Effect of non-normality on test statistics for one-way independent groups designs

The data obtained from one‐way independent groups designs is typically non‐normal in form and rarely equally variable across treatment populations (i.e. population variances are heterogeneous). Consequently, the classical test statistic that is used to assess statistical significance (i.e. the analysis of variance F test) typically provides invalid results (e.g. too many Type I errors, reduced power). For this reason, there has been considerable interest in finding a test statistic that is appropriate under conditions of non‐normality and variance heterogeneity. Previously recommended procedures for analysing such data include the James test, the Welch test applied either to the usual least squares estimators of central tendency and variability, or the Welch test with robust estimators (i.e. trimmed means and Winsorized variances). A new statistic proposed by Krishnamoorthy, Lu, and Mathew, intended to deal with heterogeneous variances, though not non‐normality, uses a parametric bootstrap procedure. In their investigation of the parametric bootstrap test, the authors examined its operating characteristics under limited conditions and did not compare it to the Welch test based on robust estimators. Thus, we investigated how the parametric bootstrap procedure and a modified parametric bootstrap procedure based on trimmed means perform relative to previously recommended procedures when data are non‐normal and heterogeneous. The results indicated that the tests based on trimmed means offer the best Type I error control and power when variances are unequal and at least some of the distribution shapes are non‐normal.     

Neurogenesis interferes with the retrieval of remote memories: Forgetting in neurocomputational terms

In contrast to models and theories that relate adult neurogenesis with the processes of learning and memory, almost no solid hypotheses have been formulated that involve a possible neurocomputational influence of adult neurogenesis on forgetting. Based on data from a previous study that implemented a simple but complete model of the main hippocampal circuitry (Weisz & Argibay, 2009), we now test this model under different situations to better study the case of remote memories. The results of this work show that following neurogenesis, the new, ongoing memories in the hippocampus are better retained than when no neurogenesis occurs at all, while the older memories are affected (to a lesser extent) by a special type of interference that is different from interference that occurs with an increasing number of memories per se. This work adds a new point of analysis in support of the interference view that might lead to the forgetting of memories in the hippocampus as they are transferred to neocortex for long-term storage, consistent with the Complementary Learning Systems models of system-level consolidation. Attention should be directed to the specific causes of interference; the results of this work signal a type of distortion of remote memories that is produced by the birth and the growth of new processing units, which results in a subtly impoverished retrieval as new neurons become active. The proposals of this model fit well with some empirical findings that are related to the issue. In the future, as new evidence emerges, we believe that this biological process, which is largely related to learning and memory, will also help to shape our ideas about normal forgetting and its possible contributions to system consolidation.     

Control networks and neuromodulators of early development

In adults, most cognitive and emotional self-regulation is carried out by a network of brain regions, including the anterior cingulate, insula, and areas of the basal ganglia, related to executive attention. We propose that during infancy, control systems depend primarily upon a brain network involved in orienting to sensory events that includes areas of the parietal lobe and frontal eye fields. Studies of human adults and alert monkeys have shown that the brain network involved in orienting to sensory events is moderated primarily by the nicotinic cholinergic system arising in the nucleus basalis. The executive attention network is primarily moderated by dopaminergic input from the ventral tegmental area. A change from cholinergic to dopaminergic modulation would be a consequence of this switch of control networks and may be important in understanding early development. We trace the attentional, emotional, and behavioral changes in early development related to this developmental change in regulative networks and their modulators.     

Individual differences in adolescents' sympathetic and parasympathetic functioning moderate associations between family environment and psychosocial adjustment

The present study tested whether individual differences in autonomic nervous system functioning interact with environmental risk factors to predict adolescents' psychosocial functioning. The authors assessed skin conductance and respiratory sinus arrhythmia at rest and during laboratory stressors in 110 14-year-olds. Subsequently, adolescents and their mothers provided both questionnaire and daily diary data (over 10 days) on emotional and interpersonal functioning. The authors found stronger associations between environmental risk factors (having a single-mother household or a mother with high internalizing problems) and psychosocial outcomes (externalizing problems, daily negative affect, and daily interaction quality) among youths with specific patterns of tonic and stress-induced sympathetic and parasympathetic nervous system activity, but the pattern of moderating effects differed between boys and girls. The findings support the notion that individual differences in autonomic functioning index variation in youth's susceptibility to environmental risk factors.     

Retrieval-induced forgetting of arithmetic facts

Retrieval-induced forgetting (RIF) is a widely studied phenomenon of human memory, but RIF of arithmetic facts remains relatively unexplored. In 2 experiments, we investigated RIF of simple addition facts (2 + 3 = 5) from practice of their multiplication counterparts (2 × 3 = 6). In both experiments, robust RIF expressed in response times occurred only for high-strength small-number addition facts with sums ≤ 10, indicating that RIF from multiplication practice was interference dependent. RIF of addition-fact memory was produced by multiplication retrieval (2 × 3 = ?) but not multiplication study (2 × 3 = 6), supporting an inhibitory mechanism of RIF in arithmetic memory. Finally, RIF occurred with multiplication practiced in word format (three × four) and addition tested later in digit format (3 + 4), which provides evidence that digit and written-word formats for arithmetic accessed a common semantic retrieval network. The results support the view that addition and multiplication facts are stored in an interrelated semantic network and that RIF of competing addition facts is an intrinsic process of multiplication fact retrieval.     

The influence of response conflict on voluntary task switching: a novel test of the conflict monitoring model

The conflict monitoring model of cognitive control posits that response conflict triggers a top-down enhancement of a task’s representation in working memory. In the present study, we conducted a novel test of the conflict monitoring model using a voluntary task switching paradigm. We predicted that a task’s representation would be enhanced following events associated with high response conflict (i.e., incongruent trials and incorrect responses), leading participants to voluntarily choose to repeat that task more often after these events than after events associated with low response conflict (i.e., congruent trials and correct responses). In two experiments, performance following incongruent trials was consistent with the conflict monitoring model. However, performance following incorrect trials did not fit with the model’s predictions. These findings provide novel support for the conflict monitoring model while revealing new effects of incorrect trials that the model cannot explain.     

Grouping by achromatic color and surface segregation

The study explored the achromatic-color determinants of grouping of uniform surfaces. The stimuli were a set of separate uniform achromatic disks on either a uniform or a bipartite achromatic background. The participants rated the salience of grouping of these disks for different combinations of stimulus luminances. The results show that achromatic color similarity alone could not sufficiently explain the pattern of obtained factorial curves but this factor coupled with the factor of surface segregation could. Luminance contrast similarity per se was found to be unimportant for grouping.     

Multiple trials may yield exaggerated effect size estimates

Published psychological research attempting to support the existence of small and medium effect sizes may not have enough participants to do so accurately, and thus, repeated trials or the use of multiple items may be used in an attempt to obtain significance. Through a series of Monte-Carlo simulations, this article describes the results of multiple trials or items on effect size estimates when the averages and aggregates of a dependent measure are analyzed. The simulations revealed a large increase in observed effect size estimates when the numbers of trials or items in an experiment were increased. Overestimation effects are mitigated by correlations between trials or items, but remain substantial in some cases. Some concepts, such as a P300 wave or a test score, are best defined as a composite of measures. Troubles may arise in more exploratory research where the interrelations among trials or items may not be well described.     

Errors in identifying and expressing emotion in facial expressions, voices, and postures unique to social anxiety

The purpose of the present study was to see if 7-10-year-old socially anxious children (n = 26) made systematic errors in identifying and sending emotions in facial expressions, paralanguage, and postures as compared with the more random errors of children who were inattentive-hyperactive (n = 21). It was found that socially anxious children made more errors in identifying anger and fear in children's facial expressions and anger in adults' postures and in expressing anger in their own facial expressions than did their inattentive-hyperactive peers. Results suggest that there may be systematic difficulties specifically in visual nonverbal emotion communication that contribute to the personal and social difficulties socially anxious children experience.     

Judaism and Health: Reflections on an Emerging Scholarly Field

This paper surveys the field of Judaism and health. The authors trace the history of discourse on health and healing within Judaism, from the biblical and rabbinic eras to contemporary research and writing on Jewish bioethics, pastoral care, communal services, and aging, including congregational and community programming related to health and illness and the emergence of the Jewish healing movement. The work of the Kalsman Institute on Judaism and Health is described, focusing on efforts to unite these various threads into a scholarly field emphasizing basic and applied research on the instrumental functions of Jewish religious life for health and well-being.