Changes in the structure of children's isometric force variability with practice

This study examined the effect of age and practice on the structure of children's force variability to test the information processing hypothesis that a reduction of sensorimotor system noise accounts in large part for age-related reductions in perceptual-motor performance variability. In the study, 6-year-olds, 10-year-olds, and young adults practiced on 5 consecutive days (15 trials/day), maintaining for 15-s trials a constant level of force (5 or 25% of maximum voluntary contraction) against an object using a pinch grip (thumb and index finger). With increasing age, the amount of force error and variability decreased, but the sequential structure of variability increased in irregularity. With practice, children reduced the amount of variability by changing the structure of the force output so as to be more similar to that of their older counterparts. The findings provide further evidence that practice-driven changes in the structure of force output, rather than a decline in the amount of white noise, largely account for age-related reductions in the amount of force variability.     

The force of symmetry revisited: symmetry-to-noise ratios regulate (a)symmetry effects

Freyd and Tversky's [Am. J. Psychol. 97 (1984) 109] data suggested that human observers tend to overestimate relatively high levels of symmetry (symmetry effect), and tend to underestimate relatively low levels of symmetry (asymmetry effect). However, on the basis of their holographic approach to visual regularity, van der Helm and Leeuwenberg [Psychol. Rev. 103(3) (1996) 429] predicted that, at any level of symmetry, both symmetry and asymmetry effects may occur as a consequence of correct estimates of symmetry-to-noise ratios. This prediction was tested in two experiments, with tasks and stimuli similar to those in Freyd and Tversky's study. First, subjects had to judge whether a noisy symmetry is more similar to a slightly more symmetrical variant or to a slightly less symmetrical variant. Second, for every pair of stimuli in such a triadic comparison, subjects had to judge which stimulus is the more symmetrical one. The results from both experiments show that the occurrence of (a)symmetry effects indeed depends on symmetry-to-noise ratios.     

Phonologically mediated priming of preexisting and new associations in young and older adults

In 2 experiments, the authors investigated phonologically mediated priming of preexisting and new associations in word retrieval. Young and older adults completed paired word stems with the first word that came to mind. Priming of preexisting associations occurred when word-stem pairs containing homophones (e.g., beech-s____) showed more completions with the target (e.g., sand) relative to unrelated pairs (e.g., batch-s____), with more priming for subordinate than for dominant homophones. Priming occurred for new associations independent of dominance such that word-stem pairs containing homophones (e.g., beech-l____ and beach-l____) were completed with the same word (e.g., laugh) more often than unrelated pairs (e.g., beech-l____ and batch-l____). No age differences in phonologically mediated priming were found for either type of association, suggesting age equivalence in the use of bottom-up phonological connections.     

An experimental test of the effect of weight-loss dieting on bulimic pathology: tipping the scales in a different direction

Although it is widely accepted that dieting increases the risk for bulimic pathology, this hypothesis has not been tested in a randomized experiment. Accordingly, the authors conducted an experimental test of the dietary restraint model by randomly assigning nonobese women (N = 82) to either a 6-week, low-calorie diet or a waitlist control condition. The diet intervention resulted in significant weight loss, confirming that dieting was successfully manipulated. Contrary to the restraint model, dieting resulted in significant decreases in bulimic symptoms relative to the control condition. Results converge with past findings from randomized obesity prevention and treatment trials and provide evidence that dieting does not promote bulimic pathology; rather, effective decreases in caloric intake appear to reduce bulimic symptoms.     

Limits of the retrieval-inhibition construct: list segregation in directed forgetting

The authors hypothesized that retrieval inhibition in list method directed forgetting could be improved by presenting a task that maximized the segregation step of the retrieval-inhibition process. In Experiment 1, they presented lists of semantically related words in a list method directed-forgetting task to maximize retrieval inhibition. Contrary to predictions, this manipulation eliminated the directed-forgetting effect. The authors further investigated the results of Experiment 1 in Experiments 2 and 3 by manipulating recall instructions and by presenting lists that contained both a categorized and an unrelated list-half. They found directed-forgetting effects for semantically related word lists when participants were asked to recall only the TBR (to-be-remembered) items but not when participants were asked to recall both the TBF (to-be-forgotten) and TBR items. They also found that directed-forgetting effects were not produced when categorized items were presented in the 1st list.     

Factor structure of the Beck Depression Inventory in a university sample

Factor analysis was performed on the Beck Depression Inventory with a university sample to examine its potential multidimensionality. A principal components analysis with an oblimin and varimax rotation produced a two-factor solution. These factors were labeled Cognitive-Affective and Physiological and accounted for approximately 39% of the common variance. This finding is consistent with multidimensionality of the inventory and with a similar study of college students. The commonalities of the two studies suggest the reliability (internal consistency) of the Cognitive-Affective and Physiological constructs among "minimally" depressed university samples.     

Knowing in advance: the impact of prior event information on memory and event knowledge

We examined the influence of newly acquired information on children's memory and general representation of a personally experienced event. Thirty-five children between the ages of 5 and 7 years participated in the novel event (Visiting the Pirate). The day before participating, children were: (1) provided with new information specific to the up-coming event; (2) engaged in a discussion generally related to the event topic based on existing knowledge; or (3) discussed an unrelated topic. Advance information specific to the event led to better recall and, in particular, to better integration of the experience into a general event representation both soon after the event and at a follow-up interview 4 months later, whereas general discussion of the topic without the event specific information neither enhanced memory reports nor facilitated the integration of event information. Providing information in advance can have significant effects on memory and knowledge acquisition although many variables, including those relating to the specific content of the information, will affect this relation.     

Prevalence of Child and Adolescent Exposure to Community Violence

Emerging as one of the most significant health issues facing American youth today, child and adolescent exposure to community violence has generated much interest across multiple disciplines. Most research to date has focused on documenting the prevalence of community violence and the emotional and behavioral ramifications. This paper provides an overview of the current literature regarding prevalence of youth exposure to community violence, and identifies those areas where further research is warranted. In addition to examining overall rates of community violence exposure, this paper reviews the prevalence of different types of community violence, such as weapon use, physical aggression, and crime-related events. Predictors of community violence exposure, including gender, age, race, socioeconomic status, behavior patterns, and geography, are discussed.