Memoria y adquisición del conocimiento

RESUMEN

En este artículo se sitúan los trabajos clásicos de Craik y Lockhart y Craik y Tulving en el contexto del estudio global de la memoria. Se destaca el énfasis de los dos últimos en los procesos en detrimento de las descripciones estructurales, situando la clave en el nivel de profundidad al que se procese la información y subrayando la importancia de relacionarla con nuestro conocimiento del mundo. Con relación al estudio de Craik y Tulving se examinan tres cuestiones fundamentales: el procedimiento de aprendizaje incidental, el concepto de profundidad de procesamiento y la noción de memoria episódica. Para ello revisan algunos estudios que cuestionan que el procesamiento tenga lugar únicamente de abajo a arriba a través de una jerarquía de estadios fijos -según propusieron Craik y Lockhart-, abordando diversos intentos de especificar el concepto de nivel de profundidad. La última parte se reserva al problema de identificar la noción de significado psicológico con la noción de significado procedente de la Lingüística, presentando las aportaciones de los teóricos “neogibsonianos”. El trabajo finaliza con algunas reflexiones respecto al concepto de memoria episódica aportado por Tulving.     

Experimental evidence of relaxation arising from the motion of geometrical kinks on screw dislocations in iron

Abstract

Internal friction measurements with a superimposed bias stress have provided evidence for geometrical kink migration on screw dislocations in iron. This intrinsic process causes a relaxation phenomenon in internal friction which has been identified with the occurrence of a subpeak (below 20 K) of the α-peak. The effect of different bias stress has allowed us to evaluate the kink migration energy, E ^m _k ? 0·001eV.     

Processing of “unattended” threat-related information: Role of emotional content and context

Unpleasant, pleasant, or neutral visual scenes served as a context for the presentation of threat-related, positive, and neutral words. On each trial, 2 simultaneous prime words (one foveal, i.e., at fixation, and one parafoveal, i.e., 2.2° apart) appeared for 150 ms, followed by a foveally presented probe word in a lexical decision task. Results showed facilitation in response times for probe threat words when primed by an identical parafoveal word, in comparison with priming by an unrelated parafoveal word, and this effect was enhanced in an emotionally congruent unpleasant context. In contrast, no parafoveal effect appeared for positive words, even in a pleasant context. This reveals parallel processing of threat-related words outside the focus of attention.     

Overt head movements moderate the effect of depressive symptoms on mood regulation

A dysfunction in the regulation of negative mood states is one of the core symptoms of depression. Research has found that levels of depression are associated with the intensity of the mood-regulation deficit. The present study aimed to explore the role the body plays in mood-regulation processes. More specifically, we studied whether head movements can influence mood persistence in dysphoric states. Subsequent to a sad-mood induction, participants were presented with a set of positive pictures immediately after performing either vertical (i.e., nodding) or lateral (i.e., shaking) head movements. We considered changes in mood from before to after the experimental task as an index of the effectiveness of mood regulation. As expected, the results showed that higher initial levels of depressive symptoms were associated with greater persistence of sad mood. More importantly, this association was present in participants who shook their heads, but not in those who nodded. These results show that body movements can contribute to mood-regulation processes, thus expanding our knowledge of the psychopathology of mood disorders.     

Functional and connectivity changes during working memory in Huntington’s disease: 18 month longitudinal data from the IMAGE-HD study

Background

This study aimed to characterize, for the first time, 18 month longitudinal changes in both functional activation and functional connectivity during working memory in premanifest Huntington’s disease (pre-HD) and symptomatic HD (symp-HD).

Methods

Functional magnetic resonance imaging (fMRI) was used to investigate longitudinal changes in neuronal activity during working memory performance via an N-BACK task (0-BACK and 1-BACK) in 27 pre-HD, 17 symp-HD, and 23 control participants. Whole-brain analysis of activation and region-of-interest analysis of functional connectivity was applied to longitudinal fMRI data collected at baseline and 18 months follow-up.

Results

Compared with controls, the pre-HD group showed significantly increased activation longitudinally during 1-BACK versus 0-BACK in the lateral and medial prefrontal, anterior cingulate, primary motor, and temporal areas cortically, and caudate and putamen subcortically. Pre-HD far from onset, compared with controls, showed further longitudinal increases in the right and left dorsolateral prefrontal cortex (DLPFC). Longitudinal increased activation in anterior cingulate and medial primary motor areas were associated with disease burden in the pre-HD group. Moreover, in pre-HD increased activation over time in primary motor and putamen regions were associated with average response time during 1-BACK performance. During 1-BACK, functional connectivity between the right DLPFC and posterior parietal, anterior cingulate, and caudate was significantly reduced over 18 months only in the pre-HD group.

Conclusions

Longitudinal reductions in connectivity over 18 months may represent an early signature of cortico-cortical and cortico-striatal functional disconnectivity in pre-HD, whereas the concomitant increased cortical and subcortical activation may reflect a compensatory response to the demands for cognitive resources required during task performance. Our findings demonstrate that functional imaging modalities have the potential to serve as sensitive methods for the assessment of cortical and subcortical responses to future treatment measures.     

Ethics and Culture in Mental Health Care

This article examines the complex relationship between culture, values, and ethics in mental health care. Cultural competence is a practical, concrete demonstration of the ethical principles of respect for persons, beneficence (doing good), nonmaleficence (not doing harm), and justice (treating people fairly)—the cornerstones of modern ethical codes for the health professions. Five clinical cases are presented to illustrate the range of ethical issues faced by mental health clinicians working in a multicultural environment, including issues of therapeutic boundaries, diagnosis, treatment choice, confidentiality and informed consent, and the just distribution of limited health care resources.     

Implementing flexibility in automaticity: Evidence from context-specific implicit sequence learning

Attention is often dichotomized into controlled vs. automatic processing, where controlled processing is slow, flexible, and intentional, and automatic processing is fast, inflexible, and unintentional. In contrast to this strict dichotomy, there is mounting evidence for context-specific processes that are engaged rapidly yet are also flexible. In the present study we extend this idea to the domain of implicit learning to examine whether flexibility in automatic processes can be implemented through the reliance on contextual features. Across three experiments we show that participants can learn implicitly two complementary sequences that are associated with distinct contexts, and that transfer of learning when the two contexts are randomly intermixed depends on the distinctiveness of the two contexts. Our results point to the role of context-specific processes in the acquisition and expression of implicit sequence knowledge, and also suggest that episodic details can be represented in sequence knowledge.     

BRIEF REPORT: LATENCY FUNCTIONAL ANALYSIS OF ELOPEMENT

Elopement is a potentially dangerous problem behavior prevalent among individuals with developmental disabilities. However, functional analysis of elopement presents unique challenges including potential confounds because of the need for participant retrieval during functional analysis sessions. In the current study, we implemented a latency functional analysis with an eight‐year‐old child with an intellectual disability, in which the dependent measure was latency to elopement. Following the latency functional analysis, a functional communication intervention was developed and its effectiveness in decreasing elopement was evaluated using an ABAB design. Findings suggest that a functional analysis of latency may be a suitable methodology to identify the operant function of elopement. Copyright © 2013 John Wiley & Sons, Ltd.     

A letter visual-similarity matrix for Latin-based alphabets

Indicators of letter visual similarity have been used for controlling the design of empirical and neuropsychological studies and for rigorously determining the factors that underlie reading ability and literacy acquisition. Additionally, these letter similarity/confusability matrices have been useful for studies examining more general aspects of human cognition, such as perception. Despite many letter visual-similarity matrices being available, they all have two serious limitations if they are to be used by researchers in the reading domain: (1) They have been constructed using atypical reading data obtained from speeded reading-aloud tasks and/or under degraded presentation conditions; (2) they only include letters from the English alphabet. Although some letter visual-similarity matrices have been constructed using data gathered from normal reading conditions, these either are based on old fonts, which may not resemble the letters found in modern print, or were never published. For the first time, this article presents a comprehensive letter visual-similarity/confusability matrix that has been constructed based on untimed responses to clearly presented upper- and lowercase letters that are present in many languages that use Latin-based alphabets, including Catalan, Dutch, English, French, Galician, German, Italian, Portuguese, and Spanish. Such a matrix will be useful for researchers interested in the processes underpinning reading and literacy acquisition.     

Perceptual organization and artificial attention for visual landmarks detection

In biological vision systems, attention mechanisms are responsible for selecting the relevant information from the sensed field of view, so that the complete scene can be analyzed using a sequence of rapid eye saccades. In recent years, efforts have been made to imitate such attention behavior in artificial vision systems, because it allows optimizing the computational resources as they can be focused on the processing of a set of selected regions. In the framework of mobile robotics navigation, this work proposes an artificial model where attention is deployed at the level of objects (visual landmarks) and where new processes for estimating bottom-up and top-down (target-based) saliency maps are employed. Bottom-up attention is implemented through a hierarchical process, whose final result is the perceptual grouping of the image content. The hierarchical grouping is applied using a Combinatorial Pyramid that represents each level of the hierarchy by a combinatorial map. The process takes into account both image regions (faces in the map) and edges (arcs in the map). Top-down attention searches for previously detected landmarks, enabling their re-detection when the robot presumes that it is revisiting a known location. Landmarks are described by a combinatorial submap; thus, this search is conducted through an error-tolerant submap isomorphism procedure.