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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Sequential Encoding in Visual Working Memory: In the Absence of Structure, Recency Determines Performance

Durbin, Jeffery 29 October 2019 (has links)
Most prior investigations of visual working memory (VWM) presented the to-be-remembered items simultaneously in a static configuration (e.g., Luck & Vogel, 1997). However, in everyday situations, such as driving on a busy multilane highway, items (e.g., cars) are presented sequentially and must be retained to support later actions (e.g., knowing if it’s safe to change lanes). In a simultaneous presentation, the relative positions of items are apparent but for sequential presentation, relative positions must be inferred in relation to the background structure (e.g., highway lane markings). To examine sequential encoding in VWM, we developed a novel task in which dots were presented slowly, one at a time, with each dot appearing in one of six boxes (Experiment 1), or in invisible boxes within a visible encompassing outer frame (Experiment 2). Experiment 1 found strong recency effects for judgments of color at the end of the sequence but not for the location of dots. In contrast, without dividing lines, Experiment 2 found strong recency effects for both color and location judgments. These results held true for accuracy, reaction time, and an integrated measure of speed and accuracy. We hypothesize that background structure allows the updating of VWM, slotting each new item into that structure to provide a new configuration that retains both old and new items, whereas in the absence of structure, VWM suffers from severe retroactive interference.
2

Diagnostic Feature Detection and Sequential Eyewitness Lineups

Hoover, Jerome D. 14 November 2023 (has links) (PDF)
Prior work has demonstrated that the sequential presentation of lineup members in eyewitness lineups can result in undesirable position effects. For example, some studies have shown that placing the suspect in later positions increases discriminability. However, the evidence for this late-position discriminability advantage is mixed and the processes by which the discriminability increase occurs are unclear. However, one theory in particular, diagnostic feature detection theory (DFDT) explicitly predicts a late-position discriminability increase. According to DFDT, because shared features across lineup members cannot be used as reliable recognition cues to guide identification, discounting these features from consideration improves recognition. In sequential lineups, when the suspect is in a later position, witnesses are exposed to more of these shared features and are expected to benefit from discounting. By contrast, when the suspect is in an earlier position, witnesses are exposed to fewer shared features, and hence do not have the same advantage under the assumptions of the DFDT framework. One reason for the mixed evidence across the literature might be due to variation in suspect-filler similarity relationship between lineup members across studies, which we expected would moderate late-position memory effects. With the above in mind, the primary goals of the present work were: (1) testing for position effects at different levels of suspect-filler (SF) similarity, which might help elucidate conflicting evidence from prior work, and (2) testing DFDT mechanisms by simultaneously manipulating both innocent-suspect-perpetrator (IS-P) similarity and SF similarity. We found no evidence for late-position increases in discriminability as predicted by DFDT; however, participants were more conservative in later positions, especially when SF similarity was low. Discriminability was most strongly influenced by IS-P similarity, and was maximized when both SF and IS-P similarity was low. Implications for theories of eyewitness memory, practical implications for policy recommendations, and future directions are discussed.
3

False recall serial position effects

Lane, David Guy 31 March 2011
A series of 5 experiments investigated whether false memory in associated word lists present with serial position effects (SPE) and how any such effects behave in response to manipulations of true recall SPE. Recall for a series of events is typified by SPE such that items nearer the beginning, primacy effect, and end, recency effect, of a series are remembered better than middle items. Recall is also typified by the intrusion of falsely remembered information. Word-lists segmented into trimesters of either semantically (e.g., hot, snow, warm.../ bed, rest, awake.../ looking, lens, shatter...) or phonologically (e.g., code, called, fold.../ sweep, sleet, steep.../ class, grass, glad...) associated words produced false recall (e.g., cold, sleep, glass), allowing for the simultaneous investigation of SPE for true and false recall. Typical SPE for true recall were observed for each of the five Experiments. For immediate free recall, semantic false recall declined from early to late study trimesters whereas phonological false recall displayed a false primacy and recency effect similar to true recall SPE. Phonological false recall was significantly reduced when a 15 second distractor task was implemented during the retention interval. Dividing attention during study using a concurrent handwriting task reduced true recall whereas semantic false recall increased at primacy and phonological false recall increased at recency. This suggests distinct processes underlying the two forms of false recall. Dividing attention using an articulatory suppression task produced less true recall and less false recall than using concurrent handwriting. This research indicates that false recall SPE exist and that the semantic and phonological forms of false recall SPE are distinct. Current theories of false memory and of true recall SPE are considered.
4

False recall serial position effects

Lane, David Guy 31 March 2011 (has links)
A series of 5 experiments investigated whether false memory in associated word lists present with serial position effects (SPE) and how any such effects behave in response to manipulations of true recall SPE. Recall for a series of events is typified by SPE such that items nearer the beginning, primacy effect, and end, recency effect, of a series are remembered better than middle items. Recall is also typified by the intrusion of falsely remembered information. Word-lists segmented into trimesters of either semantically (e.g., hot, snow, warm.../ bed, rest, awake.../ looking, lens, shatter...) or phonologically (e.g., code, called, fold.../ sweep, sleet, steep.../ class, grass, glad...) associated words produced false recall (e.g., cold, sleep, glass), allowing for the simultaneous investigation of SPE for true and false recall. Typical SPE for true recall were observed for each of the five Experiments. For immediate free recall, semantic false recall declined from early to late study trimesters whereas phonological false recall displayed a false primacy and recency effect similar to true recall SPE. Phonological false recall was significantly reduced when a 15 second distractor task was implemented during the retention interval. Dividing attention during study using a concurrent handwriting task reduced true recall whereas semantic false recall increased at primacy and phonological false recall increased at recency. This suggests distinct processes underlying the two forms of false recall. Dividing attention using an articulatory suppression task produced less true recall and less false recall than using concurrent handwriting. This research indicates that false recall SPE exist and that the semantic and phonological forms of false recall SPE are distinct. Current theories of false memory and of true recall SPE are considered.
5

Semantisk information i arbetsminne / Semantic Information in Working Memory

Johansson, Adam January 2018 (has links)
Mycket av vår kognitiva förmåga beror på lagringen och bearbetande av meningen olika objekt, ord eller handlingar innefattar. Denna mening kallas för semantik där semantik inom arbetsminne har till största del ignorerats och istället tillskrivits långtids semantiskt minne. Med användning Baddley och Hitch model av arbetsminne är målet av denna studie att tillskriva semantisk bearbetning till en komponent inom modellen, undersöka skillnader mellan typer av semantiskt material till episodiskt material och hur dessa är påverkade av seriella positionseffekter. Relaterad semantik, orelaterad semantik och episodiskt material var inkluderade i studien och var representerade av ord-par. 42 deltagare, med användningen av en bekvämlighetsurvalsmetod, blev slumpmässigt tilldelade ett av tre experimentella förhållanden designade för att förändra mängden material som de kan memorera. Det första experimentella förhållandet fastställde att med direkt återkallelse hade semantiskt material högre grad av återkallelse än episodiskt material. Det andra experimentella förhållandet visade att effekten av artikulatoriskt undertryckande (articulatory suppression) inte signifikant sänker mängden som memorerat. Det tredje förhållandet demonstrerade att fördröjd återkallelse signifikant förminskade mängden orelaterad semantik. Dessa resultat visade att semantiskt material återkallas till högre grad men relaterad semantik och orelaterad semantik lagras av olika system då orelaterad semantik är påverkad av förfall (decay) eller störning (interference). Resultaten visade betydelsen av att använda simpelt och precist språk för att ge ett mer effektivt sätt att memorera och lära sig. / Much of our cognitive abilities rely on maintaining and processing the meaning of different objects, words or actions. This meaning is known as semantics however, the use of semantics in working memory have been mostly ignored and instead attributed to long-term semantic memory. Using Baddeley and Hitch’s model of working memory this study aims to attribute semantic maintenance to a component within the model, examine differences between types of semantic material to episodic material and how these were affected by serial position effects. Related semantics, unrelated semantics and episodic material were included in the study which were all represented by word-pairs. 42 participants, using a convenience sampling method, were randomly assigned to one of three experimental conditions designed to alter the amount of material memorized. The first experimental condition, by using immediate recall, demonstrated that semantic materials had a significantly superior recall rate than episodic materials. The second experimental condition showed that the effect articulatory suppression didn’t significantly reduce the amount memorized. The third condition demonstrated that delayed recall significantly reduced the amount of unrelated semantics. These findings showed that semantic materials had superior recall but related and unrelated semantic material were found to be maintained by different systems as unrelated material was subject to decay or interference. The results showed the importance using simple and precise language to provide a more effective way to memorize and learn.
6

Kontexteffekte in Large-Scale Assessments

Weirich, Sebastian 13 August 2015 (has links)
Im Rahmen der Item-Response-Theorie evaluiert die kumulative Dissertationsschrift verschiedene Methoden und Modelle zur Identifikation von Kontexteffekten in Large-Scale Assessments. Solche Effekte können etwa in quantitativen empirischen Schulleistungsstudien auftreten und zu verzerrten Item- und Personenparametern führen. Um in Einzelfällen abschätzen zu können, ob Kontexteffekte auftreten und dadurch die Gefahr verzerrter Parameter gegeben ist (und falls ja, in welcher Weise), müssen IRT-Modelle entwickelt werden, die zusätzlich zu Item- und Personeneffekten Kontexteffekte parametrisieren. Solch eine Parametrisierung ist im Rahmen Generalisierter Allgemeiner Linearer Modelle möglich. In der Dissertation werden Positionseffekte als ein Beispiel für Kontexteffekte untersucht, und es werden die statistischen Eigenschaften dieses Messmodells im Rahmen einer Simulationsstudie evaluiert. Hier zeigt sich vor allem die Bedeutung des Testdesigns: Um unverfälschte Parameter zu gewinnen, ist nicht nur ein adäquates Messmodell, sondern ebenso ein adäquates, also ausbalanciertes Testdesign notwendig. Der dritte Beitrag der Dissertation befasst sich mit dem Problem fehlender Werte auf Hintergrundvariablen in Large-Scale Assessments. Als Kontexteffekt wird in diesem Beispiel derjenige Effekt verstanden, der die Wahrscheinlichkeit eines fehlenden Wertes auf einer bestimmten Variablen systematisch beeinflusst. Dabei wurde das Prinzip der multiplen Imputation auf das Problem fehlender Werte auf Hintergrundvariablen übertragen. Anders als bisher praktizierte Ansätze (Dummy-Codierung fehlender Werte) konnten so in einer Simulationsstudie für fast alle Simulationsbedingungen unverfälschte Parameter auf der Personenseite gefunden werden. / The present doctoral thesis evaluates various methods and models of the item response theory to parametrize context effects in large-scale assessments. Such effects may occur in quantitative educational assessments and may cause biased item and person parameter estimates. To decide whether context effects occur in individual cases and lead to biased parameters, specific IRT models have to be developed which parametrize context effects additionally to item and person effects. The present doctoral thesis consists of three single contributions. In the first contribution, a model for the estimation of context effects in an IRT framework is introduced. Item position effects are examined as an example of context effects in the framework of generalized linear mixed models. Using simulation studies, the statistical properties of the model are investigated, which emphasizes the relevance of an appropriate test design. A balanced incomplete test design is necessary not only to obtain valid item parameters in the Rasch model, but to guarantee for unbiased estimation of position effects in more complex IRT models. The third contribution deals with the problem of missing background data in large-scale assessments. The effect which predicts the probability of a missing value on a certain variable, is considered as a context effect. Statistical methods of multiple imputation were brought up to the problem of missing background data in large-scale assessments. In contrast to other approaches used so far in practice (dummy coding of missing values) unbiased population and subpopulation estimates were received in a simulation study for most conditions.
7

Essays zu methodischen Herausforderungen im Large-Scale Assessment

Robitzsch, Alexander 21 January 2016 (has links)
Mit der wachsenden Verbreitung empirischer Schulleistungsleistungen im Large-Scale Assessment gehen eine Reihe methodischer Herausforderungen einher. Die vorliegende Arbeit untersucht, welche Konsequenzen Modellverletzungen in eindimensionalen Item-Response-Modellen (besonders im Rasch-Modell) besitzen. Insbesondere liegt der Fokus auf vier methodischen Herausforderungen von Modellverletzungen. Erstens, implizieren Positions- und Kontexteffekte, dass gegenüber einem eindimensionalen IRT-Modell Itemschwierigkeiten nicht unabhängig von der Position im Testheft und der Zusammenstellung des Testheftes ausgeprägt sind und Schülerfähigkeiten im Verlauf eines Tests variieren können. Zweitens, verursacht die Vorlage von Items innerhalb von Testlets lokale Abhängigkeiten, wobei unklar ist, ob und wie diese in der Skalierung berücksichtigt werden sollen. Drittens, können Itemschwierigkeiten aufgrund verschiedener Lerngelegenheiten zwischen Schulklassen variieren. Viertens, sind insbesondere in low stakes Tests nicht bearbeitete Items vorzufinden. In der Arbeit wird argumentiert, dass trotz Modellverletzungen nicht zwingend von verzerrten Schätzungen von Itemschwierigkeiten, Personenfähigkeiten und Reliabilitäten ausgegangen werden muss. Außerdem wird hervorgehoben, dass man psychometrisch häufig nicht entscheiden kann und entscheiden sollte, welches IRT-Modell vorzuziehen ist. Dies trifft auch auf die Fragestellung zu, wie nicht bearbeitete Items zu bewerten sind. Ausschließlich Validitätsüberlegungen können dafür Hinweise geben. Modellverletzungen in IRT-Modellen lassen sich konzeptuell plausibel in den Ansatz des Domain Samplings (Item Sampling; Generalisierbarkeitstheorie) einordnen. In dieser Arbeit wird gezeigt, dass die statistische Unsicherheit in der Modellierung von Kompetenzen nicht nur von der Stichprobe der Personen, sondern auch von der Stichprobe der Items und der Wahl statistischer Modelle verursacht wird. / Several methodological challenges emerge in large-scale student assessment studies like PISA and TIMSS. Item response models (IRT models) are essential for scaling student abilities within these studies. This thesis investigates the consequences of several model violations in unidimensional IRT models (especially in the Rasch model). In particular, this thesis focuses on the following four methodological challenges of model violations. First, position effects and contextual effects imply (in comparison to unidimensional IRT models) that item difficulties depend on the item position in a test booklet as well as on the composition of a test booklet. Furthermore, student abilities are allowed to vary among test positions. Second, the administration of items within testlets causes local dependencies, but it is unclear whether and how these dependencies should be taken into account for the scaling of student abilities. Third, item difficulties can vary among different school classes due to different opportunities to learn. Fourth, the amount of omitted items is in general non-negligible in low stakes tests. In this thesis it is argued that estimates of item difficulties, student abilities and reliabilities can be unbiased despite model violations. Furthermore, it is argued that the choice of an IRT model cannot and should not be made (solely) from a psychometric perspective. This also holds true for the problem of how to score omitted items. Only validity considerations provide reasons for choosing an adequate scoring procedure. Model violations in IRT models can be conceptually classified within the approach of domain sampling (item sampling; generalizability theory). In this approach, the existence of latent variables need not be posed. It is argued that statistical uncertainty in modelling competencies does not only depend on the sampling of persons, but also on the sampling of items and on the choice of statistical models.
8

Optimierung von Messinstrumenten im Large-scale Assessment

Hecht, Martin 21 July 2015 (has links)
Messinstrumente stellen in der wissenschaftlichen Forschung ein wesentliches Element zur Erkenntnisgewinnung dar. Das Besondere an Messinstrumenten im Large-scale Assessment in der Bildungsforschung ist, dass diese normalerweise für jede Studie neu konstruiert werden und dass die Testteilnehmer verschiedene Versionen des Tests bekommen. Hierbei ergeben sich potentielle Gefahren für die Akkuratheit und Validität der Messung. Um solche Gefahren zu minimieren, sollten (a) die Ursachen für Verzerrungen der Messung und (b) mögliche Strategien zur Optimierung der Messinstrumente eruiert werden. Deshalb wird in der vorliegenden Dissertation spezifischen Fragestellungen im Rahmen dieser beiden Forschungsanliegen nachgegangen. / Measurement instruments are essential elements in the acquisition of knowledge in scientific research. Special features of measurement instruments in large-scale assessments of student achievement are their frequent reconstruction and the usage of different test versions. Here, threats for the accuracy and validity of the measurement may emerge. To minimize such threats, (a) sources for potential bias of measurement and (b) strategies to optimize measuring instruments should be explored. Therefore, the present dissertation investigates several specific topics within these two research areas.

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