicated that teams learned more when composed of individuals who were high in cognitive ability and when the workload was distributed evenly. Conversely, team learning was negatively affected when teams were composed of individuals who were high in Agreeableness. Finally, teams using a paired structure learned more than teams structured either functionally or divisionally. Theoretical and practical implications are discussed, as well as possible limitations and directions for future research.     

Breaking the waves: age differences in electrical brain activity when reading text with distractors

The authors tested whether older adults have greater difficulty than younger adults in ignoring task-irrelevant information during reading as a result of age-related decline in inhibitory processes. Participants were shown target sentences containing distractor words. They were instructed to read aloud each sentence and ignore distractors. The N400 event-related potential (ERP) was used to measure the extent of semantic processing of target and distracting information. It showed that younger adults semantically processed both target and distracting material, whereas online processing of target sentences in older adults was disrupted by the distractors. In older adults, memory for target information related to their susceptibility to distraction and inhibition efficiency. Implications for age-differences in inhibitory control, working memory, and resource capacity are discussed.     

The interaction of personality and job scope in predicting turnover

The interaction of employee personality characteristics and job scope in the prediction of turnover was studied. One hundred and nine individuals employed as machine operators (low-scope job) and scientific and technical personnel (high-scope job) within a large manufacturing organization were the sample. No direct relationships were found between personality characteristics and turnover for the combined sample of employees on high- and low-scope jobs. When correlational analyses were carried out within job scope samples it was evident that personality and job scope interacted in predicting turnover. For employees on high-scope jobs, turnover was negatively related to the need for achievement and positively related to the need for affiliation. Turnover was negatively related to the need for affiliation among employees on low-scope jobs. The implications of these findings for future research on turnover were discussed.