1,720,954 research outputs found
Can people drop objects from their working memory
No full textStudien zeigen, dass ein durchschnittlicher, gesunder Mensch drei bis vier Objekte im visuellen Arbeitsgedächtnis (vA) halten kann. Ikkai, McCollough und Vogel [1] zeigen außerdem, dass es in einem lateralisierten change-detection-vA-Task möglich ist, im EEG-Signal eine negative Ablenkung über dem Parietallappen zu beobachten. Diese ist auf jener Seite stärker ausgeprägt, die sich kontralateral zum Halbfeld befindet, in dem die zu merkenden Objekte gezeigt werden. Der Unterschied zwischen den Amplituden, die über der kontralateralen und der ipsilateralen Gehirnhälfte gemessen werden, wird Contrala-teral Delay Activity (CDA) genannt. Es wird angenommen, dass CDA die aktuelle Auslastung des Arbeitsgedächtnises widerspiegelt. Weitere Experimente haben gezeigt, dass die Ausprägung der CDA eng verbunden ist mit der individuellen Kapazität des vA. [2] Da CDA die Auslastung des vA wiedergibt, wurde es erfolgreich eingesetzt um die Fähigkeit zu untersuchen, irrelevante Informationen aus dem vA zu filtern. [3] In Hinblick auf die Beobachtung dieses aktiven Filterns von Elementen aus dem vA, zielt die hier vorliegende Studie darauf ab festzustellen, ob es Menschen möglich ist, auch während des Aufrechterhaltens des vA Informationen zu löschen.
Methoden
25 gesunde, junge Erwachsene nahmen an der Studie teil. Jeder Teilnehmende durchlief 288 Trials eines Change-Detection-Tasks. Die Teilnehmenden wurden instruiert sich entweder zwei oder vier Objekte zu merken und später entweder keines oder zwei dieser Objekte aus dem vA zu löschen. 32 Kanäle wurden verwendet um während des Experi-ments ereigniskorrelierte Potentiale (EKP) aufzuzeichnen.
Ergebnisse
In Übereinstimmung mit früheren Studien, erwarteten wir eine positive Korrelation von Aufnahmefähigkeit des vA und dem Vermögen Objekte aus dem Arbeitsgedächtnis zu lö-schen. Behaviorale Daten bestätigen die Hypothese im Falle von vier Objekten, jedoch nicht im Falle von zwei Objekten. Dies zeigt möglicherweise, wie einfach der Task im Falle von nur zwei Elementen durchgeführt werden konnte. Die weitere Analyse der behavioralen Daten hat allerdings dazu geführt, die Hypothese zurückzuweisen, dass Menschen Objekte aus dem Arbeitsgedächtnis löschen können.
Das relativ schlechte Signal-Rausch-Verhältnis in den EKP Daten hat zu einigen Schwierigkeiten in der Analyse geführt. Um ein besseres Verhältnis zu bekommen, sollte das Experiment mit einigen Verbesserungen noch einmal durchgeführt werden.The studies show that a healthy young adult can successfully maintain 3-4 objects in Visual working memory (Visual WM) in average. Ikkai, McCollough and Vogel [1] have further shown that in a lateralized change detection Visual WM task, it is possible to observe a negative deflection in EEG over parietal cortex, which is stronger on the side contralateral to the hemifield in which items to be remembered were shown. The difference between the amplitude measured over ipsilateral and contralateral hemisphere—termed Contralateral Delay Activity (CDA)—is assumed to reflect the current working memory load. Further experiments have shown that the magnitude of CDA is closely related to individual's Visual WM capacity. [2] As it tracks Visual WM load, it has been successfully used to study the ability to filter unrelated information from Visual WM. [3] Analogue to observing active filtering of items from Visual WM, the current study aims to investigate, whether people can drop objects from Visual WM during the maintenance period.
Methods
25 healthy young adults participated in the study. Each participant performed 288 trials of a change detection task. Participants were instructed to memorize 2 or 4 objects and later either keep all of the objects in their Visual WM or drop half of them. Event-related potentials from 32 channel locations were recorded during the performance of the task.
Results & Discussion
Similar to the earlier studies, we expected to find a positive correlation between Visual WM capacity and the ability to drop objects from working memory. Behavioral data confirmed the correlation at the load of 4, but not at the load of 2 items, possibly reflecting the ease of performing the task at the Visual WM load of 2 items. However, the further analysis of behavioral data resulted in the rejection of the hypothesis that people can drop objects from their WM.
ERP data were too noisy and this led to some difficulties in interpreting ERP analysis. The experiment should be repeated with some improvements to obtain clearer ERP data
Parametric Working Memory of Abstract Quantities on Multiple Modalities and Formats : from Frequency to Numerosity
Get PDFWorking memory is central to the complex cognitive functions that are involved in goal-directed behavior. At the core of working memory research, the question remains how and in what format information is retained in the brain. Immense progress has been made using neuroimaging to determine the location of information maintenance using experiments with sensory features, however, it remains unclear how more abstract stimuli are stored.
The aim of this dissertation is to uncover the neural underpinnings of working memory during abstract quantity processing. Specifically, I conducted three functional magnetic resonance imaging (fMRI) studies to address the question of which brain regions represent the abstract quantity content. We found parametric working memory representation of auditory, visual and vibrotactile frequencies distributed across sensory, posterior parietal, and prefrontal cortices. Additionally, the numerosity-specific information is represented in the prefrontal cortex.
These results provide novel insights into how the brain maintains information in working memory and give support to the view that mental representations are distributed across the cortex depending on whether they are maintained as sensory-specific or abstract features
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
