Prevalence of alcohol use in a rural South African community

Among a community sample of 801 rural South Africans, 22.2% of men and 5.0% of women were classified as high-risk drinkers and 3.3% as with probable alcohol dependence.     

Anticipatory postural adjustments for altering direction during walking

The authors examined how individuals adapt their gait and regulate their body configuration before altering direction during walking. Eight young adults were asked to change direction during walking with different turning angles (0 degree, 45 degree, 90 degree), pivot foot (left, right), and walking speeds (normal and fast). The authors used video and force platform systems to determine participants' whole-body center of mass and the center of pressure during the step before they changed direction. The results showed that anticipatory postural adjustments occurred during the prior step and occurred earlier for the fast walking speed. Anticipatory postural adjustments were affected by all 3 variables (turn angle, pivot foot, and speed). Participants leaned backward and sideward on the prior step in anticipation of the turn. Those findings indicate that the motor system uses central control mechanisms to predict the required anticipatory adjustments and organizes the body configuration on the basis of the movement goal.     

Perception of biological motion: A stimulus set of human point-light actions

We present a set of stimuli representing human actions under point-light conditions, as seen from different viewpoints. The set contains 22 fairly short, well-delineated, and visually “loopable” actions. For each action, we provide movie files from five different viewpoints as well as a text file with the three spatial coordinates of the point lights, allowing researchers to construct customized versions. The full set of stimuli may be downloaded fromwww.psychonomic.org/archive/.     

Support vector machines categorize the scaling of human grip configurations

In previous work (Cesari & Newell, 2002), we used a graphical dimensional analysis to show that grip transitions obey the body-scaled relation K = lnL(o) + InM(o)h/(a + bM(h) + cL(h)), where L. and Mo are the object's length and mass, and Lh and Mh the length and mass of the grasper's hand. However, the generality of the equation was limited by the ad hoc graphical method that defined the lines for grip separation and by the assumption that these lines be negatively sloped and parallel to one another. This article reports an independent test of this relation by the geometrical and statistical categorization of body-scaled invariants for the transition of human grip configurations through support vector machines (SVMs). The SVM analysis confirmed the fit of linear, negatively sloped, and approximately parallel transition boundaries in the scaling of human grip configuration within a single hand. The SVM analysis has provided a theoretical refinement to the scaling model of human grip configurations.     

Stress-response-dampening effects of alcohol: attention as a mediator and moderator

The present study sought to characterize alcohol's stress-response-dampening (SRD) effects on multiple measures of stress and whether these effects are mediated by reductions in sustained attention and, further, whether baseline levels of sustained attention moderate SRD. One hundred six men consumed either an alcohol (0.70 g/kg) or a placebo beverage prior to learning that they would deliver a self-disclosing speech. Structural equation models controlling for multiple baseline periods indicated that alcohol directly reduced self-reported anxiety and skin conductance levels in response to the stressor. Alcohol's effect on reducing heart rate response, in contrast, was indirect and mediated by effects on prestress baseline. As hypothesized, differences in sustained attention partially mediated the effects of alcohol on skin conductance (but not heart rate or self-reported anxiety) and served as a moderator of alcohol's effects on skin conductance response. Findings are discussed in terms of theoretical links among alcohol consumption, specific cognitive abilities, and stress reactivity.