Long term course of chronic posttraumatic stress disorder in traffic accident victims: a three-year prospective follow-up study

The purpose of the present study was to gather prospective longitudinal data on the long-term course and outcome of chronic posttraumatic stress disorder (PTSD). The target population for this study was 74 injured traffic accident victims who had been previously followed-up for one year after the trauma. Nineteen of the original 24 PTSD subjects (79%) and 39 of the original 50 Non-PTSD subjects (78%) were available for this study, which took place during the fourth year after the accident. Our results show that 10 (53%) of the 19 patients with PTSD at one-year still suffered from PTSD after another two-year follow-up interval, while 9 recovered from PTSD during this follow-up period. Only 2 of the 39 without PTSD at one year developed delayed onset PTSD. The best predictor of recovery from chronic PTSD was the initial level of posttraumatic reaction immediately after the accident. These results demonstrate that spontaneous recovery from PTSD can occur even among patients who are currently considered chronic. Severity of initial reaction to the trauma appears to be a major risk factor for non-remitting chronic PTSD.     

Modulation of the attentional blink by differential resource allocation.

When one masked target (T2) follows another (T1) in close temporal proximity, identification accuracy of the second target is reduced for a period referred to as the attentional blink. Analysis of the attentional blink literature suggests that increasing the difficulty of T1 processing increases the magnitude of the blink. In a previous study that eliminated several untoward features of the typical attentional blink design (e.g., task switching, location switching, and stream contribution), we found no effect on blink magnitude when three levels of T1 difficulty (manipulated in a data-limited manner) were randomly intermixed. Here, when we repeated the previous study using a blocked manipulation of T1 difficulty, which is characteristic of the literature, a significant positive relation between T1 difficulty and blink magnitude was found. Resource allocation put in place to encode T1 in advance of a dual-target trial thus seems to be the critical factor in mediating this relation.     

Measuring, estimating, and understanding the psychometric function: A commentary

The psychometric function, relating the subject’s response to the physical stimulus, is fundamental to psychophysics. This paper examines various psychometric function topics, many inspired by this special symposium issue ofPerception & Psychophysics: What are the relative merits of objective yes/no versus forced choice tasks (including threshold variance)? What are the relative merits of adaptive versus constant stimuli methods? What are the relative merits of likelihood versus up-down staircase adaptive methods? Is 2AFC free of substantial bias? Is there no efficient adaptive method for objective yes/no tasks? Should adaptive methods aim for 90% correct? Can adding more responses to forced choice and objective yes/no tasks reduce the threshold variance? What is the best way to deal with lapses? How is the Weibull function intimately related to thed’ function? What causes bias in the likelihood goodness-of-fit? What causes bias in slope estimates from adaptive methods? How good are nonparametric methods for estimating psychometric function parameters? Of what value is the psychometric function slope? How are various psychometric functions related to each other? The resolution of many of these issues is surprising.     

The Contribution of Attributional Style to Perceived Disability in Rheumatoid Arthritis: A Longitudinal Study

The current study investigated the influence of general causal attributions on self-reported physical disability over the course of 1 year in a sample of 42 patients with rheumatoid arthritis (RA). Participants completed measures of attributional style, pain, and disability; physician assistants completed objective measures of disability on two occasions, approximately 1 year apart. Results indicated that internal attributions for disease-unrelated negative events assessed at Time 1 were associated with lower perceived physical disability, whereas stable attributions for negative events were associated with greater perceived physical disability 1 year later. These findings are discussed in terms of behavioral and characterological self-blame models, respectively. Implications of our findings for clinical management of RA are also discussed.     

Maximum likelihood estimation of latent interaction effects with the LMS method

In the context of structural equation modeling, a general interaction model with multiple latent interaction effects is introduced. A stochastic analysis represents the nonnormal distribution of the joint indicator vector as a finite mixture of normal distributions. The Latent Moderated Structural Equations (LMS) approach is a new method developed for the analysis of the general interaction model that utilizes the mixture distribution and provides a ML estimation of model parameters by adapting the EM algorithm. The finite sample properties and the robustness of LMS are discussed. Finally, the applicability of the new method is illustrated by an empirical example. This research has been supported by a grant from the Deutsche Forschungsgemeinschaft, Germany, No. Mo 474/1 and Mo 474/2. The data for the empirical example have been provided by Andreas Thiele of the University of Frankfurt, Germany. The authors are indebted to an associate editor and to three anonymous reviewers ofPsychometrika whose comments and suggestions have been very helpful.     

REDUCTION WITHOUT REDUCTIONISM: A DEFENCE OF NAGEL ON CONNECTABILITY

Unlike the overall framework of Ernest Nagel's work on reduction, his theory of intertheoretic connection still has life in it. It handles aptly cases where reduction requires complex representation of a target domain. Abandoning his formulation as too liberal was a mistake. Arguments that it is too liberal at best touch only Nagel's deductivist theory of explanation, not his condition of connectability. Taking this condition seriously gives a powerful view of reduction, but one which requires us to index explanatory power to sciences as they are formulated at particular times. While we may thereby reduce more than philosophers have supposed, we must abandon hope (as Nagel did) of saying anything useful about reductionism.     

The exact vs. approximate distinction in numerical cognition may not be exact, but only approximate: How different processes work together in multi-digit addition

Two types of calculation processes have been distinguished in the literature: approximate processes are supposed to rely heavily on the non-verbal quantity system, whereas exact processes are assumed to crucially involve the verbal system. These two calculation processes were commonly distinguished by manipulation of two factors in addition problems: the identity of the target and the distance of the distractor. However, in all previous studies, these two factors were not manipulated independently. In this fMRI study, we could disentangle the two factors by using a different (two-digit) number stimulus set. Both behavioral and neurofunctional data suggest that the cognitive processes involved could be best explained by the (independent) factors target and distractor distance. Based on these data we suggest that the exact/approximate distinction does not seem to be as generally valid as previously assumed. We conclude that this study may be a starting point for a closer examination of the experimental, procedural and strategic conditions of when the exact/approximate distinction is valid and when it is not.     

Brain regions as difference-makers

Contrastive neuroimaging is often taken to provide evidence about the localization of cognitive functions. After canvassing some problems with this approach, I offer an alternative: neuroimaging gives evidence about regions of the brain that bear difference-making relationships to psychological processes of interest. I distinguish between the specificity and what I call the systematicity of a difference-making relationship, and I show how at least some neuroimaging experiments can give evidence for systematic difference-making.     

Improving the quality of parental interaction with very low birth weight children: A longitudinal study using a Mediated Learning Experience model

Cognitive performance of 3-year-old, very low birth weight children (N = 42) was found to be more significantly related to the quality of parent-child interaction than to early measures of cognitive performance or measures of developmental risk such as birth weight and APGAR. The subjects were randomly divided into an intervention and a control group. The intervention group was visited at home, infrequently, by a mediator who identified basic criteria of quality of parent-child interaction and provided the parents with feedback on the quality of interaction with their own children. The intervention procedure continued for 7 months. The extent of a family's participation in the intervention varied depending upon the initial quality of parent-child interaction and the amount of time it took a family to reach criteria. Quality of parent-child interaction and children's cognitive performance were pretested and reassessed 3 years after the intervention. The sample was reduced to 29 due to attrition over time. Parental behavior following the intervention had changed significantly with respect to all criteria. Parents who had received intervention, as compared to the control group parents, provided their children with more behaviors related to focusing attention, exciting and rewarding, expanding children's understanding of the world around them, preplanning and regulating behavior. Three years after the relatively unintensive intervention, parents continued to show significant gains in quality of mediation. Differences were found between parents of Small for Gestational Age (SGA) and Appropriate for Gestational Age (AGA) children in favor of the SGA group. In children's cognitive performance, scores of the intervention group on the Peabody Picture Vocabulary Test (PPVT) were significantly higher than those of the control group. On other cognitive measures, a consistent trend in favor of the intervention group was noted. More children in the control as compared to the experimental group were rated by their parents as having difficulties with language, fine motor, and sociability skills 3 years after the intervention.