School barricaded captive-taking: A literature review and critique

Although schools are among the safest places for children and youth, they are the occasional site of violent behavior. One form of violence is the barricaded-hostage event. In this article, the authors review the research literature pertaining to these events. Specifically, studies examining the impact on direct and indirect victims, and responders to these events, are presented and critiqued. Recommendations for future research are also made, followed by a summary and conclusions.     

An explanation of the indentation size effect in ceramics

Abstract

A quantitative model is proposed to explain the indentation size effect (ISE) often observed in the hardness response of hard brittle materials, namely that hardness is observed to increase with decreasing indentation size. The model is based on a mixed elastic/plastic materials deformation response whereby plastic deformation occurs in a discrete manner progressively to relieve stresses created by elastic flexure of the surface at the edges of the indentation. During unloading of the indenter, recovery of the elastic increment of deformation, which precedes each new band of plastic deformation, results in the indentation appearing smaller than expected, particularly as the indentation sizes decrease to approach the scale of the plastic deformation band spacing. The model fits observed experimental data well and analysis of hardness/size data in this way is shown to allow both a bulk hardness value and a characteristic deformation band scale to be calculated for a given sample.     

Increased susceptibility to proactive interference in adults with dyslexia?

Recent findings show that people with dyslexia have an impairment in serial-order memory. Based on these findings, the present study aimed to test the hypothesis that people with dyslexia have difficulties dealing with proactive interference (PI) in recognition memory. A group of 25 adults with dyslexia and a group of matched controls were subjected to a 2-back recognition task, which required participants to indicate whether an item (mis)matched the item that had been presented 2 trials before. PI was elicited using lure trials in which the item matched the item in the 3-back position instead of the targeted 2-back position. Our results demonstrate that the introduction of lure trials affected 2-back recognition performance more severely in the dyslexic group than in the control group, suggesting greater difficulty in resisting PI in dyslexia.     

Relational Security Moderates the Effect of Serotonin Transporter Gene Polymorphism (5-HTTLPR) on Stress Generation and Depression among Adolescents

Previous research demonstrates that carriers of the short allele of the serotonin transporter gene (5-HTTLPR) show both greater susceptibility to depression in response to stressful life events and higher rates of generation of stressful events in response to depression. The current study examines relational security (i.e., self-reported beliefs about attachment security) as a moderator of these effects, building on emerging research suggesting that the short allele acts as a marker of sensitivity to the social environment. Participants were 354 Caucasian adolescents oversampled for maternal depression (137 male, 217 female), assessed at ages 15 and 20. Results indicated that the short allele predicted increased stress generation at age 20 among those with low age 15 security but decreased stress generation among those with high security, and revealed a three-way interaction between age 15 depression, age 15 security, and genotype, where depression predicted stress generation only among short allele carriers with low security. Further, among boys only, security interacted with genotype to predict longitudinal changes in depression diagnosis, with the s-allele predicting relative increases in probability of depression among boys with low security but decreases among boys with high security. Results support the notion of the short allele as a marker of social reactivity, and suggest that attachment security may buffer against the genetic vulnerability introduced by the short allele, in line with predictions of the differential susceptibility theory.     

Early Developmental Trajectories Toward Concepts of Rational Numbers

Difficulties with rational numbers have been explained by a natural number bias, where concepts of natural numbers are inappropriately applied to rational numbers. Overcoming this difficulty may require a radical restructuring of previous knowledge. In order to capture this development, we examined third- to fifth-grade students' understanding of the size of rational numbers across a 1-year period. On three occasions, students answered a test about the size of decimals and fractions. Latent transition analysis allowed profiling five different rational number size concepts and mapping students' developmental trajectories during the early learning of this topic. Development from natural number-based reasoning to mathematically correct understanding was almost nonexistent during this time period. Instead, students appear to move through intermediary concepts. Locating these temporary and mediating number concepts supports the idea of a slow and gradually developing conceptual change in rational numbers.     

The impact of cognitive behavioral therapy on post event processing among those with social anxiety disorder

Individuals with social anxiety are prone to engage in post event processing (PEP), a post mortem review of a social interaction that focuses on negative elements. The extent that PEP is impacted by cognitive behavioral therapy (CBT) and the relation between PEP and change during treatment has yet to be evaluated in a controlled study. The current study used multilevel modeling to determine if PEP decreased as a result of treatment and if PEP limits treatment response for two types of cognitive behavioral treatments, a group-based cognitive behavioral intervention and individually based virtual reality exposure. These hypotheses were evaluated using 91 participants diagnosed with social anxiety disorder. The findings suggested that PEP decreased as a result of treatment, and that social anxiety symptoms for individuals reporting greater levels of PEP improved at a slower rate than those with lower levels of PEP. Further research is needed to understand why PEP attenuates response to treatment.     

Executive turnover: the influence of dispersion and other pay system characteristics

Using tournament theory as a guiding theoretical framework, in this study, we assess the organizational implications of pay dispersion and other pay system characteristics on the likelihood of turnover among individual executives in organizational teams. Specifically, we estimate the effect of these pay system characteristics on executive turnover decisions. We use a multi-industry, multilevel data set composed of executives in publicly held firms to assess the effects of pay dispersion at the individual level. Consistent with previous findings, we find that pay dispersion is associated with an increased likelihood of executive turnover. In addition, we find that other pay characteristics also affect turnover, both directly and through a moderating effect on pay dispersion. Turnover is more likely when executives receive lower portions of overall top management team compensation and when they have more pay at risk. These conditions also moderate the relationship between pay dispersion and individual turnover decisions, as does receiving lower compensation relative to the market.     

Changing Their Minds: Enhancing Poststroke Occupational Performance Using Transcranial Direct Current Stimulation

Stroke remains a leading cause of disability, with survivors experiencing long-term decrements in independence and quality of life. Occupational therapists (OTs) employ numerous neurorehabilitative treatment approaches to remediate impairments that are impeding performance. OTs also use physical agent modalities to facilitate increased participation and success in therapy. One such modality is transcranial direct current stimulation (tDCS), a form a noninvasive brain stimulation that can be overlaid onto task practice and delivers a constant, low intensity current into the brain. tDCS is safe, portable, and efficacious in remediating a variety of deficits, yet is not consistently incorporated into clinical practice. The authors discuss the mechanisms, safety, evidence, and potential applications of tDCS to enhance outcomes for this growing population.     

Listeners influence speakers’ perceived communication effectiveness

People have an exaggerated sense of self-efficacy. This paper investigates the mechanism behind speakers’ tendency to overestimate their communication efficacy. Two competing mechanisms were tested: intrapersonal and interpersonal. Speakers communicated a series of ambiguous statements to a co-present or absent listener and then estimated their success. Speakers overestimated their ability to communicate their intended message (relative to listeners’ actual comprehension of their message) when a listener was co-present, but not when a listener was absent. Our findings support an interpersonal explanation of speakers’ perceived communication efficacy.     

The transmission of support: a Bayesian re-analysis

Crispin Wright’s discussion of the notion of ‘transmission-failure’ promises to have important philosophical ramifications, both in epistemology and beyond. This paper offers a precise, formal characterisation of the concept within a Bayesian framework. The interpretation given avoids the serious shortcomings of a recent alternative proposal due to Samir Okasha.