Perceiving depth in point-light actions

The present study investigates how observers assign depth in point-light figures, by manipulating spatiotemporal characteristics of the stimuli. Previous research on the perception of point-light walkers revealed bistability (i.e., that a point-light walker is perceived as either facing the viewer or facing away from the viewer) and the presence of a perceptual bias (i.e., a tendency to perceive the figure as facing the viewer). Here, we study the generality of these phenomena by having observers indicate the global depth orientation of different ambiguous point-light actions. Results demonstrate bistability for all actions, but the presence of a preferred interpretation depends strongly on the performed action, showing that the process of depth assignment takes into account the movements the point-light figure performs. Two additional experiments, using unfamiliar movement patterns without strong semantic correlates, show that purely kinematic aspects of a naction also strongly affect d epth assignment. Together, the results reveal the perception of depth in point-light figures to be a flexible processinvolving both bottom-up and top-down components.     

A Swedish non-word repetition test for preschool children

A Swedish non-word repetition test for preschool children was constructed with the aim of measuring short-term phonological memory, which has been shown to correlate with language development and language proficiency. Normative data based on results for 200 children four to six years of age are presented. An item analysis of the original 30-item test resulted in a shortened 24 non-word version found suitable for four- to six-year old children. Results for this shortened version, which had a Cronbach's alpha of 0.73, showed longer non-words to be more difficult to repeat than shorter ones, and significant effects of age and compatibility of the tester's and the child's accent, but not of gender. The results are discussed within the framework of Baddeley's working memory model.     

The positivity proportion effect: A list context effect in masked affective priming

In the evaluative decision task, participants decide whether target words denote something positive or negative. Positive and negative prime words are known to engender so-called affective priming effects in this task. Primes were sandwich masked, and the proportion of positive to negative target words was manipulated. In Experiment 1, prime valence and positivity proportion interacted, so that primes of the less frequently presented target valence caused larger priming effects. Experiment 2 rendered an explanation of this interaction in terms of response bias unlikely, Experiment 3 ruled out a peripheral locus of the effect, and Experiment 4 ruled out an account in terms of stimulus repetition. The effect is explained by means of an attentional bias favoring the rare kind of valence.     

Learning to coordinate redundant degrees of freedom in a dynamic balance task

The present study investigated Bernstein's [The co-ordination and regulation of movements, 1967] proposal regarding the three stages of learning in the changing coordination and control of redundant joint-space degrees of freedom. Six participants practiced maintaining balance on a moving platform that was sinusoidally translated in the anterior-posterior direction for 30 trials on day 1 and 10 trials on day 2. At the beginning of practice, the motion of the torso and limb segments was less coherent in the attempt to compensate for the movement of the support surface in retaining a balanced posture. However, with practice, the organization of a compensatory postural coordination mode became highly coherent and also progressively utilized the passive, inertial forces generated by the movement of the support surface. The findings support the propositions that: (a) the pathway of change over time in the coordination pattern of the torso and joint motions depends on the task goal and constraints to action and (b) the changes in limb and torso motion are in support of the learning of a global body center of mass/platform dynamic.     

The current status of EHDI programs in the United States

The importance of identifying congenital hearing loss during the first few months of life has been recognized for almost 60 years. Unfortunately, until more effective newborn hearing screening equipment and procedures were developed in the late 1980s, it was not practical to implement programs for identifying hearing loss during the first few months of life. This paper reviews the activities implemented by the federal government in the last 15 years to promote more effective Early Hearing Detection and Intervention (EHDI) programs, and summarizes legislation passed by states related to universal newborn hearing screening. In surveys conducted in 1998 and 2001, State EHDI Coordinators were asked to rate the degree to which various issues were obstacles to implementing effective EHDI programs. The most serious obstacles are the shortage of qualified pediatric audiologists, inadequate reimbursement for screening and diagnosis, and lack of knowledge among primary health care providers about EHDI issues. Opposition to EHDI programs by hospital administrators was rated substantially lower in 2001 than in 1998. State EHDI Coordinators were also surveyed about how well their EHDI program is addressing issues related to screening, diagnosis, early intervention, linkages to medical home providers, tracking and data management, and family support programs. Although substantial progress has been made, many gaps remain with current EHDI programs.     

Animated diagrams in teaching statistics

In this study, we investigated whether computer-animated graphics are more effective than static graphics in teaching statistics. Four statistical concepts were presented and explained to students in class. The presentations included graphics either in static or in animated form. The concepts explained were the multiplication of two matrices, the covariance of two random variables, the method of least squares in linear regression, α error, β error, and strength of effect. A comprehension test was immediately administered following the presentation. Test results showed a significant advantage for the animated graphics on retention and understanding of the concepts presented.     

Transposition asymmetry in immediate serial recall

When participants confuse the position of items in immediate serial recall, they tend to recall transposed items too early rather than too late. This asymmetry of transposition errors was observed in four experiments. It increased as a function of list length, but was independent of report order, output position, cueing condition, and recall mode. The transposition asymmetry is consistent with error patterns in free recall and in regular speech production where transpositions are usually forward-looking. The asymmetry of transposition errors is discussed in terms of models of serial memory.     

Information entropy analysis of discrete aiming movements

Information entropy and mutual information were investigated in discrete movement aiming tasks over a wide range of spatial (20-160 mm) and temporal (250-1250 ms) constraints. Information entropy was calculated using two distinct analyses: (1) with no assumption on the nature of the data distribution; and (2) assuming the data have a normal distribution. The two analyses showed different results in the estimate of entropy that also changed as a function of task goals, indicating that the movement trajectory data were not from a normal distribution. It was also found that the information entropy of the discrete aiming movements was lower than the task defined indices of difficulty (ID) that were selected for the congruence with Fitts' law. Mutual information between time points of the trajectory was strongly influenced by the average movement velocity and the acceleration/deceleration segments of the movement. The entropy analysis revealed structure to the variability of the movement trajectory and outcome that has been masked by the traditional distributional analyses of discrete aiming movements.     

Sociodemographic factors,religiosity, academic performance,and substance use among first-year university students in South Africa

The purpose of this study was to identify the relationships among sociodemographic variables, family background, religiosity, course of study, academic performance, and substance use. The sample included 799 first-year students in the age range of 16 to 49 years (M age 20.1 yr., SD = 3.2) chosen at random from the University of the North in South Africa. A Model Core Questionnaire from the WHO on Substance use was administered. Analysis indicated that women smoked tobacco or cannabis and drank less than men, while women took more stimulants and other opiate type drugs than men. Low scores on religiosity was a predictor for past-month tobacco use alcohol use, binge drinking, cannabis use, and having a drinking or drug problem now. Being a member of a Protestant denominational church or a Roman Catholic was a predictor for past-month tobacco and alcohol use. A family history of drinking or drug problems and being a social science or humanities student were predictive for a current alcohol or drug problem. Economic status, education of parents. living arrangement. and rural-urban differences were not associated with substance use. Findings have implications for prevention programmes.