A meta-analytic investigation of the structure of posttraumatic stress disorder symptoms.

Converging lines of evidence have called into question the validity of conceptualizations of posttraumatic stress disorder (PTSD) based on the Diagnostic and Statistical Manual of Mental Disorders (DSM; American Psychiatric Association, 2000) and suggested alternative structural models of PTSD symptomatology. We conducted a meta-analysis of 40 PTSD studies (N = 14,827 participants across studies) that used a DSM-based measure to assess PTSD severity. We aggregated correlation matrices across studies and then applied confirmatory factor analysis to the aggregated matrices to test the fit of competing models of PTSD symptomatology that have gained support in the literature. Results indicated that both prominent 4-factor models of PTSD symptomatology yielded good model fit across subsamples of studies; however, the model comprising Intrusions, Avoidance, Hyperarousal, and Dysphoria factors appeared to fit better across studies. Results also indicated that the best fitting models were not moderated by measure or sample type. Results are discussed in the context of structural models of PTSD and implications for the diagnostic nosology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Study of the structurization kinetics in hardening dispersion systems by the internal friction method

An experimental study was made concerning changes in the internal friction in a disperse material during hardening and the effect of the initial solid-to-liquid contents ratio on the structurization process.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 6, pp. 1068–1073, June, 1973.     

A methodology for studying cognitive groupings in a target-trackingtask

In the present research, a special form of cluster analysis was successful in revealing cognitive groupings having appreciable influence on task performance in a target-tracking task designed to resemble ATC. The method of cluster analysis was derived from the “virtual associative network” model of memory organization and applied to the record of eye fixations in the course of task performance. Results using inexperienced subjects showed fixation clustering consistent with Gestalt factors. Task objectives did not seem to affect grouping as much. The subjects' recall was generally poor, except where direct manipulation of targets occurred. We conclude that: 1) cognitive grouping influences performance; 2) recall techniques may not be able to elicit subjects' cognitive groupings; and 3) such groupings can be determined via analysis of eye fixations. These findings have implications for studying workload assessment and information structuring in complex visual scanning tasks     

Swiss army knife and Ockham's razor: modeling and facilitating operator's comprehension in complex dynamic tasks

This paper identifies two contending metaphors of the mind, and outlines a model of comprehension informed by the parsimony principle ("Ockham's razor"). The model, called virtual associative network (VAN), is applied to explain human performance and improve decision aiding in complex tasks involving multiple variables and rapidly changing constraints. This model is compared to a conventional modeling paradigm ("Swiss army knife") representing the mind as a "toolkit" of special purpose "instruments" (or modules). The paper has four sections. The first section introduces the VAN model focusing on its key assumptions. The second section runs computational experiments to assess the mathematical validity of these assumptions. Next, some of the model's decision aiding applications are demonstrated. The concluding section discusses agreement and the lack of such between the VAN model and other cognitive theories. Discussion centers on assessing VAN's plausibility vis-a-vis recent neuropsychological findings.