Directed forgetting in working memory: age-related differences

This study explored the effects of ageing on working memory by means of the directed forgetting procedure designed by Reed (1970). Memory for a letter trigram was compared in conditions where it was either presented alone (single-item), or followed by a second trigram to be recalled (interference), or followed by a second trigram to be forgotten (directed forgetting). The results clearly indicated that elderly participants inhibited the no-longer-relevant information less efficiently (recall in the single-item condition - recall in the directed forgetting condition), as predicted by the model of Hasher and Zacks (1988). However, the results also demonstrated that sensitivity to interference (recall in the single-item condition - recall in the interference condition) increased in the condition in which no inhibition was directly required.     

Visual skills in airport-security screening

Abstract— An experiment examined visual performance in a simulated luggage-screening task. Observers participated in five sessions of a task requiring them to search for knives hidden in x-ray images of cluttered bags. Sensitivity and response times improved reliably as a result of practice. Eye movement data revealed that sensitivity increases were produced entirely by changes in observers' ability to recognize target objects, and not by changes in the effectiveness of visual scanning. Moreover, recognition skills were in part stimulus-specific, such that performance was degraded by the introduction of unfamiliar target objects. Implications for screener training are discussed.     

Receptive fields for flexible face categorizations

Abstract-Examining the receptive fields of brain signals can elucidate how information impinging on the former modulates the latter. We applied this time-honored approach in early vision to the higher-level brain processes underlying face categorizations. Electroencephalograms in response to face-information samples were recorded while observers resolved two different categorizations (gender, expressive or not). Using a method with low bias and low variance, we compared, in a common space of information states, the information determining behavior (accuracy and reaction time) with the information that modulates emergent brain signals associated with early face encoding and later category decision. Our results provide a time line for face processing in which selective attention to diagnostic information for categorizing stimuli (the eyes and their second-order relationships in gender categorization; the mouth in expressive-or-not categorization) correlates with late electrophysiological (P300) activity, whereas early face-sensitive occipito-temporal (N170) activity is mainly driven by the contralateral eye, irrespective of the categorization task.     

Are dietary restraint scales valid measures of acute dietary restriction? Unobtrusive observational data suggest not

The finding that dietary restraint scales predict onset of bulimic pathology has been interpreted as suggesting that dieting causes this eating disturbance, despite the dearth of evidence that these scales are valid measures of dietary restriction. The authors conducted 4 studies that tested whether dietary restraint scales were inversely correlated with unobtrusively measured caloric intake. These studies, which varied in foods consumed, settings, and populations, indicated that common dietary restraint scales were largely uncorrelated with acute caloric intake. Results suggest that these scales are not valid measures of short-term dietary restriction and imply that it may be prudent to reinterpret findings from studies thai use these scales, including those that suggest dietary restraint is a risk factor for bulimic pathology.     

Regulatory and ethical principles in research involving children and individuals with developmental disabilities

Children and individuals with developmental disabilities (DD) compared to typical participants are disadvantaged not only by virtue of being vulnerable to risks inherent in research participation but also by the higher likelihood of exclusion from research altogether. Current regulatory and ethical guidelines although necessary for their protection do not sufficiently ensure fair distributive justice. Yet, in view of disproportionately higher burdens of co-occurring physical and mental disorders in individuals with DD, they are better positioned to benefit from research by equitable participation. Greater elucidation of this ethical dilemma is called for by researchers, institutional review boards, and funding agencies to urgently redress the imbalance. This article discusses many of the regulatory principles to ensure better research participation of children and individuals with DD: human rights, validity, distributive justice, beneficence/nonmaleficence, and autonomy.     

Children's competence for assent and consent: a review of empirical findings

This narrative review summarizes the empirical literature on children's competence for consent and assent in research and treatment settings. Studies varied widely regarding methodology, particularly in the areas of participant sampling, situational context studied (e.g., psychological versus medical settings), procedures used (e.g., lab-based vs. real-world approaches), and measurement of competence. This review also identifies several fundamental dilemmas underlying approaches to children's informed consent. These dilemmas, including autonomy versus best interest approaches, legal versus psychological or ethical approaches, child- versus family-based approaches, and approaches that emphasize consent versus those that emphasize assent, have implications for the measurement of children's competence and interpretation of findings. Recommendations for future research in the area of children's informed consent include the use of diverse samples and control groups, development of multidimensional and standardized measures of competence, utilization of multidimensional and standardized measures of competence, utilization of observational methods and longitudinal designs, examination of noncognitive aspects of children's competence and comparison of children's competence for treatment and research decisions.     

Postextinction infusion of a mitogen-activated protein kinase inhibitor into the medial prefrontal cortex impairs memory of the extinction of conditioned fear

We investigated whether postextinction training infusion of PD098059, a selective inhibitor of mitogen-activated protein kinase (MAPK) activation, into the medial prefrontal cortex, would impair retention of extinction learning in rats. We found that immediate, but not late (2 or 4 h), postextinction infusion of PD098059 provoked a full return of conditioned freezing. These results suggest that activation of prefrontal MAPK in early stages of postextinction training participates in processes that protect against spontaneous recovery of aversive responses.     

Sensorimotor simulations underlie conceptual representations: Modality-specific effects of prior activation

According to the perceptual symbols theory (Barsalou, 1999), sensorimotor simulations underlie the representation of concepts. Simulations are componential in the sense that they vary with the context in which the concept is presented. In the present study, we investigated whether representations are affected by recent experiences with a concept. Concept names (e.g., APPLE) were presented twice in a property verification task with a different property on each occasion. The two properties were either from the same perceptual modality (e.g.,green, shiny) or from different modalities (e.g.,tart, shiny). All stimuli were words. There was a lag of several intervening trials between the first and second presentation. Verification times and error rates for the second presentation of the concept were higher if the properties were from different modalities than if they were from the same modality.     

Brain development in autism: early overgrowth followed by premature arrest of growth

Due to the relatively late age of clinical diagnosis of autism, the early brain pathology of children with autism has remained largely unstudied. The increased use of retrospective measures such as head circumference, along with a surge of MRI studies of toddlers with autism, have opened a whole new area of research and discovery. Recent studies have now shown that abnormal brain overgrowth occurs during the first 2 years of life in children with autism. By 2-4 years of age, the most deviant overgrowth is in cerebral, cerebellar, and limbic structures that underlie higher-order cognitive, social, emotional, and language functions. Excessive growth is followed by abnormally slow or arrested growth. Deviant brain growth in autism occurs at the very time when the formation of cerebral circuitry is at its most exuberant and vulnerable stage, and it may signal disruption of this process of circuit formation. The resulting aberrant connectivity and dysfunction may lead to the development of autistic behaviors. To discover the causes, neural substrates, early-warning signs and effective treatments of autism, future research should focus on elucidating the neurobiological defects that underlie brain growth abnormalities in autism that appear during these critical first years of life.