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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

Electrophysiological correlates of complex attentional selection

Schöne, Benjamin 08 May 2018 (has links)
Attention is one of the pivotal research subjects in psychological science. Its major function is to select relevant information from the sensory streams and suppress distracting information. As the capacity of the brain is limited, a task-oriented selection of input is a crucial feature of cognition, promoting efficient behavior. Early approaches of attentional systems thus focused on this to a high degree passive perceptual filtering aspect of attention. Most influential is for example Broadbent's model (1958), assuming that relevant information is filtered out during early stages of the sensory stream, while ignored information is completely lost. This theory was quickly complemented by Deutsch and Deutsch (1963) with a mechanism for late selection, showing that information can be semantically processed without awareness and later selected according to situational demands. As a hybrid model of early and late selection, Lavie's load theory (1994) addressed two main questions arising from the initial approaches: At which stage of the sensory stream does selection occur and to which extent is ignored information processed. Lavie concluded that under high information load, irrelevant information is suppressed at early stages, whereas under low load, when the brain's capacity is not exhausted, it is processed in depth. Although widely accepted and believed to correspond to the functional properties of cognitive processes, even load-dependent theories do not account for all kinds of attentional phenomena. Especially the complex interactions of affect, memory as well as executive functions, which constitute the variety of attentional processes, make it difficult to develop an integrative framework of attention. This is particularly the case, since conventional approaches to attention still seem to be under the intermediate immersion of the attention solely as a perceptual filter. Inspired by more holistic and integrative approaches by Nelson Cowan and Eric Kandel, who regard attention as a constructive, even creative process this dissertation aims to illuminate the phenomenon of attention from several perspectives. The purpose is to gain insights, which go beyond the results obtained by conventional or so to say conservative 6 paradigms. Four electrophysiological studies are applied to investigate attentional mechanisms and structure along the visual information stream. Study 1 investigates the electrophysiological correlates (ERPs) of automatic allocation gain, reflected by the P1 component, in response to highly salient stimuli, making a case for motivational relevance in attentional processing. Study 2 takes a closer look at said gain processes, investigating frontal alpha asymmetries, which index modulation of striatal reward encoding. Further top-down modulations are the research subject of Study 3, which puts declarative memory into focus. Specifically, the effects of functional network properties of long-term memory encoding self-relevant information on attentional gain mechanism are investigated. As a result, self-referential processing is based on automatic retrieval of personal information as opposed to the processing of unknown persons, which requires voluntary, that is, strategic, attention-demanding processing as indexed by the N170 and the N400 component, respectively. Study 4 investigated the neural efficiency gains related to meditation practice combining multiple object tracking with steady-state visually evoked potentials. The results shed new light on the interaction of attentional focus and visual short- term memory, showing that enhanced distractor resistance profits from attentional de- automatization, thereby increasing capacity limits of visual short-term memory. In the general discussion of this thesis, Cowan's integrated framework of attention provides a reference for evaluating and relating the results in s structured manner in order to overcome the limitations of the perceptual filter approach. An updated version of Cowan’s framework is furthermore proposed, incorporating the new empirical data. Last but not least, new questions, concepts and predictions arising from the model are discussed.
2

Denken mit und über Kausalmodelle / Reasoning by vs. Reasoning about Causal Models

Hagmayer, York Christoph 01 February 2001 (has links)
No description available.
3

Körperliche Reinigung und psychische Funktionen

Kaspar, Kai 23 December 2015 (has links)
Psychische Ursachen und Effekte körperlicher Reinigung waren lange Zeit nur ein Randthema psychologischer Forschung. Inspiriert durch die in vielen Religionen und Medien häufig thematisierte metaphorische Verbindung zwischen körperlicher und moralischer Reinheit konnte in den letzten Jahren substantielle empirisch Evidenz für einen tatsächlichen psychologischen Mechanismus gefunden werden. Dabei zeigte sich auch, dass körperliche Reinigung über die Domäne moralischer Selbstbilder und Urteile hinaus bedeutsame Effekte auf psychische Funktionen haben kann. Die vorliegende Arbeit stellt die Entwicklung und den aktuellen Stand dieser Forschungslinie dar. Insbesondere beinhaltet sie fünf empirische Studien, die verschiedene Facetten körperlicher Reinheit mit Blick auf psychische Funktionen untersuchen. In Studie 1 wird erstmalig demonstriert, dass Händewaschen nach einem Misserfolgserlebnis in einer kognitiven Problemlöseaufgabe den Optimismus, zukünftig eine bessere Leistung zeigen zu können, signifikant steigerte, dabei jedoch die tatsächliche spätere Leistung reduzierte. In Studie 2 wird vor dem Hintergrund unterschiedlicher theoretischer Annahmen über die Wirkung von körperlicher Reinigung gezeigt, dass Händewaschen die Tendenz verstärkter stereotyper moralischer Urteile abschwächt und gleichzeitig die Herunterregulierung physiologischer Erregung begünstigt. Dabei wird erstmalig eine Blickbewegungs- und Pupillometrie-Messung im Forschungsfeld durchgeführt, um objektive Indikatoren für Informationsaufnahmeprozesse und physiologische Erregung zu nutzen. In Studie 3 wird demonstriert, wie ausgehend von der Annahme einer modulierten Gewichtung kognitiver Information durch Händewaschen dieses die Gedächtnisleistung für moralische und unmoralische Inhalte zugunsten letzterer verändert. Studie 4 untersucht, wie die aktive Reinigung der Hände sowie die bloße Aktivierung von Reinheitskognitionen die eingeschätzte Wahrscheinlichkeit für zukünftige moralische und unmoralische Handlungen beeinflusst. Schließlich untersucht Studie 5 die potentielle Interaktion zweier haptischer Informationseinflüsse, indem Händereinigen und Gewichtsempfindungen kombiniert werden. Die Ergebnisse der Studien liefern eine Vielzahl neuer Befunde, die einem besseren Verständnis psychologischer Effekte körperlicher Reinheit dienen und insbesondere mit Blick auf das konzeptionelle Rahmenmodell der Embodied Cognition wichtige Erkenntnisse liefern.
4

Progression in cognitive-affective research by increasing ecological validity: A series of Virtual Reality studies.

Kisker, Joanna 18 February 2022 (has links)
The ultimate aim of psychological research is to disentangle everyday human functioning. Achieving this goal has always been limited by the necessity of balancing experimental control and ecological validity. Recent technical advances, however, reduce this trade-off immensely, perhaps even rendering it void: Sophisticated virtual reality (VR) systems provide not only high experimental control but also multidimensional and realistic stimuli, tasks, and experimental setups. Yet prior to applying VR as a standalone experimental method, an empirical foundation for its application needs to be established. To this end, this dissertation aims to shed light on whether and which changes in cognitive-affective standard findings result from increasing the ecological validity by means of VR paradigms. The four empirical studies included in this dissertation focus either on the affective or mnemonic processes and mechanisms occurring under immersive VR conditions compared to conventional laboratory setups. Study 1.1 investigated whether the electrophysiological correlates of the approach/avoidance dimension differ depending on the mode of presentation, i.e., immersive VR footage or a virtual 2D desktop. Study 2 was extended by a behavioral component. Full-body responses were enabled within this paradigm to examine holistic fear responses and to put to the test whether the respective electrophysiological responses translate from keystrokes to natural responses. With respect to the retrieval of such immersive experiences, Study 1.2 aimed to replicate the memory superiority effect found for VR conditions compared to conventional conditions. The generalizability of this effect will be examined using complex, multimodal scenes. Going one step further, Study 3 differentiated the retrieval mechanisms underlying VR-based or conventional laboratory engrams on the electrophysiological level. The well-established theta old/new effect served as a benchmark to check whether cognitive processes obtained under conventional conditions translate to VR conditions. The results of these studies are discussed with respect to whether and how increasing ecological validity alters the standard findings expected on the basis of the previous research background. Special attention will be paid to the differences between conventional laboratory setups and sophisticated VR setups with the aim to identify possible sources of the obtained deviations from standard findings. Such changes in the findings that overlap and exceed all studies beyond their primary focus, whether emotional or mnemonic, are discussed in terms of embodied simulations and the predictive coding hypothesis. A shared mental 3D default space is proposed as a possible source of fundamental differences between conventional and VR-based research outcomes. In particular, it will be demonstrated that conventional research approaches and findings may not only be amplified but fundamentally altered when translated to VR paradigms.
5

Individual Differences in Emotion Regulation Abilities: Action Orientation’s Impact on Intuition, Negativity Bias in Depression, and Self-Infiltration

Radtke, Elise L. 21 January 2020 (has links)
Using action orientation after failure as a measure of individual differences in emotion regulation abilities (ERA), this thesis’ studies investigated the impact of ERA on cognition, behavior, and own versus imposed goals differentiation. The first study used cortisol as a physiological stress marker to replicate the link between ERA and the ability to make intuitive judgments under stress. High ERA were associated with increased performance in an intuition task under stress. In contrast, when feeling no stress, low ERA were associated with increased performance in an intuition task. The second study showed that ERA can compensate for depression-associated biased processing of negative stimuli. This effect was present even at mild to moderate depression levels. Replicating earlier findings, the third study showed that ERA are associated with an increased ability to distinguish self-chosen from imposed goals. Most importantly, the study identified activation in the right medial prefrontal cortex as a neural correlate of identifying self-chosen goals, and activation in the anterior cingulate cortex, as a correlate of falsely identifying imposed goals as self-chosen ones. Altogether, these studies show the necessity to consider individual differences in ERA in stress, clinical, and motivational research. The findings are discussed with respect to three theories that relate to motivation and personality from behavioral and neurobiological perspectives, namely, Personality Systems Interaction Theory, Predictive and Reactive Control Systems Theory, and Self-Determination Theory.
6

Selbststeuerung und Leistung / Volitional Functions and Achievement

Hünniger, Frank 05 August 2008 (has links)
Vor dem Hintergrund der PSI-Theorie werden Fragen der Vorhersage von Leistung entwickelt. Neben einer kurzen Darstellung der Theorie werden zunächst zur Methodenexploration in 4 Experimenten im Stroop-Paradigma Fragen der Grundlagenforschung zum Stroop-Interferenz-Reduktions-Effekt (SIRE) durch nonverbale emotionale Primes beantwortet. In 3 weiteren Studien konnte gezeigt werden, dass Leistung mit der Interaktion aus Selbststeuerung insbesondere der Komponente Zielumsetzung und dem nichtreaktiven Maß der Stroop-Interferenz nach Leistungsprimes vorhergesagt werden kann. Es scheint Hinweise auf eine gewisse Gesetzmäßigkeit dieser Interaktion zu geben. Bei der Leistungsvorhersage wird eine invers sinusförmig verlaufende Charakteristik der Interaktion vermutet, die in 3 Studentenstichproben zum Problemlösen, zur Klausurleistung sowie zum Fortschritt bei Leistungszielen während eines Semesters untersucht werden konnte. Die wesentlichen Erkenntnisse der Vorhersage aus reaktiven Maßen (Selbststeuerung, insbesondere Willensbahnung) und nichtreaktiven Maßen (Intentionsgedächtnisnutzung) werden dargestellt. Implikationen für die Anwendung gehen in Richtung größerer Studien zur Erforschung dieser prädiktiven Interaktion. Dieses Muster ist relevant für die Anwendungswissenschaften Klinische Psychologie als auch die Arbeitspsychologie i.S. von persönlichkeitsfördernder Gestaltung der Arbeit.
7

Context Effects in Early Visual Processing and Eye Movement Control

Nortmann, Nora 29 April 2015 (has links)
There is a difference between the raw sensory input to the brain and our stable perception of entities in the environment. A first approach to investigate perception is to study relationships between properties of currently presented stimuli and biological correlates of perceptual processes. However, it is known that such processes are not only dependent on the current stimulus. Sampling of information and the concurrent neuronal processing of stimulus content rely on contextual relationships in the environment, and between the environment and the body. Perceptual processes dynamically adjust to relevant context, such as the current task of the organism and its immediate history. To understand perception, we have to study how processing of current stimulus content is influenced by such contextual factors. This thesis investigates the influence of such factors on visual processing. In particular, it investigates effects of temporal context in early visual processing and the effect of task context in eye movement control. To investigate effects of contextual factors on early visual processing of current stimulus content, we study neuronal processing of visual information in the primary visual cortex. We use real-time optical imaging with voltage sensitive dyes to capture neuronal population activity in the millisecond range across several millimeters of cortical area. To characterize the cortical layout concerning the mapping of orientation, previous to further investigations, we use smoothly moving grating stimuli. Investigating responses to this stimulus type systematically, we find independent encoding of local contrast and orientation, and a direct mapping of current stimulus content onto cortical activity (Study 1). To investigate the influence of the previous stimulus as context on processing of current stimulus content, we use abrupt visual changes in sequences of modified natural images. In earlier studies, investigating relatively fast timescales, it was found that the primary visual cortex continuously represents current input (ongoing encoding), with little interference from past stimuli. We investigate whether this coding scheme generalizes to cases in which stimuli change more slowly, as frequently encountered in natural visual input. We use sequences of natural scene contours, comprised of vertically and horizontally filtered natural images, their superpositions, and a blank stimulus, presented with 10 or 33 Hz. We show that at the low temporal frequency, cortical activity patterns do not encode the present orientations but instead reflect their relative changes in time. For example, when a stimulus with horizontal orientation is followed by the superposition of both orientations, the pattern of cortical activity represents the newly added vertical orientations instead of the full sum of orientations. Correspondingly, contour removal from the superposition leads to the representation of orientations that have disappeared rather than those that remain. This is in sharp contrast to more rapid sequences for which we find an ongoing representation of present input, consistent with earlier studies. In summary, we find that for slow stimulus sequences, populations of neurons in the primary visual cortex are no longer tuned to orientations within individual stimuli but instead represent the difference between consecutive stimuli. Our results emphasize the influence of the temporal context on early visual processing and consequentially on information transmission to higher cortical areas (Study 2). To study effects of contextual factors on the sampling of visual information, we focus on human eye movement control. The eyes are actively moved to sample visual information from the environment. Some traditional approaches predict eye movements solely on simple stimulus properties, such as local contrasts (stimulus-driven factors). Recent arguments, however, emphasize the influence of tasks (task context) and bodily factors (spatial bias). To investigate how contextual factors affect eye movement control, we quantify the relative influences of the task context, spatial biases and stimulus-driven factors. Participants view and classify natural scenery and faces while their eye movements are recorded. The stimuli are composed of small image patches. For each of these patches we derive a measure that quantifies stimulus-driven factors, based on the image content of a patch, and spatial viewing biases, based on the location of the patch. Utilizing the participants’ classification responses, we additionally derive a measure, which reflects the information content of a patch in the context of a given task. We show that the effect of spatial biases is highest, that task context is a close runner-up, and that stimulus-driven factors have, on average, a smaller influence. Remarkably, all three factors make independent and significant contributions to the selection of viewed locations. Hence, in addition to stimulus-driven factors and spatial biases, the task context contributes to visual sampling behavior and has to be considered in a model of human eye movements. Visual processing of current stimulus content, in particular visual sampling behavior and early processing, is inherently dependent on context. We show that already in the first cortical stage, temporal context strongly affects the processing of new visual information and that visual sampling by eye movements is significantly influenced by the task context, independently of spatial factors and stimulus-driven factors. The empirical results presented provide foundations for an improved theoretical understanding of the role of context in perceptual processes.
8

I can't let go: Personality, Behavioral, and Neural Correlates of Persistent, Intrusive Thought in Depression

Eggert, Lucas 24 April 2013 (has links)
Though a major illness in modern society, depression is still not completely understood. A number of empirical observations point to the importance of basic cognitive processes as well as personality variables as antecedents of a depressive disorder. In this work it is argued that “state orientation”, a personality style characterized by the inability to actively influence one’s focus of thought, plays an important role in the development of at least some forms of major depressive disorder. In the present work, it is suggested that (1) state-oriented cognitions are equivalent to sustained information processing, that (2) depressed individuals are characterized in particular by state-oriented cognitions related to prior failure experiences, that (3) sustained processing of affective information will interfere with normal executive cognitive functioning in depressed individuals resulting in impairments of normal behavior, and that (4) both sustained information processing and “affective interference” will be associated with specific dysfunctional patterns of brain activity in depressed individuals. In the first chapter of this thesis, theorizing pertaining to “action control” and the relationship between action control and state orientation are reviewed. After having established the potential functional significance of state-oriented cognitions, their possible link to depression is developed by introducing the “degenerated-intention hypothesis”. Afterwards, the role of state orientation in the advent of the depressive state is discussed against the background of the “functional helplessness” model of depression. Next, recent empirical findings related to executive dysfunction associated with state-oriented cognitions in major depressive disorder and related dysfunctional patterns of brain activity are reviewed. By considering evidence from studies on executive functioning, brain imaging, and neurophysiological studies, support is found for a possible frontocingulate dysfunction associated with a state-oriented cognitive style underlying a major depressive disorder. Consistent with the proposed link between depression and state orientation, in the second chapter of the thesis, Studies 1a – 1c demonstrate that subclinically and clinically depressed individuals are specifically characterized by failure-related state orientation. Moreover, the results of Study 2, described in Chapter 3, reveal that sustained processing of affectively valenced information may indeed interfere with subsequent executive cognitive functioning, especially in individuals demonstrating relatively high levels of depression. Finally, in line with the idea that sustained information processing and affective interference will be related to an individual’s level of state orientation and will be reflected in specific patterns of neural activity, Study 3, presented in Chapter 4, provides considerable evidence for disturbed brain function in clinically depressed individuals during processing of affective information as well as subsequent executive cognitive functioning and its relation to state-oriented thought. The current research supports the idea that state orientation, in particular its failure-focused form, is a crucial process involved in the development and maintenance of a depressive disorder. Specifically, the present findings suggest that certain forms of major depressive disorder are associated with sustained processing of affective information and with the resulting affective interference with executive cognitive functioning. Findings further suggest that sustained information processing is experienced by affected individuals as ruminative, state-oriented thought on past aversive experiences, and that both sustained information processing and affective interference are associated with distinct patterns of brain activity, which are related to early stimulus evaluation, conflict monitoring, and conflict resolution. The processes possibly underlying some forms of depression, as proposed in this thesis, comprise what may be called “the spinning mind”, whose important functional significance is to hinder an individual from adaptive behavior by impairing the ability to direct thought. Although state orientation may therefore appear to be maladaptive per se, it may be argued instead that this mode of action control is also an adaptive process as long as critical limits of certain parameters are met and the spinning mind is prevented. These and similar considerations are addressed in the concluding discussion in Chapter 5.
9

Evaluation neuroprotektiver Strategien am Beispiel ausgewählter neurodegenerativer Erkrankungen: Amyotrophe Lateralsklerose und Alkoholabhängigkeit / Evaluating neuroprotective strategies in neurodegenerative diseases: amyotrophic lateral sclerosis and alcohol dependence

Bartels, Claudia 02 May 2007 (has links)
No description available.

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