Etiology of strokes in children with sickle cell anemia

The most devastating complication of sickle cell anemia is cerebral infarction, affecting approximately 30% of all individuals with sickle cell anemia. Despite being one of the most common causes of stroke in infants and children, the mechanism of cerebral infarction in this population has not been extensively studied and is poorly understood. Multiple, synergistic factors are important in the pathogenesis of stroke including the hemodynamic effects of cerebral arterial occlusive disease, viscosity, chronic and acute anemia and acute medical events. This review focuses on the relationship between these factors in order to provide a foundation for further study of the etiology of strokes in this high-risk population.     

Magnitude of cerebral asymmetry at rest: covariation with baseline cardiovascular activity

The cerebral regulation of cardiovascular functioning varies along both a lateral and a longitudinal axis. The parasympathetic and sympathetic nervous systems are lateralized to the left and right cerebral hemispheres, respectively. Further, the frontal lobes are known to be inhibitory in nature, whereas the temporal lobes are excitatory. However, no systematic investigation has been conducted to determine the nature and strength of the relationship between the left and right frontal and temporal lobes in regulating cardiovascular activity. The present investigation sought to examine these relationships by testing the hypothesis that negative correlations would be found between baseline heart rate and blood pressure and asymmetry of alpha magnitude across the frontal lobes. Further, positive correlations were hypothesized to exist across the temporal lobes. A total of 20 women were asked to relax with their eyes closed while heart rate and blood pressure as well as quantitative electroencephalography data were obtained. The results indicated that, as hypothesized, significant negative correlations existed across the frontal lobes and significant positive correlations existed across the temporal lobes. The results provide further support for a division of responsibility between the left and right frontal and temporal lobes in the regulation of heart rate and blood pressure.     

Facilitated cognitive disengagement in depression

The present study was conducted to test predictions derived from the hypothesis that depression may serve the purpose of adaptively facilitating disengagement from obsolete cognitive plans. Groups of students with either low or high depression scores were contrasted using a procedure that featured an initial learning phase, within which participants learned to perform a task, followed by a relearning phase within which they needed to disengage from initial learning in order to relearn to perform an altered task. It was assumed that performance in the relearning phase would be affected by the degree to which participants could readily disengage from their initial learning. As predicted, participants in the high depression group, relative to those in the low depression group, demonstrated superior performance in the relearning phase alone. The theoretical and applied implications of this finding are discussed.     

Withholding inputs in team contexts: member composition, interaction processes, evaluation structure, and social loafing

Social loafing was observed as a naturally occurring process in project teams of students working together for 3-4 months. The authors assessed the contributions that member composition (i.e., relational dissimilarity and knowledge, skills, and abilities; KSAs), perceptions of the team's interaction processes (i.e., dispensability and the fairness of the decision-making procedures), and the team's evaluation structure (i.e., identifiability) make toward understanding loafing behavior. Identifiability moderated the impact of dispensability on loafing but not the impact of fairness on loafing. Perceptions of fairness were negatively related to the extent that participants loafed within their team. Specific aspects of relational dissimilarity were positively associated with perceptions of dispensability and negatively associated with perceptions of fairness, whereas KSAs were negatively associated with perceptions of dispensability.     

The MMPI-2 Restructured Clinical Scales: a paradigmatic shift in scale development

Tellegen et al. (2003) proposed fundamental changes in MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) scale development by discarding empirical scale development in favor of construct validation via Jackson's (1970) sequential system of scale development. As a result of their efforts, a general distress factor (Demoralization) was identified and 8 Restructured Clinical (RC) Scales were developed. Using 7,330 clinical cases from Caldwell's (1997) data set, in this study, we sought to cross-validate the MMPI-2 RC Scales. Scale homogeneity was confirmed with high alpha coefficients and interitem correlations in the expected range. We also achieved a major objective of reducing interscale correlations. In replicating Tellegen et al.'s principal components analysis, we achieved a high concordance for 6 of the 8 RC Scales. We critically examine these results in light of Jackson's construct validation. We discuss the clinical usefulness of the MMPI-2 RC Scales within the context of current and future research.     

Does group efficacy increase group identification? Resolving their paradoxical relationship

Although group identification and group efficacy are both important predictors of collective action against collective disadvantage, there is mixed evidence for their (causal) relationship. Meta-analytic and correlational evidence suggests an overall positive relationship that has been interpreted as consistent with the idea that group identification leads to group efficacy. However, experimental evidence has not supported this causal relationship. To resolve this paradox, we show in an experiment that it is group efficacy that leads to increased group identification because group efficacy puts individuals' identity into action. We discuss the theoretical and practical implications of these findings.     

Morphemes in their place: Evidence for position-specific identification of suffixes

Previous research strongly suggests that morphologically complex words are recognized in terms of their constituent morphemes. A question thus arises as to how the recognition system codes for morpheme position within words, given that it needs to distinguish morphological anagrams like overhang and hangover. The present study focused specifically on whether the recognition of suffixes occurs in a position-specific fashion. Experiments 1 and 2 revealed that morphologically complex nonwords (gasful ) are rejected more slowly than orthographic controls (gasfil ) but that the same interference effect is not present when the morphemic constituents are reversed ( fulgas vs. filgas). Experiment 3 went further in demonstrating that reversing the morphemes within words (e.g., nesskind) does not yield morpheme interference effects against orthographic controls (e.g., nusskind). These results strongly suggest that suffix identification is position specific, which imposes important constraints on the further development of models of morphological processing.     

A Challenge for Soft Line Replies to Manipulation Cases

Cases involving certain kinds of manipulation seem to challenge compatibilism about responsibility-grounding free will. To deal with such cases many compatibilists give what has become known as a ‘soft line’ reply. In this paper I present a challenge to the soft line reply. I argue that any relevant case involving manipulation—and to which a compatibilist might wish to give a soft line reply—can be transformed into one supporting a degree of moral responsibility through the addition of libertarian elements (such as alternative possibilities of a kind unavailable under determinism and executive control of the sort commonly associated with agent-causation). From a compatibilist’s perspective the subtraction of libertarian elements should make no difference to any assessment of the agent’s responsibility. The compatibilist should therefore judge the agent morally responsible after the removal of the libertarian elements. Yet removal of the libertarian elements returns the case to its original form and thus what started out as a soft line has now collapsed into a hard line reply. Various ways of resisting my argument are considered, but each is shown to carry important burdens.     

Remembered study mode: Support for the distinctiveness account of the production effect

The production effect is the finding that words spoken aloud at study are subsequently remembered better than are words read silently at study. According to the distinctiveness account, aloud words are remembered better because the act of speaking those words aloud is encoded and later recovery of this information can be used to infer that those words were studied. An alternative account (the strength-based account) is that memory strength is simply greater for words read aloud. To discriminate these two accounts, we investigated study mode judgements (i.e., “aloud”/”silent”/”new” ratings): The strength-based account predicts that “aloud” responses should positively correlate with memory strength, whereas the distinctiveness account predicts that accuracy of study mode judgements will be independent of memory strength. Across three experiments, where the strength of some silent words was increased by repetition, study mode was discriminable regardless of strength—even when the strength of aloud and repeated silent items was equivalent. Consistent with the distinctiveness account, we conclude that memory for “aloudness” is independent of memory strength and a likely candidate to explain the production effect.