Cognitive Function in Parkinson's Disease: Association with Anxiety but Not Depression

To reexamine the relationships of depression, anxiety and cognitive impairment in Parkinson's disease (PD), 27 patients with idiopathic PD received two measures of depression, the State-Trait Anxiety Inventory, and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Contrary to some earlier studies, measures of depression, even those that separated mood from somatic symptoms, were not correlated with any measure of cognitive performance. By contrast, measures of anxiety were signifiantly and negatively correlated with all RBANS indexes. Because anxiety and depression are partially overlapping psychiatric disorders, inconsistent reports concerning the relationship of depression and cognition in PD may have arisen because different studies included varying proportions of depressed patients who were also highly anxious.     

Relating inter-individual differences in metacognitive performance on different perceptual tasks

Human behavior depends on the ability to effectively introspect about our performance. For simple perceptual decisions, this introspective or metacognitive ability varies substantially across individuals and is correlated with the structure of focal areas in prefrontal cortex. This raises the possibility that the ability to introspect about different perceptual decisions might be mediated by a common cognitive process. To test this hypothesis, we examined whether inter-individual differences in metacognitive ability were correlated across two different perceptual tasks where individuals made judgments about different and unrelated visual stimulus properties. We found that inter-individual differences were strongly correlated between the two tasks for metacognitive ability but not objective performance. Such stability of an individual’s metacognitive ability across different perceptual tasks indicates a general mechanism supporting metacognition independent of the specific task.     

Comparing the temporal stability of self-report and interview assessed personality disorder

Findings from several large-scale, longitudinal studies over the last decade have challenged the long-held assumption that personality disorders (PDs) are stable and enduring. However, the findings, including those from the Collaborative Longitudinal Personality Disorders Study (CLPS; Gunderson et al., 2000), rely primarily on results from semistructured interviews. As a result, less is known about the stability of PD scores from self-report questionnaires, which differ from interviews in important ways (e.g., source of the ratings, item development, and instrument length) that might increase temporal stability. The current study directly compared the stability of the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV) PD constructs assessed via the Schedule for Nonadaptive and Adaptive Personality (SNAP-2; Clark, Simms, Wu, & Casillas, in press) with those from the Diagnostic Interview for DSM-IV Personality Disorders (Zanarini, Frankenburg, Sickel, & Yong, 1996) over 2 years in a sample of 529 CLPS participants. Specifically, we compared dimensional and categorical representations from both measures in terms of rank-order and mean-level stability. Results indicated that the dimensional scores from the self-report questionnaire had significantly greater rank-order (mean r=.69 vs. .59) and mean-level (mean d=0.21 vs. 0.30) stability. In contrast, categorical diagnoses from the two measures evinced comparable rank-order (mean κ=.38 vs. .37) and mean-level stability (median prevalence rate decrease of 3.5% vs. 5.6%). These findings suggest the stability of PD constructs depends at least partially on the method of assessment and are discussed in the context of previous research and future conceptualizations of personality pathology.     

Auditory mismatch negativity: detecting spectral contrasts in a modulated noise

The ability to detect sinusoidal spectral envelope from an unmodulated (flat) spectrum has shown a strong correlation with speech perception in quiet and noisy listening conditions in normal hearing, hearing-impaired, and cochlear implant users. In this study, the mismatch negativity (MMN) was collected from 10 normal-hearing adult listeners and used to determine if modulation detection thresholds derived electrophysiologically correlate with the psychophysically measured spectral modulation detection thresholds. MMNs were present for most participants with spectral contrasts of 10 and 20 dB, suggesting that the MMN may be a promising neurophysiologic measure of spectral envelope perception when nonbehavioral measures are desired.     

Context-outcome associations mediate context-switch effects in a human predictive learning task

Four experiments explored the role of contexts in information retrieval after different levels of acquisition training in human predictive learning. Participants were trained where cue (X) was followed by an outcome in context A while a different cue (Y) was followed by the absence of the outcome in context B. When 4 training trials with each cue were conducted, testing the stimuli in the alternative contexts decreased predictive judgments to X and increased predictive judgments to Y. These effects disappeared both when training was increased up to 18 trials (Experiments 1a and 1b), and when the outcome was presented in both contexts A and B (Experiments 2 and 4). When the outcome was presented in both contexts, the nonreinforced cue Y, trained in the presumably excitatory context B, became a conditioned inhibitor (Experiment 3). Additional experience with one of the contexts, but not with both, made the context-switch effect reappear (Experiment 4). These results suggest that irrelevant contexts may enter into direct associations with the outcome before prolonged training leads participants to discard them as predictors.     

Assessing personality in the DSM-5: the utility of bipolar constructs

All previous editions of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM) have described and assessed personality solely in terms of pathological categories. Nonetheless, there is compelling evidence that normal-range personality traits also provide clinically useful information, emphasizing the importance of thoroughly assessing both adaptive and maladaptive aspects of personality within a clinical context. The proposed inclusion of a dimensional trait model in the upcoming DSM-5 represents an important shift in the understanding of personality pathology and provides an ideal opportunity to integrate the assessment of normal personality into clinical practice. Building on research conceptualizing personality disorders as maladaptive, extreme variants of general personality traits, it is proposed that both normal and abnormal personality can be assessed within the same dimensional model using bipolar constructs. The inclusion of bipolar traits, such as a continuum ranging from introversion to extraversion, would hold numerous advantages for a dimensional model. These benefits include a strong foundation of existing validity research, comprehensive coverage of personality pathology, and the ability to provide useful information about all individuals. Despite potential complexities, the adoption of bipolar constructs within DSM-5's dimensional model presents the greatest opportunity to maximize efficiency, validity, and clinical utility.     

Perceptual learning evidence for contextually-specific representations

Listeners rapidly adjust to talkers’ pronunciations, accommodating those pronunciations into the relevant phonemic category to improve subsequent perception. Previous work has suggested that such learning is restricted to pronunciations that are representative of how the speaker talks (Kraljic, Samuel, & Brennan, 2008). If an ambiguous pronunciation, for example, can be attributed to an external source (such as a pen in the speaker’s mouth), or if it is preceded by normal pronunciations of the same sound, learning is blocked.In three experiments, we explore this blocking effect in more detail. Our aim is to better understand the nature of the representations underlying the perceptual learning process. Experiment 1 replicates the blocking effect. Experiments 2 and 3 demonstrate that it can be eliminated when certain visual information occurs simultaneously with the auditory signal. The pattern of learning and non-learning is best accounted for by the view that speech perception is mediated by episodic representations that include potentially relevant visual information.     

Leadership and management research in Africa: A synthesis and suggestions for future research

Although we are aware of some positive cases of leadership and management emerging on the African continent, very little empirical or theoretical work has addressed leadership and management in Africa. This raises a challenge for African nations in that ultimately a country's economic performance is contingent on the effectiveness of its leadership and management practices that serve to unlock the potential of its workforce to effectively implement the strategic goals of organizations. Against the backdrop of an increasingly knowledge‐dependent global marketplace, the centrality of leadership and effective management systems as drivers of individual and organization performance has never been more critical. This special section brings together a compendium of papers that advances the science of leadership and management within the African context. Our principle goal was to examine what is unique, what generalizes, and what does not generalize from the West and East to Africa, as well as within different regions of Africa and then offer ideas to guide future research and practice. The papers in this section provide a broad and indeed innovative approach to studying leadership and management in Africa by including historical, philosophical, economic, and socio‐political perspectives, as part of the analyses of leadership and management in the African context. Our editorial provides an integration of this work and a launching point for some audacious goals for future leadership and management science and practice in Africa and beyond.