The time course of task switching: A speed—accuracy trade-off analysis

On each trial of this study, participants either switched between or repeated two simple, two-choice tasks involving either letter or digit classifications. Speed-accuracy trade-off (SAT) curves were obtained using the responsesignal method of eliciting speeded responses at various response time lags after the presentation of the stimulus for the second task. The key finding from separate analyses of the three SAT-curve parameters (intercept, rate, and asymp tote) was that the location of the intercept of the SAT function (i.e., the point at which responding rises above chance) was shifted upward for both short and long response-stimulus intervals under task-switch conditions but only when the responses associated with each of the letter-digit stimulus components were incompatible.     

The Disgust Scale: item analysis, factor structure, and suggestions for refinement

In the 4 studies presented (N = 1,939), a converging set of analyses was conducted to evaluate the item adequacy, factor structure, reliability, and validity of the Disgust Scale (DS; J. Haidt, C. McCauley, & P. Rozin, 1994). The results suggest that 7 items (i.e., Items 2, 7, 8, 21, 23, 24, and 25) should be considered for removal from the DS. Secondary to removing the items, exploratory and confirmatory factor analyses revealed that the DS taps 3 dimensions of disgust: Core Disgust, Animal Reminder Disgust, and Contamination-Based Disgust. Women scored higher than men on the 3 disgust dimensions. Structural modeling provided support for the specificity of the 3-factor model, as Core Disgust and Contamination-Based Disgust were significantly predictive of obsessive- compulsive disorder (OCD) concerns, whereas Animal Reminder Disgust was not. Results from a clinical sample indicated that patients with OCD washing concerns scored significantly higher than patients with OCD without washing concerns on both Core Disgust and Contamination-Based Disgust, but not on Animal Reminder Disgust. These findings are discussed in the context of the refinement of the DS to promote a more psychometrically sound assessment of disgust sensitivity.     

Overcoming interference: an fMRI investigation of pattern separation in the medial temporal lobe

The medial temporal lobe (MTL) supports the formation and retrieval of long-term declarative memories, or memories for facts and everyday events. One challenge posed for this type of memory stems from the highly overlapping nature of common episodes. Within cognitive psychology, it is widely accepted that interference between information learned at different times is a major limitation on memory. In spite of several decades of intense research in the fields of interference theory and the neurobiological underpinnings of declarative memory, there is little direct evidence bearing on how the MTL resolves this interference to form accurate memories of everyday facts and events. Computational models of MTL function have proposed a mechanism in which the MTL, specifically the hippocampus, performs pattern separation, whereby overlapping representations are made less similar. However, there is little evidence bearing on how this process is carried out in the intact human MTL. Using high-resolution fMRI, we conducted a set of experiments that taxed behavioral pattern separation by using highly similar, interfering stimuli in a modified continuous recognition task. Regions within the parahippocampal gyrus demonstrated activity consistent with a "recall to reject" strategy. In contrast and critical to performing the task, activity within the hippocampus distinguished between correctly identified true stimulus repetitions, correctly rejected presentations of similar lure stimuli, and false alarms to similar lures. These data support the computational models' assertion that the hippocampus plays a key role in pattern separation.     

Score Metric Equivalence of the Psychopathy Checklist-Revised (PCL-R) across criminal offenders in North America and the United Kingdom: a critique of Cooke, Michie, Hart, and Clark (2005) and new analyses

David Cooke and colleagues have published a series of item response theory (IRT) studies investigating the equivalence of the Psychopathy Checklist-Revised (PCL-R) for European versus North American (NA) male criminal offenders. They have consistently concluded that PCL-R scores are not equivalent, with European offenders receiving scores up to five points lower than those in NA when matched according to the latent trait. In this article, the authors critique the Cooke et al. analyses and demonstrate how their anchor item selection method is responsible for their final conclusions concerning the apparent lack of equivalence. The authors provide a competing IRT analysis using an iterative purification strategy for anchor item selection and show how this more justifiable approach leads to very different conclusions regarding the equivalence of the PCL-R. More generally, it is argued that strong interpretations of IRT analyses in the presence of uncorroborated anchor items can be highly misleading when evaluating score metric equivalence.     

Hyperperfusion syndromes: insight into the pathophysiology and treatment of hypertensive encephalopathy

Hypertensive encephalopathy is one of the manifestations of a hypertensive crisis. It is not the absolute value of the blood pressure that causes the encephalopathy, rather the presence of an abrupt rise in pressure. In terms of clinical and radiographic findings, there are many similarities among a group of entities, including hypertensive encephalopathy, eclampsia, and immunosuppressant neurotoxicity. Hyperperfusion syndromes may represent these clinical disease states that may share the same pathophysiology. Magnetic resonance imaging fluid attenuated inversion recovery sequences have recognized the prominent cortical involvement of the disease that had been previously missed on computed tomography. Studies have found cortical involvement in 94% of their patients, particularly in mild cases. Animal models demonstrate endothelial damage and enhanced pinocytosis in the cortex as reasons why edema may begin in that region of the brain. Patients diagnosed with hypertensive encephalopathy should be diagnosed and treated promptly in order to avoid further neurological complications. The mean arterial pressure should be lowered by 20% to 25% within the first hour of patient presentation, followed by further gradual reduction in blood pressure over the following 24 hours. Hypertensive emergency in acute ischemic stroke should be managed with more caution. According to the 2003 American Stroke Association treatment guidelines, for patients with ischemic stroke not eligible for thrombolytic therapy, target blood pressures are a diastolic blood pressure <120 mmHg and systolic blood pressure <220 mmHg. The systolic pressure must be <185 mmHg and diastolic pressure <110 mmHg at all times if eligible for thrombolytic therapy.     

A year of unprecedented progress in Down syndrome basic research

The years 2006 and 2007 saw the publication of three new and different approaches to prevention or amelioration of Down syndrome effects on the brain and cognition. We describe the animal model systems that were critical to this progress, review these independent breakthrough studies, and discuss the implications for therapeutic approaches suggested by each.     

Pathways from proactive and reactive aggression to substance use.

Childhood aggression is a known risk factor for adolescent substance use; however, aggression is a complex construct, and developmental researchers have identified a variety of subdimensions that may be germane to substance use. Very little research has examined risk pathways from subdimensions of aggression. The current study examined a developmental model and tested whether childhood proactive aggression, reactive aggression, or both were related to the development of substance use in adolescence in a sample of 126 children (mean age at initial assessment = 10.4 years, SD = 0.51). Peer rejection and peer delinquency were examined as potential mediators of these relations. The findings suggest that proactive aggression was indirectly associated with substance use through peer delinquency. Reactive aggression was also indirectly associated with substance use through a complex mediational chain, such that high levels of reactive aggression were associated with high levels of peer rejection, which in turn were associated with peer delinquency (p = .06), which subsequently predicted substance use.     

Development of a global measure of job embeddedness and integration into a traditional model of voluntary turnover

Recent research on job embeddedness has found that both on- and off-the-job forces can act to bind people to their jobs. The present study extended this line of research by examining how job embeddedness may be integrated into a traditional model of voluntary turnover. This study also developed and tested a global, reflective measure of job embeddedness that overcomes important limitations and serves as a companion to the original composite measure. Results of this longitudinal study found that job embeddedness predicted voluntary turnover beyond job attitudes and core variables from traditional models of turnover. Results also found that job embeddedness interacted with job satisfaction to predict voluntary turnover, suggesting that the job embeddedness construct extends beyond the unfolding model of turnover (T. R. Mitchell & T. W. Lee, 2001) it originated from.