A meta-analytic review of stopping performance in attention-deficit/hyperactivity disorder: deficient inhibitory motor control?

This review discusses whether deficient inhibitory motor control is the core deficit of attention-deficit/hyperactivity disorder (ADHD). Inhibitory motor control is commonly assessed using the stop-signal paradigm. Since the last meta-analysis that was performed, 33 new studies have appeared. The current meta-analysis revealed a significant difference between ADHD patients and matched controls in stop latency (stop-signal reaction time) in both children and adults. Basic reaction time was significantly longer in children with ADHD, but not in adults, and there was a significant interaction between the elongation of the latency to stop and to respond in adults, but not in children. Deficient inhibitory motor control may be less crucial in children than in adults with ADHD.     

Leader self-sacrifice and leadership effectiveness: the moderating role of leader prototypicality

Self-sacrificing behavior of the leader and the extent to which the leader is representative of the group (i.e., group prototypical) are proposed to interact to influence leadership effectiveness. The authors expected self-sacrificing leaders to be considered more effective and to be able to push subordinates to a higher performance level than non-self-sacrificing leaders, and these effects were expected to be more pronounced for less prototypical leaders than for more prototypical leaders. The results of a laboratory experiment showed that, as expected, productivity levels, effectiveness ratings, and perceived leader group-orientedness and charisma were positively affected by leader self-sacrifice, especially when leader prototypicality was low. The main results were replicated in a scenario experiment and 2 surveys.     

The evolution of domain-general mechanisms in intelligence and learning

For both humans and animals, domain-general mechanisms are fallible but powerful tools for attaining evolutionary goals (e.g., resources) in uncertain, novel environments that were not recurrent features of the environment of evolutionary adaptedness. Domain-general mechanisms interact in complex ways with domain-specific, information-encapsulated modules, most importantly by manipulating information obtained from various modules in attempting to solve novel problems. Mechanisms of general intelligence, particularly the executive functions of working memory, underlie analogical reasoning as well as the decontextualization processes that are central to human thought. Although there is a variety of evolved, special purpose learning devices, learning is also characterized by domain-general mechanisms that are able to achieve evolutionary goals by making novel and serendipitous associations with environmental cues.     

Gender differences in leg stiffness and stiffness recruitment strategy during two-legged hopping

The authors compared leg stiffness (K(VERT)), muscle activation, and joint movement patterns between 11 men and 10 women during hopping. Physically active and healthy men and women performed continuous 2-legged hopping at their preferred rate and at 3.0 Hz. Compared with men, women demonstrated decreased K(VERT); however, after the authors normalized for body mass, gender differences in K(VERT) were eliminated. In comparison with men, women also demonstrated increased quadriceps and soleus activity, as well as greater quadriceps-to-hamstrings coactivation ratios. There were no significant gender differences for joint movement patterns (p>.05). The relationship between the observed gender differences in muscle recruitment and the increased risk of anterior cruciate ligament injury in women requires further study.     

An illustration of multilevel factor analysis

The factor analysis of repeated measures psychiatric data presents interesting challenges for researchers in terms of identifying the latent structure of an assessment instrument. Specifically, repeated measures contain both within and between individual sources of variance. Although a number of techniques exist for separating out these 2 sources of variance, all are problematic. Recently, researchers have proposed that exploratory multilevel factor analysis (MFA) be used to appropriately analyze the latent structure of repeated measures data. The chief objective of this report is to provide a didactic step-by-step guide on how MFA may be applied to psychiatric data. In the discussion, we describe difficulties associated with MFA and consider challenges in factor analyzing life event appraisals in psychiatric samples.     

Luminance edges are not necessary for visual completion

Luminance edges seem to have an important role in visual feature binding and, more specifically, in visual completion because luminance differences are important for the perception of depth. We investigated this claim in two experiments in which the primed-matching paradigm was used. In Experiment 1, we investigated conditions under which either a partly occluded shape or an occluder was isoluminant with respect to the background. In Experiment 2, the partly occluded shape and the occluder were isoluminant with respect to each other. Evidence was found for visual completion in all cases, and we therefore conclude that luminance edges are not essential for visual completion.     

An examination of Euro-American and African-American differences in social physique anxiety among college women

Many studies have examined sex differences in social physique anxiety; however, few researchers have examined possible perceptual differences in such anxiety based on ethnicity. The present purpose was to examine social physique anxiety among college-age women of Euro-American and African-American descent. Participants (N = 91) from physical activity classes at a university located in the southeastern United States completed the Social Physique Anxiety Scale. The participants were 67 Euro-Americans and 24 African Americans. An independent t test yielded a significant difference (p =.01) between groups on Eklund's scale, which supports the hypothesis.     

Correlations among family environment, academic achievement, and academic attainment in a large sample of young Australian adults

In a set of interrelated Australian and Spanish investigations in 2001-2004, relationships were examined among intellectual ability, family environment, and academic achievement. This follow-up study used longitudinal data from young Australian adults (4,397 men, 4,703 women; M age = 20.2 yr., SD = 0.4), to investigate relationships among earlier academic achievement, family influences, and academic attainment. From multiple regression and commonality analyses the findings indicated that earlier achievement and family influences were important as separate variables in explaining differences in later academic attainment (18.6% and 14.8%, respectively, for men; 14.5% and 11.5%, respectively, for women). In addition, earlier achievement and family influences reinforced each other to account for additional shared variance (9.1% for men, 6.3% for women) in young Australian adults' academic attainment.     

Characteristics of true versus false allegations of sexual offences

The goal of the study was to establish whether false allegations of sexual offences with an unknown perpetrator can be distinguished from accurate allegations. Case files of 27 true allegations of sexual offences with an unknown perpetrator were compared to those of 14 false allegations. The comparison was guided by a list of 43 criteria that are hypothesized to differentiate between true and false allegations of sexual assault. Analyses indicated the employed criteria differentiated true from false allegations to a certain extent. However, the discriminative strength of some criteria appeared to be stronger than that of others. Research is required to assess further the discriminative power of these criteria.     

Effects of stop signal modality, stop signal intensity and tracking method on inhibitory performance as determined by use of the stop signal paradigm

In Experiment 1, the effects of stop signal modality on the speed and efficiency of the inhibition process were examined. Stop signal reaction time (SSRT) and inhibition function slope in an auditory stop signal condition were compared to SSRT and inhibition function slope in a visual stop signal condition. It was found that auditory stop signals compared to visual stop signals enhanced both the speed and efficiency of stopping. The modality effects were attributed to differences in the neurophysiological processes underlying perception. However, Experiment 2 demonstrated that the modality difference was larger for 80 dB(A) auditory stop signals than 60 dB(A) auditory stop signals. This effect was reconciled with the suggestion that loud tones are more capable of eliciting immediate arousing effects on motor processes than weak tones and visual stimuli. The second purpose of the present investigation was to explore the utility (and potential advantages) of an alternative way of setting stop signal delay relative to mean reaction time (MRT). The method that was suggested compensates for inter-individual differences in primary task reaction speed by setting stop signal delays as proportions of the subjects' MRT.