The Heteroscedastic Graded Response Model with a Skewed Latent Trait: Testing Statistical and Substantive Hypotheses Related to Skewed Item Category Functions

The Graded Response Model (GRM; Samejima, Estimation of ability using a response pattern of graded scores, Psychometric Monograph No.?17, Richmond, VA: The Psychometric Society, 1969) can be derived by assuming a linear regression of a continuous variable, Z, on the trait, ??, to underlie the ordinal item scores (Takane & de Leeuw in Psychometrika, 52:393?C408, 1987). Traditionally, a normal distribution is specified for Z implying homoscedastic error variances and a normally distributed ??. In this paper, we present the Heteroscedastic GRM with Skewed Latent Trait, which extends the traditional GRM by incorporation of heteroscedastic error variances and a skew-normal latent trait. An appealing property of the extended GRM is that it includes the traditional GRM as a special case. This enables specific tests on the normality assumption of Z. We show how violations of normality in Z can lead to asymmetrical category response functions. The ability to test this normality assumption is beneficial from both a statistical and substantive perspective. In a simulation study, we show the viability of the model and investigate the specificity of the effects. We apply the model to a dataset on affect and a dataset on alexithymia.     

Neuropsychological Sequelae of PTSD and TBI Following War Deployment among OEF/OIF Veterans

Posttraumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) are highly prevalent among Veterans of the conflicts in Iraq and Afghanistan. These conditions are associated with common and unique neuropsychological and neuroanatomical changes. This review synthesizes neuropsychological and neuroimaging studies for both of these disorders and studies examining their co-occurrence. Recommendations for future research, including use of combined neuropsychological and advanced neuroimaging techniques to study these disorders alone and in concert, are presented. It is clear from the dearth of literature that addiitonal studies are required to examine and understand the impact of specific factors on neurocognitive outcome. Of particular relevance are temporal relationships between PTSD and mTBI, risk and resilience factors associated with both disorders and their co-occurrence, and mTBI-specific factors such as time since injury and severity of injury, utilizing comprehensive, yet targeted cognitive tasks.     

Shared Decision-Making Among Caregivers and Health Care Providers of Youth with Type 1 Diabetes

The present study aimed to examine perceptions of shared decision-making (SDM) in caregivers of youth with type 1 diabetes (T1D). Interview, survey data, and HbA1c assays were gathered from caregivers of 439 youth with T1D aged 3–18 years. Caregiver-report indicated high perceived SDM during medical visits. Multivariable linear regression indicated that greater SDM is associated with lower HbA1c, older child age, and having a pediatric endocrinologist provider. Multiple logistic regression found that caregivers who did not perceive having made any healthcare decisions in the past year were more likely to identify a non-pediatric endocrinologist provider and to report less optimal diabetes self-care. Findings suggest that youth whose caregivers report greater SDM may show benefits in terms of self-care and glycemic control. Future research should examine the role of youth in SDM and how best to identify youth and families with low SDM in order to improve care.     

The Coping Paradox: Work,Stress, and Coping in the U.S. Army

The military environment has unique stressors. This study investigates the types of stressors, appraisals, and coping responses of U.S. soldiers and their leaders. A qualitative analysis of interviews indicates that the traditional coping buffers of social drinking and seeking social support from fellow soldiers, family, and leaders can potentially serve as sources of stress. While this paradox may be a result of the unique types of stressors in the military work environment, these results should direct researchers to better understand individuals' perceptions and appraisals of stress, with a focus on the meaning of stress, given contextual factors inherent in the workplace. The findings are discussed in relation to the literature on the impact of stress on physical and psychological health.     

Part-set cuing effects in younger and older adults

In 3 experiments, the authors examined part-set cuing effects in younger and older adults. Participants heard lists of category exemplars and later recalled them. Recall was uncued or cued with a subset of studied items. In Experiment 1, participants were cued with some of the category names, and they remembered fewer never-cued categories than a free-recall condition. In Experiment 2, a similar effect was observed for category exemplar cues. There was also an age difference: By some measures, a small number of cues impaired older adults more than younger. Experiment 3 replicated this result and found that older adults were disproportionately slow in the presence of cues. Across experiments, older adults showed robust part-set cuing effects, and sometimes, they were disproportionately impaired by cues.     

A dynamical model of general intelligence: the positive manifold of intelligence by mutualism

Scores on cognitive tasks used in intelligence tests correlate positively with each other, that is, they display a positive manifold of correlations. The positive manifold is often explained by positing a dominant latent variable, the g factor, associated with a single quantitative cognitive or biological process or capacity. In this article, a new explanation of the positive manifold based on a dynamical model is proposed, in which reciprocal causation or mutualism plays a central role. It is shown that the positive manifold emerges purely by positive beneficial interactions between cognitive processes during development. A single underlying g factor plays no role in the model. The model offers explanations of important findings in intelligence research, such as the hierarchical factor structure of intelligence, the low predictability of intelligence from early childhood performance, the integration/differentiation effect, the increase in heritability of g, and the Jensen effect, and is consistent with current explanations of the Flynn effect.     

Patterns of personality pathology in patients with generalized anxiety disorder, panic disorder with and without agoraphobia, and social phobia

The relationship between co-occurring personality disorders and anxiety disorders (panic disorder with or without agoraphobia, social phobia, and generalized anxiety disorder) was examined, taking into account the effect of major depression. This article describes findings for 622 participants in the Harvard/Brown Anxiety Research Project, a longitudinal follow-up study of DSM-III-R-defined anxiety disorders. A total of 24% of participants had at least one personality disorder, with avoidant, obsessive compulsive, dependent, and borderline most common. Generalized anxiety disorder, social phobia, and major depression were positively associated with the occurrence of one or more personality disorders, whereas panic disorder with agoraphobia was not associated. Major depression was associated in particular with dependent, borderline, histrionic, and obsessive compulsive personality disorders and social phobia was associated with avoidant personality disorder. Whereas some of our findings confirm results from earlier studies, others are somewhat inconsistent with previous results and indicate the need for further investigation.     

Theoretical perspectives on language and communication problems in mental retardation and developmental disabilities

We argue that researchers interested in language and communication problems in mental retardation or any other developmental disorder should view such problems as emerging within the broader context of the behavioral profile, or phenotype, associated with a particular genetic condition. This will require understanding the direct and indirect effects of genes on the development of language and communication and thereby an understanding of the complex relations that exist between language and other dimensions of psychological and behavioral functioning as well as an understanding of the environments in which the developing person acts and is acted upon. We believe that the dominant model for understanding language and communication problems--the nativist approach, which emphasizes the child's innate capacity for acquiring language and characterizes language as consisting of a set of context-free deterministic rules that operate on abstract representations--is inconsistent with an emphasis on indirect genetic effects. We review recent evidence that undermines the nativist approach--evidence concerning the initial state of the language-learning child, the role of environmental input, the competence-performance distinction, and modularity. In place of nativism, we argue for Emergentism, which is a model in which language is seen to emerge from the interaction between the child's biological abilities to map statistical properties of the language input into a distributed representation and the characteristics of the language learning environment and for the purpose of engaging in real-time, meaningful language use.     

Explaining modulation of reasoning by belief

Although deductive reasoning is a closed system, one's beliefs about the world can influence validity judgements. To understand the associated functional neuroanatomy of this belief-bias we studied 14 volunteers using event-related fMRI, as they performed reasoning tasks under neutral, facilitatory and inhibitory belief conditions. We found evidence for the engagement of a left temporal lobe system during belief-based reasoning and a bilateral parietal lobe system during belief-neutral reasoning. Activation of right lateral prefrontal cortex was evident when subjects inhibited a prepotent response associated with belief-bias and correctly completed a logical task, a finding consistent with its putative role in cognitive monitoring. By contrast, when logical reasoning was overcome by belief-bias, there was engagement of ventral medial prefrontal cortex, a region implicated in affective processing. This latter involvement suggests that belief-bias effects in reasoning may be mediated through an influence of emotional processes on reasoning.