Experimental study of the differential effects of playing versus watching violent video games on children's aggressive behavior

There is great concern about the effects of playing violent video games on aggressive behavior. The present experimental study was aimed at investigating the differential effects of actively playing vs. passively watching the same violent video game on subsequent aggressive behavior. Fifty-seven children aged 10-13 either played a violent video game (active violent condition), watched the same violent video game (passive violent condition), or played a non-violent video game (active non-violent condition). Aggression was measured through peer nominations of real-life aggressive incidents during a free play session at school. After the active participation of actually playing the violent video game, boys behaved more aggressively than did the boys in the passive game condition. For girls, game condition was not related to aggression. These findings indicate that, specifically for boys, playing a violent video game should lead to more aggression than watching television violence.     

Physical growth delays and stress dysregulation in stunted and non-stunted Ukrainian institution-reared children

To study the effect of institutional rearing on physical growth and stress regulation we examined 16 institution-reared children (3–6 years old) in Ukraine and compared them with 18 native family-reared children pair-matched on age and gender. Physical growth trajectories were examined on the basis of archival medical records and current measurements of height, weight, and head circumference. Stress regulation was studied on the basis of diurnal salivary cortisol sampled six times during 1 day. 31% of institution-reared children were stunted at 48 months whereas none of the family-reared children were. Substantial delays in physical growth were observed in institution-reared children especially during the first year of life. From 24 months onwards a tendency for improvement in physical growth was evident among the temporarily stunted institution-reared children, with complete catch-up in weight and partial catch-up in height by the time of assessment. Chronically stunted institution-reared children demonstrated persistent severe growth delays. Institution-reared and family-reared children showed similar patterns of diurnal cortisol production with decreases over the day. However, temporarily stunted institution-reared children had a significantly higher total daily cortisol production than both chronically stunted institution-reared children and family-reared children. These data confirm previous findings regarding physical growth delays and stress dysregulation associated with institutional care, but also point to differences in cortisol production between stunted and non-stunted institution-reared children.     

Neurophysiology and neuroanatomy of reflexive and voluntary saccades in non-human primates

A multitude of cognitive functions can easily be tested by a number of relatively simple saccadic eye movement tasks. This approach has been employed extensively with patient populations to investigate the functional deficits associated with psychiatric disorders. Neurophysiological studies in non-human primates performing the same tasks have begun to provide us with insights into the neural mechanisms underlying many cognitive functions. Here, we review studies that have investigated single neuron activity in the superior colliculus (see glossary), frontal eye field, supplementary eye field, dorsolateral prefrontal cortex, anterior cingulate (see glossary) cortex and lateral intraparietal area associated with the performance of visually guided saccades, anti-saccades and memory-guided saccades in awake behaving monkeys.     

Motor asymmetry and substantia nigra volume are related to spatial delayed response performance in Parkinson disease

Studies suggest motor deficit asymmetry may help predict the pattern of cognitive impairment in individuals with Parkinson disease (PD). We tested this hypothesis using a highly validated and sensitive spatial memory task, spatial delayed response (SDR), and clinical and neuroimaging measures of PD asymmetry. We predicted SDR performance would be more impaired by PD-related changes in the right side of the brain than in the left. PD (n = 35) and control (n = 28) participants performed the SDR task. PD participants either had worse motor deficits on the right (RPD) or left (LPD) side of the body. Some participants also had magnetic resonance imaging for measurement of their substantia nigra (SN) volumes. The LPD group performed worse on the SDR task than the RPD and control groups. Right SN volume accounted for a unique and significant portion of the variance in SDR error, with smaller volume predicting poorer performance. In conclusion, left motor dysfunction and smaller right SN volume are associated with poorer spatial memory.     

At first glance, transparency enhances assimilation

We investigated the role of transparency, perceptual grouping, and presentation time on perceived lightness. Both transparency and perceptual grouping have been found to result in assimilation effects, but only for ambiguous stimulus displays and with specific attentional instructions. By varying the presentation times of displays with two partly overlapping transparent E-shaped objects, we measured assimilation in unambiguous stimulus displays and without specific attentional instructions. The task was to judge which of two simultaneously presented E-shaped objects was darker. With unrestrained presentation times, if a transparency interpretation was possible, assimilation was not found. Inhibiting a transparency interpretation by occluding the local junctions between the two E-shaped objects, did lead to assimilation. With short presentation times, if a transparency interpretation was possible, assimilation was now also found. Thus, we conclude that, although transparency appears to enhance assimilation, with unambiguous stimulus displays and without specific attentional instructions, perceptual grouping is more important for assimilation to occur.     

Event-related potentials, reaction time, and response selection of skilled and less-skilled cricket batsmen

The differences in P300 latency, P300 amplitude, response selection, and reaction time between skilled and less-skilled cricket batsmen have been investigated. Eight skilled and ten less-skilled right-handed batsmen each viewed 100 in-swing, 100 out-swing, and 40 slower deliveries displayed in random sequence from projected video footage whilst their responses and electroencephalograms were recorded. Logistic regression was used to derive a discriminative function for the P300 data. This was done to determine whether the skilled batsmen differed from the less-skilled batsmen on the basis of pooled P300 amplitude and latency data. All the batsmen were correctly characterised as being skilled or less-skilled. Logistic regression equations with reaction time and correctness of response data indicated that behavioural data do not correctly classify skilled performance. It is suggested that skilled cricket batsmen have a superior perceptual decision-making ability compared with less-skilled cricket batsmen, as measured by P300 latency and amplitude. This appears to be the first study showing a link between skill and cerebral cortical activity during a perceptual cricket batting task and it could pave the way for future studies on mental processing in cricket batsmen.     

The human Müller-Lyer illusion in goalkeeping

We examined whether a goalkeeper can influence a penalty-taker's actions by assuming postures that mimic Müller-Lyer configurations. The results of two studies indicate that (i) goalkeeper posture affects the perception of the goalkeeper's height in a manner consistent with the Müller-Lyer illusion; (ii) this influences penalty-taking accuracy; and (iii) a posture which resembles a wing-out Müller-Lyer configuration results in wider and lower throws.     

The virtues of epistemic conservatism

Although several important methodologies implicitly assume the truth of epistemic conservatism, the view that holding a belief confers some measure of justification on the belief, recent criticisms have led some to conclude that epistemic conservatism is an implausible view. That conclusion is mistaken. In this article, I propose a new formulation of epistemic conservatism that is not susceptible to the criticisms leveled at earlier formulations of epistemic conservatism. In addition to withstanding these criticisms, this formulation of epistemic conservatism has several benefits. First, this formulation has the benefits of earlier formulations of epistemic conservatism, that is to say it makes sense of our intuitions about justification in regard to both memory beliefs and beliefs for which we have forgotten our evidence. Second, it provides a good way of responding to the skeptic’s challenge concerning the possibility of possessing knowledge of the external world posed by the Alternative Hypotheses argument. Third, it provides responses to both forms of a new skeptical problem plaguing basic knowledge structure theories, the Problem of Easy Knowledge formulated by Stewart Cohen. I argue that given the many benefits of this formulation of epistemic conservatism and the fact that it is not vulnerable to the criticisms that undermine earlier formulations of epistemic conservatism, this formulation of epistemic conservatism is a plausible view to maintain.     

The many faces of interpolation

We present a number of, somewhat unusual, ways of describing what Craig’s interpolation theorem achieves, and use them to identify some open problems and further directions.     

Executive Functions in Preschool Children with Aggressive Behavior: Impairments in Inhibitory Control

The question whether executive function (EF) deficits in children are associated with conduct problems remains controversial. Although the origins of aggressive behavior are to be found in early childhood, findings from EF studies in preschool children with aggressive behavior are inconsistent. The current study aimed to investigate whether preschool children with aggressive behavior show impairments in EF. From a population-based sample, 82 preschool children who were showing aggressive behavior as indicated by scores at or above the 93rd percentile on the Aggressive Behavior Scale of the CBCL 1 1/2-5 were selected. These children with aggressive behavior were matched on IQ to a group of typically developing control children (N = 99). Six neuropsychological tasks were administered to assess set shifting, inhibition, working memory and verbal fluency. A factor analysis was conducted which yielded one clear factor: inhibition. Aggressive preschool children showed poorer performance on this inhibition factor than control children and boys performed worse on this factor than girls. This association between aggressive behavior and inhibition deficits was maintained after controlling for attention problems. In addition, gender differences in all EFs measured were found with boys exhibiting more impairment in EF than girls. These findings demonstrate that preschool children with aggressive behavior show impairments in inhibition, irrespective of attention problems.