Neuromotor profiles: what are they and what can we learn from them?

Eye movements, alternating movements, rapid pointing movements, and various tremors were measured on patients with Parkinson's disease (n = 21), on Cree subjects exposed to methylmercury (n = 36), and on healthy control subjects (n = 30). Neuromotor profiles were created according to thirty characteristics extracted from test results of four subgroups matched for age and composed of six subjects each. Z scores were calculated with respect to the mean and standard deviation of the control group for each of the 30 characteristics. The subgroup with the lower methylmercury blood level had larger z scores than the control subgroup and with a few positive values above one standard deviation. The subgroup with the higher methylmercury blood level had several z scores above two standard deviations. Interestingly, the abnormal values for the subgroup with Parkinson's disease were mostly limited to static tremor recorded with no visual feedback and reached up to 5 standard deviations. These results indicate that neuromotor profiles can be used to summarize information extracted from different neuromotor tests and to differentiate neurological conditions.     

Reliability and validity of a self-efficacy instrument specific to sickle cell disease

The psychometric properties of a new, 9-item scale measuring disease-specific perceptions of self-efficacy were investigated in a community-based sample of adults (N = 83) with sickle cell disease (SCD). The Sickle Cell Self-Efficacy Scale (SCSES) was comprised of nine questions relating to participants' perceptions of their ability to function on a day-to-day basis and to manage SCD symptomatology (e.g. episodes of pain). The SCSES demonstrated good internal consistency, discriminant validity, and convergent and predictive validity, both with previously validated measures of related constructs as well as with reported SCD symptomatology. Overall, the instrument appears to be reliable and valid for assessing clients' self-efficacy for engaging successfully in day-to-day activities despite having SCD. Future investigators may wish to examine temporal and causal links between alterations in self-efficacy and changes in adjustment to sickle cell disease; the SCSES provides a psychometrically sound tool with which to investigate these phenomena.     

Infants' formation and use of categories to segregate objects

Four- and-a-half-month-old infants' (N = 100) category formation and use was studied in a series of five experiments. For each experiment, the test events featured a display composed of a cylinder and a box. Previous research showed that this display is not clearly parsed as a single unit or as two separate units by infants of this age. Immediately prior to testing, infants were shown a set of category exemplars. Knowledge about this category could help infants disambiguate the test display, which contained a novel exemplar of this category. Clear interpretation of the test display as composed of two separate units (as indicated by infants' longer looking at the move-together than at the move-apart test event) was taken as evidence of category formation and use. In Experiments 1 and 5, infants' prior experience with a set of three different boxes that were similar to the test box facilitated their segregation of the test display. Experiment 2 showed that three different exemplars are necessary: prior experience with any two of the three boxes used in Experiment 1 did not facilitate infants' segregation of the test display. Experiment 3 showed that variability in the exemplar set is necessary: prior experience with three identical boxes did not facilitate infants' segregation of the test display. Experiment 4 showed that under these conditions of very brief prior exposure, similarity between the exemplar set and test box is necessary: prior experience with three different boxes that were not very similar to the test box did not facilitate infants' segregation of the test display. Together, these findings suggest that: (a) number of exemplars, variability, and similarity in the exemplar set are important for infants' category formation, and (b) infants use their category knowledge to determine the boundaries of the objects in a display.     

The effect of school-based kindergarten transition policies and practices on child academic outcomes

This study examined the effect of school-based kindergarten transition policies and practices on child outcomes. The authors followed 17,212 children from 992 schools in the Early Childhood Longitudinal Study-Kindergarten sample (ECLS-K) across the kindergarten school year. Hierarchical linear modeling revealed that the number of school-based transition practices in the fall of kindergarten was associated with more positive academic achievement scores at the end of kindergarten, even controlling for family socioeconomic status (SES) and other demographic factors. This effect was stronger for low- and middle-SES children than high-SES children. For low-SES children, 7 transition practices were associated with a .21 standard deviation increase in predicted achievement scores beyond 0 practices. The effect of transition practices was partially mediated by an intervening effect on parent-initiated involvement in school during the kindergarten year. The findings support education policies to target kindergarten transition efforts to increase parent involvement in low-SES families.     

The social context of imitation in infancy

Infants increasingly generalize deferred imitation across environmental contexts between 6 and 18 months of age. In three experiments with 126 6-, 9-, 12-, 15-, and 18-month-olds, we examined the role of the social context in deferred imitation. One experimenter demonstrated target actions on a hand puppet, and a second experimenter tested imitation 24h later. When the second experimenter was novel, infants did not exhibit deferred imitation at any age; when infants were preexposed to the second experimenter, all of them did. Imitating immediately after the demonstration also facilitated deferred imitation in a novel social context at all ages but 6 months. Infants' pervasive failure to exhibit deferred imitation in a novel social context may reflect evolutionary selection pressures that favored conservative behavior in social animals.     

The construct of work commitment: testing an integrative framework

This study meta-analytically examined extensive literature associated with work commitment. The primary purposes were to (a) cumulate correlations among dimensions of work commitment to see which were intercorrelated and (b) determine impact of work commitment dimensions and subdimensions on specific outcome variables (job satisfaction, job performance, turnover intentions, and turnover). Results were cumulated across 997 articles. The positive manifold of correlations suggests the presence of a common psychological construct underlying different commitment forms, with the exception of calculative, continuance, and union commitment. Most of the 94 meta-analyzed correlations were small, suggesting that concept redundancy is not a major concern. Meta-analyses of the correlations of 24 commitment constructs with 4 outcome variables suggest that different commitment forms have similar patterns of correlations with outcome variables.     

The influence of restricted viewing conditions on egocentric distance perception: implications for real and virtual indoor environments

We carried out three experiments to examine the influence of field of view and binocular viewing restrictions on absolute distance perception in real-world indoor environments. Few of the classical visual cues provide direct information for accurate absolute distance judgments to points in the environment beyond about 2 m from the viewer. Nevertheless, in previous work it has been found that visually directed walking tasks reveal accurate distance estimations in full-cue real-world environments to distances up to 20 m. In contrast, the same tasks in virtual environments produced with head-mounted displays (HMDs) show large compression of distance. Field of view and binocular viewing are common limitations in research with HMDs, and have been rarely studied under full pictorial-cue conditions in the context of distance perception in the real-world. Experiment 1 showed that the view of one's body and feet on the floor was not necessary for accurate distance perception. In experiment 2 we manipulated the horizontal and the vertical field of view along with head rotation and found that a restricted field of view did not affect the accuracy of distance estimations when head movement was allowed. Experiment 3 showed that performance with monocular viewing was equal to that with binocular viewing. These results have implications for the information needed to scale egocentric distance in the real-world and reduce the support for the hypothesis that a limited field of view or imperfections in binocular image presentation are the cause of the underestimation seen with HMDs.