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.

Objective: Saliency-based theories assume that stimulus features (luminance, edges, texture) shape the hierarchy of perception. Predictions about human viewing behavior point out that highly salient objects or regions of a picture will be perceived first (e.g. Itti et al. 2001). Not much attention is paid to top-down factors such as emotion, motivation and other cognitive functions. The present study analyses the influence of the emotional status on visual perception in free-viewing tasks. Following the hypotheses of the study even in artificial contexts such as viewing neutral pictures in an experiment, top-down factors, such as emotion might influence length of fixation and the number of fixations and saccades. Approaches of visual perception and perception in general should focus more on the individual cognitive aspects of this process. Method: In an eyetracking-study 91 participants viewed neutral and emotional relevant pictures without any task. Five emotional pictures (crime, murder, babies), which were taken from the IAPS (Lang, Bradley & Cuthbert, 2005) were followed by one neutral picture (forest, grass) taken from studies of Peters et al (2005) and Einhäuser et al. (2003). Altogether the subjects viewed 130 pictures. Results: There were significant differences in viewing behavior concerning the neutral pictures subject to the emotional condition. When presented in context with emotional pictures, neutral pictures were fixated longer and less frequently in comparison to the neutral condition. There is evidence to suggest that the emotional context influenced visual attention concerning the neutral pictures in that way that attention for the neutral material was reduced in the context of highly arousing emotional pictures. This leads to the conclusion, that even in experimental setups with simple neutral stimuli the process of visual perception is influenced top-down.

The real-world sensorimotor paradigm is based on the premise that sufficient ecological complexity is a prerequisite for inducing naturally relevant sensorimotor relations in the experimental context. The aim of this thesis is to embed visual attention research within the real-world sensorimotor paradigm using an innovative mobile gaze-tracking system (EyeSeeCam, Schneider et al., 2009). Common laboratory set-ups in the field of attention research fail to create natural two-way interaction between observer and situation because they deliver pre-selected stimuli and human observer is essentially neutral or passive. EyeSeeCam, by contrast, permits an experimental design whereby the observer freely and spontaneously engages in real-world situations. By aligning a video camera in real time to the movements of the eyes, the system directly measures the observer’s perspective in a video recording and thus allows us to study vision in the context of authentic human behaviour, namely as resulting from past actions and as originating future actions. The results of this thesis demonstrate that (1) humans, when freely exploring natural environments, prefer directing their attention to local structural features of the world, (2) eyes, head and body perform distinct functions throughout this process, and (3) coordinated eye and head movements do not fully stabilize but rather continuously adjust the retinal image also during periods of quasi-stable “fixation”. These findings validate and extend the common laboratory concept of feature salience within whole-body sensorimotor actions outside the laboratory. Head and body movements roughly orient gaze, potentially driven by early stages of processing. The eyes then fine-tune the direction of gaze, potentially during higher-level stages of visual-spatial behaviour (Studies 1 and 2). Additional head-centred recordings reveal distinctive spatial biases both in the visual stimulation and the spatial allocation of gaze generated in a particular real-world situation. These spatial structures may result both from the environment and form the idiosyncrasies of the natural behaviour afforded by the situation. By contrast, when the head-centred videos are re-played as stimuli in the laboratory, gaze directions reveal a bias towards the centre of the screen. This “central bias” is likely a consequence of the laboratory set-up with its limitation to eye-in-head movements and its restricted screen (Study 3). Temporal analysis of natural visual behaviour reveals frequent synergistic interactions of eye and head that direct rather than stabilize gaze in the quasi-stable eye movement periods following saccades, leading to rich temporal dynamics of real-world retinal input (Study 4) typically not addressed in laboratory studies. Direct comparison to earlier data with respect to the visual system of cats (CatCam), frequently taken as proxy for human vision, shows that stabilizing eye movements play an even less dominant role in the natural behaviour of cats. This highlights the importance of realistic temporal dynamics of vision for models and experiments (Study 5). The approach and findings presented in this thesis demonstrate the need for and feasibility of real- world research on visual attention. Real-world paradigms permit the identification of relevant features triggered in the natural interplay between internal-physiological and external-situational sensorimotor factors. Realistic spatial and temporal characteristics of eye, head and body interactions are essential qualitative properties of reliable sensorimotor models of attention but difficult to obtain under laboratory conditions. Taken together, the data and theory presented in this thesis suggest that visual attention does not represent a pre-processing stage of object recognition but rather is an integral component of embodied action in the real world.

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.

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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.