Methods for averaging alpha coefficients in reliability generalization studies

The reliability generalization (RG) approach is a kind of meta-analysis that aims to statistically integrate a set of independent reliability coefficients obtained in several applications of a test, with the purpose of characterizing the measurement error and determining which factors related to the studies and samples can explain its variability. Diverse procedures have been proposed in the literature for averaging a set of independent alpha coefficients, and there is no consensus about which methods are best. Here, we present the results of a Monte Carlo simulation study, comparing the performance of twelve procedures proposed in Feldt and Charter, in terms of bias and mean square error. These procedures differ from each other in the transformation (or not) of the coefficients, and in the application or not of a weighting scheme based on sample size. Our results recommend using weighted methods in contrast to unweighted ones, and transforming the coefficients by the Hakstian and Whalen's proposal or by the proposal based on the square root of the inverse alpha coefficient. Lastly, we discuss the relations between the diverse procedures for averaging alpha coefficients with fixed-effects, random-effects, and varying coefficients models.     

Assessing acute stress with the Implicit Association Test

Assessments of acute stress using self-report questionnaires can be biased by various factors, including social desirability. The present study used a bias-free method, the Implicit Association Test (IAT), to assess stress. Unlike a previous study (Schmukle & Egloff, 2004) in which acute stress was not detected with the IAT, this study manipulated stress by generating test anxiety and threatening self-esteem. The results revealed that the IAT effect was greater in the high-stress group than in the low-stress group. Participants in the high-stress group associated their concept of self with the concept of anxiety more strongly than did those in the low-stress group. This result suggests that the IAT is a sensitive measure for detecting group differences in acute stress.     

Mighty metaphors: behavioral and ERP evidence that power shifts attention on a vertical dimension

Thinking about the abstract concept power may automatically activate the spatial up-down image schema (powerful up; powerless down) and consequently direct spatial attention to the image schema-congruent location. Participants indicated whether a word represented a powerful or powerless person (e.g. ‘king’ or ‘servant’). Following each decision, they identified a target at the top or bottom of the visual field. In Experiment 1 participants identified the target faster when their spatial position was congruent with the perceived power of the preceding word than when it was incongruent. In Experiment 2 ERPs showed a higher N1 amplitude for congruent spatial positions. These results support the view that attention is driven to the image schema congruent location of a power word. Thus, power is partially understood in terms of vertical space, which demonstrates that abstract concepts are grounded in sensory-motor processing.     

Dampening of positive affect prospectively predicts depressive symptoms in non-clinical samples

Past research has convincingly shown that a ruminative response style to negative affect (NA) predicts concurrent and prospective levels of depressive symptoms. Recent findings suggest that how people respond to positive affect (PA) might also be involved in the development of depressive symptoms, although this has heretofore not been tested prospectively. Participants from two non-clinical samples (total N=487) completed measures of depressive symptoms, response styles to NA (negative rumination) and response styles to PA (positive rumination and mood dampening) at two assessments separated by a 3-month (Sample 1) and 5-month period (Sample 2). Results in both samples showed that increased dampening responses to PA predict depressive symptoms at follow-up, even when taking into account baseline depressive symptoms and ruminative responses to NA. The results suggest that (dampening) responses to PA add useful information above and beyond (ruminative) responses to NA in predicting depression symptoms prospectively.     

Cumulative estrogen exposure and prospective memory in older women

This study looked at cumulative lifetime estrogen exposure, as estimated with a mathematical index (Index of Cumulative Estrogen Exposure (ICEE)) that included variables (length of time on estrogen therapy, age at menarche and menopause, postmenopausal body mass index, time since menopause, nulliparity and duration of breastfeeding) known to influence estrogen levels across the life span, and performance on prospective and retrospective memory measures in a group of 50 postmenopausal women (mean age=69.3years) who, if they were current or former users of estrogen therapy, had started therapy within 5years of menopause. The ICEE was found to be a significant predictor of performance on the Prospective Memory task (F(1)=4.21, p=.046, η(p)(2)=.084). No significant relationship was noted between the ICEE and performance on measures of retrospective memory. The results suggest that the level of cumulative lifetime exposure to estrogen a woman has influences her prospective memory performance later in life and that the influence of reproductive and biological markers of endogenous estrogen exposure are relevant factors to consider when studying the effect of estrogen therapy on cognitive functioning in postmenopausal women. In addition, the finding that performance on a measure of prospective memory, but not performance on measures of retrospective memory, was associated with the ICEE adds further support to the theory that the frontal cortex may be especially sensitive to estrogen.     

Anterior cingulate cortex activation is related to learning potential on the WCST in schizophrenia patients

The remediation of executive function in patients with schizophrenia is important in rehabilitation because these skills affect the patient's capacity to function in the community. There is evidence that instructional techniques can improve deficits in the Wisconsin Card Sorting Test (WCST) in some schizophrenia patients. We used a standard test/training phase/standard test format of the WCST to classify 36 schizophrenia patients as high-achievers, learners or non-retainers. All healthy controls performed as high-achievers. An event-related fMRI design assessed neural activation patterns during post-training WCST performance. Patients showed a linear trend between set-shifting related activation in the anterior cingulate cortex and learning potential, i.e. increased activation in high-achievers, a trend for increased activation in learners, and no activation in non-retainers compared to controls. In addition, activation in the temporoparietal cortex was highest in patients classified as learners, whereas in non-retainers activation was increased in the inferior frontal gyrus compared to controls and high-achieving patients. These results emphasize the relevance of the ACC's neural integrity in learning set-shifting strategies for patients with schizophrenia. Also, our results support the hypothesis that compensatory neural activation in patients with schizophrenia helps them to catch up with healthy controls on cognitive tasks.     

Brain activation during spatial updating and attentive tracking of moving targets

Keeping aware of the locations of objects while one is moving requires the updating of spatial representations. As long as the objects are visible, attentional tracking is sufficient, but knowing where objects out of view went in relation to one's own body involves an updating of spatial working memory. Here, multiple object tracking was employed to study spatial updating and its neural correlates. In a dynamic 3D-scene, targets moved among visually indistinguishable distractors. The targets and distractors either stayed visible during continuous viewpoint changes or they turned invisible. The parametric variation of tracking load revealed load-dependent activations of the intraparietal sulcus, the superior parietal lobule, and the lateral occipital cortex in response to the attentive tracking task. Viewpoint changes with invisible objects that demanded retention and updating produced load-dependent activation only in the precuneus in line with its presumed involvement in updating spatial working memory.     

Feature-based versus category-based induction with uncertain categories

Previous research has suggested that when feature inferences have to be made about an instance whose category membership is uncertain, feature-based inductive reasoning is used to the exclusion of category-based induction. These results contrast with the observation that people can and do use category-based induction when category membership is known. The present experiments examined the conditions that drive feature-based and category-based strategies in induction under category uncertainty. Specifically, 2 experiments investigated whether reliance on feature-based inductive strategies is a product of the lack of coherence in the categories used in previous research or is due to the use of a decision-only induction procedure. Experiment 1 found that feature-based reasoning remained the preferred strategy even when categories with relatively high internal coherence were used. Experiment 2 found a shift toward category-based reasoning when participants were trained to classify category members prior to feature induction. Together, these results suggest that an appropriate conceptual representation must be formed through experience with a category before it is likely to be used as a basis for feature induction.