Microstructural organization of corpus callosum projections to prefrontal cortex predicts bimanual motor learning

The corpus callosum (CC) is the largest white matter tract in the brain. It enables interhemispheric communication, particularly with respect to bimanual coordination. Here, we use diffusion tensor imaging (DTI) in healthy humans to determine the extent to which structural organization of subregions within the CC would predict how well subjects learn a novel bimanual task. A single DTI scan was taken prior to training. Participants then practiced a bimanual visuomotor task over the course of 2 wk, consisting of multiple coordination patterns. Findings revealed that the predictive power of fractional anisotropy (FA) was a function of CC subregion and practice. That is, FA of the anterior CC, which projects to the prefrontal cortex, predicted bimanual learning rather than the middle CC regions, which connect primary motor cortex. This correlation was specific in that FA correlated significantly with performance of the most difficult frequency ratios tested and not the innately preferred, isochronous frequency ratio. Moreover, the effect was only evident after training and not at initiation of practice. This is the first DTI study in healthy adults which demonstrates that white matter organization of the interhemispheric connections between the prefrontal structures is strongly correlated with motor learning capability.     

Effort and Aspirations in Tax Evasion: Experimental Evidence

Is the effort exerted to earn taxable income considered in compliance decisions? And if so, is hard‐earned income or easy money more likely to be concealed from authorities? While economic theory postulates that prior costs should not affect present decisions, psychological research shows that prior investments of money, time, or effort do matter. Findings from previous studies on the impact of effort on abstract decision tasks suggest two contradictory predictions for the context of tax compliance decisions: Either taxable income earned by high effort is subjectively of higher value, and therefore more likely to be evaded, or investments of effort cause a shift of the reference point through the establishment of an aspiration level, resulting in honest declaration of income. Two experiments were conducted to test these predictions. In a business simulation, taxable income was obtained by different levels of effort and consequently had to be reported to authorities. Results show that tax evasion was more pronounced in low‐effort conditions. This suggests that effort changes the reference point rather than the slope, and provides evidence that in tax compliance decisions aspiration levels serve as reference points. Implications for tax audits are discussed. L'effort déployé pour obtenir des revenus imposables est‐il pris en compte dans les décisions qui en découlent? Et si c'est le cas, est‐ce l'argent facile ou les revenus durement gagnés qui présentent une plus forte probabilité d'être soustraits au fisc? Alors que la théorie économique postule que le coût antérieur n'a pas de retombées sur les décisions présentes, les recherches de psychologie montrent que les investissements passés en argent, temps ou effort ont leur importance. Des travaux sur l'impact de l'effort sur des tâches de décision abstraite débouchent sur deux prédictions contradictoires en ce qui concerne les décisions relatives à l'impôt: ou le revenu imposable obtenu à la suite d'un effort substantiel est subjectivement fortement valorisé et a de fortes chances d'être camouflé, ou l'effort investi provoque un changement de référence à travers l'instauration d'un niveau d'aspiration, ce qui a pour conséquence une déclaration honnête des revenus. On a réalisé deux expériences pour mettre à l'épreuve ces prédictions. Dans une simulation commerciale, le revenu imposable a été obtenu suite à différents niveaux d'effort et devait être portéà la connaissance du fisc. Les résultats montrent que l'évasion fiscale était plus accentuée dans les conditions où l'effort était modeste. Il faut en conclure que l'effort entraîne une mutation du système de référence plutôt qu'une simple modification de niveau et que dans les décisions relatives à l'impôt les niveaux d'aspiration servent de point de référence. On réfléchit aux leçons à en tirer pour le contrôle fiscal.     

Test anxiety,working memory,and cognitive performance: Supportive effects of sequential demands

Substantial evidence suggests that test anxiety is associated with poor performance in complex tasks. Based on the differentiation of coordinative and sequential demands on working memory (Mayr & Kliegl, 1993), two studies examined the effects of sequential demands on the relationship between test anxiety and cognitive performance. Both studies found that high sequential demands had beneficial effects on the speed and accuracy of the performance of test-anxious participants. It is suggested that the more frequent memory updates associated with high sequential demands may represent external processing aids that compensate for the restricted memory capacity of individuals with high test anxiety.     

Serial murderers' spatial decisions: factors that influence crime location choice

The outcome of German serial murderer spatial decision making was measured as the straight‐line distance (km) between murderer home locations and each crime location (i.e. body recovery location). Geographic and series development data, as well as information on age, intelligence, motive, marital status, employment status, and mode of transportation of 53 German serial murderers was collected from police and prosecution service files and judicial verdict records. Potential effects of the aforementioned factors on spatial decisions were assessed. Results showed that 63% of the murderers lived within 10 km of their crime locations. Home‐to‐crime distance was negatively correlated with murderer age and positively correlated with murderer IQ score. Results also showed that the mode of transportation used by murderers had an effect on their spatial decisions. Results are discussed in terms of understanding serial murderer spatial decision‐making and implications for police investigations. Copyright © 2005 John Wiley & Sons, Ltd.     

Cognitive Processes Underlying Observational Learning of Motor Skills

There is evidence indicating that an individual can learn a motor skill by observing a model practising it. In the present study we wanted to determine whether observation would permit one to learn the relative timing pattern required to perform a new motor skill. Also, we wanted to determine the joint effects of observation and of physical practice on the learning of that relative timing pattern. Finally, we were interested in finding whether there was an optimal type of model, advanced or beginner, which would lead better to observational learning. Data from two experiments indicated that observation of either a beginner or an advanced model resulted in modest learning of a constrained relative timing pattern. Observation also resulted in significant parameterization learning. However, a combination of observation followed by physical practice resulted in significant learning of the constrained relative timing pattern. These results suggest that observation engages one in cognitive processes similar to those occurring during physical practice.     

Associations between violence,criminality, and cognitive control deficits among young men living in low resource communities in South Africa

Despite empirical support for “Self-control theory” in criminology, there is controversy about how self-control should be operationalized. Working within the framework of “self-control theory,” we investigated if violence and criminal behaviors are associated with nine distinct dimensions of cognitive control in a community sample of young men (n = 654) living in peri-urban townships in South Africa. Cognitive control was assessed using the Behavior Rating Inventory of Executive Function. Multivariate statistical analysis was used, to identify associations between violence and criminality, and deaggregated measures of nine distinct components of cognitive control. Fifteen percent of the sample reported recent violence, 27% had been in physical fights with family/friends in the preceding 6 months, 10% reported being arrested, 4% reported forced sexual contact, and 26% reported intimate partner violence (IPV). Controlling for substance use and sociodemographic variables, contact with the criminal justice system and violence were associated with deficits in all domains of cognitive control. Forced sexual contact was associated with behavioral dysregulation. IPV was associated with behavior dysregulation and executive control dysfunction. Future studies might utilize deaggregated measures of self-control to provide further insight into links between particular components of cognitive control and various forms of offending and violence.     

How Do Job Insecurity and Organizational Justice Relate to Depressive Symptoms and Sleep Difficulties: A Multilevel Study on Immediate and Prolonged Effects in Swedish Workers

Drawing on stress and justice literature, we argue that perceptions of job insecurity induce feelings of low procedural justice, which has immediate and prolonged negative effects on health (depressive symptoms, sleep difficulties). Moreover, we explore whether the strength of the job insecurity–justice relationship differs between individuals as a function of their average level of job insecurity over time. Finally, we explore whether the procedural justice–health relationship differs between individuals as a function of variability in justice perceptions over time. We analyzed Swedish panel data from permanent workers over four consecutive waves (with a two-year time lag between waves) using multilevel analysis, separating within- and between-person variance. Results showed that job insecurity associated negatively with procedural justice at the same time point for all waves. Prolonged effects were less stable. We found immediate (but not prolonged) indirect effects of job insecurity on health outcomes via procedural justice. Average levels in job insecurity over time moderated the within-person job insecurity–justice relationship. However, variability in procedural justice over time did not moderate the within-person justice–health relationship. In conclusion, disentangling within- and between-person variability of job insecurity and justice perceptions contributes to the understanding of health effects.