1,530 research outputs found

    TMS over V5 disrupts motion prediction

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    Given the vast amount of sensory information the brain has to deal with, predicting some of this information based on the current context is a resource-efficient strategy. The framework of predictive coding states that higher-level brain areas generate a predictive model to be communicated via feedback connections to early sensory areas. Here, we directly tested the necessity of a higher-level visual area, V5, in this predictive processing in the context of an apparent motion paradigm. We flashed targets on the apparent motion trace in-time or out-of-time with the predicted illusory motion token. As in previous studies, we found that predictable in-time targets were better detected than unpredictable out-of-time targets. However, when we applied functional magnetic resonance imaging-guided, double-pulse transcranial magnetic stimulation (TMS) over left V5 at 13–53 ms before target onset, the detection advantage of in-time targets was eliminated; this was not the case when TMS was applied over the vertex. Our results are causal evidence that V5 is necessary for a prediction effect, which has been shown to modulate V1 activity (Alink et al. 2010). Thus, our findings suggest that information processing between V5 and V1 is crucial for visual motion prediction, providing experimental support for the predictive coding framework

    Engineering data compendium. Human perception and performance. User's guide

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    The concept underlying the Engineering Data Compendium was the product of a research and development program (Integrated Perceptual Information for Designers project) aimed at facilitating the application of basic research findings in human performance to the design and military crew systems. The principal objective was to develop a workable strategy for: (1) identifying and distilling information of potential value to system design from the existing research literature, and (2) presenting this technical information in a way that would aid its accessibility, interpretability, and applicability by systems designers. The present four volumes of the Engineering Data Compendium represent the first implementation of this strategy. This is the first volume, the User's Guide, containing a description of the program and instructions for its use

    Exploring The Illusion Of Transparency When Lying And Truth-Telling: The Impact Of Age, Self-Consciousness, And Framing

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    Individuals often overestimate the ability of others to accurately determine their internal states. This illusion of transparency has been shown to manifest itself in everyday scenarios, including when people are asked to estimate if others can tell when they are lying. Yet it has not been observed when truth-telling, nor investigated developmentally. The current experiments tested for an illusion of transparency when individuals were truth-telling and lying and investigated how a participant\u27s age, dispositional self-consciousness, situational self-awareness and how questions were framed impacted the strength and prevalence of the illusion of transparency. In Experiments 1 and 2, children and adolescents (ages 9 to 17; n = 34) and undergraduates (n = 91) participated in a lie/truth-telling game, during which participants made true and false statements corresponding to past real-life events. Half of their statements were mock video recorded to alter their state of situational, public self-awareness. Participants estimated the transparency of their statements while other players judged the veracity. When estimating transparency, participants were asked to determine the number of other players who thought they were telling the truth or the number of others who thought they were lying. In Experiment 3, 135 undergraduate students played the same lie/truth-telling game, but the situational self-awareness manipulation varied between subjects and a mirror condition was added to investigate situational, private self-awareness. Results from the studies provide evidence that an illusion of transparency exists among truth-tellers. Participants in all three studies overestimated the number of others who would believe them when telling the truth. However, an illusion of transparency was not observed when participants were lying. There was a consistent interaction between statement veracity and framing. When telling the truth, participant\u27s predicted more transparency when questioned with the truth frame than the lie frame, but when lying participant\u27s predicted more transparency when questioned with the lie frame. Differences in the illusion were not impacted by the grade level of participants, likely due to an absence of developmental differences in self-consciousness. Child and adolescent participants experienced a greater illusion of transparency when self-aware; however this did not replicate with adults. Implications and directions for future research are discussed

    Spacing affects some but not all visual searches: Implications for theories of attention and crowding

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    We investigated the effect of varying interstimulus spacing on an upright among inverted face search and a red–green among green–red bisected disk search. Both tasks are classic examples of serial search; however, spacing affects them very differently: As spacing increased, face discrimination performance improved significantly, whereas performance on the bisected disks remained poor. (No effect of spacing was observed for either a red among green or an L among + search tasks, two classic examples of parallel search.) In a second experiment, we precued the target location so that attention was no longer a limiting factor: Both serial search tasks were now equally affected by spacing, a result we attribute to a more classical form of crowding. The observed spacing effect in visual search suggests that for certain tasks, serial search may result from local neuronal competition between target and distractors, soliciting attentional resources; in other cases, serial search must occur for another reason, for example, because an item-by-item, attention-mediated recognition must take place. We speculate that this distinction may be based on whether or not there exist neuronal populations tuned to the relevant target–distractor distinction, and we discuss the possible relations between this spacing effect in visual search and other forms of crowding

    Artificially created stimuli produced by a genetic algorithm using a saliency model as its fitness function show that Inattentional Blindness modulates performance in a pop-out visual search paradigm

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    Salient stimuli are more readily detected than less salient stimuli, and individual differences in such detection may be relevant to why some people fail to notice an unexpected stimulus that appears in their visual field whereas others do notice it. This failure to notice unexpected stimuli is termed 'Inattentional Blindness' and is more likely to occur when we are engaged in a resource-consuming task. A genetic algorithm is described in which artificial stimuli are created using a saliency model as its fitness function. These generated stimuli, which vary in their saliency level, are used in two studies that implement a pop-out visual search task to evaluate the power of the model to discriminate the performance of people who were and were not Inattentionally Blind (IB). In one study the number of orientational filters in the model was increased to check if discriminatory power and the saliency estimation for low-level images could be improved. Results show that the performance of the model does improve when additional filters are included, leading to the conclusion that low-level images may require a higher number of orientational filters for the model to better predict participants' performance. In both studies we found that given the same target patch image (i.e. same saliency value) IB individuals take longer to identify a target compared to non-IB individuals. This suggests that IB individuals require a higher level of saliency for low-level visual features in order to identify target patches

    Predictive coding as a model of the V1 saliency map hypothesis

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    The predictive coding/biased competition (PC/BC) model is a specific implementation of predictive coding theory that has previously been shown to provide a detailed account of the response properties of orientation tuned cells in primary visual cortex (V1). Here it is shown that the same model can successfully simulate psy-chophysical data relating to the saliency of unique items in search arrays, of contours embedded in random texture, and of borders between textured regions. This model thus provides a possible implementation of the hypothesis that V1 generates a bottom-up saliency map. However, PC/BC is very different from previous mod-els of visual salience, in that it proposes that saliency results from the failure of an internal model of simple elementary image components to accurately predict the visual input. Saliency can therefore be interpreted as a mechanism by which prediction errors attract attention in an attempt to improve the accuracy of the brain’s internal representation of the world

    Deep learning-based vessel detection from very high and medium resolution optical satellite images as component of maritime surveillance systems

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    This thesis presents an end-to-end multiclass vessel detection method from optical satellite images. The proposed workflow covers the complete processing chain and involves rapid image enhancement techniques, the fusion with automatic identification system (AIS) data, and the detection algorithm based on convolutional neural networks (CNN). The algorithms presented are implemented in the form of independent software processors and integrated in an automated processing chain as part of the Earth Observation Maritime Surveillance System (EO-MARISS).In der vorliegenden Arbeit wird eine Methode zur Detektion von Schiffen unterschiedlicher Klassen in optischen Satellitenbildern vorgestellt. Diese gliedert sich in drei aufeinanderfolgende Funktionen: i) die Bildbearbeitung zur Verbesserung der Bildeigenschaften, ii) die Datenfusion mit den Daten des Automatischen Identifikation Systems (AIS) und iii) dem auf „Convolutional Neural Network“ (CNN) basierenden Detektionsalgorithmus. Die vorgestellten Algorithmen wurden in Form eigenständiger Softwareprozessoren implementiert und als Teil des maritimen Erdbeobachtungssystems integriert

    Inside the brain of an elite athlete: The neural processes that support high achievement in sports

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    Events like the World Championships in athletics and the Olympic Games raise the public profile of competitive sports. They may also leave us wondering what sets the competitors in these events apart from those of us who simply watch. Here we attempt to link neural and cognitive processes that have been found to be important for elite performance with computational and physiological theories inspired by much simpler laboratory tasks. In this way we hope to inspire neuroscientists to consider how their basic research might help to explain sporting skill at the highest levels of performance

    Psychophysiology of False Memories in a Deese-Roediger-McDermott Paradigm with Visual Scenes

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    Remembering something that has not in fact been experienced is commonly referred to as false memory. The Deese-Roediger-McDermott (DRM) paradigm is a well-elaborated approach to this phenomenon. This study attempts to investigate the peripheral physiology of false memories induced in a visual DRM paradigm. The main research question is whether false recognition is different from true recognition in terms of accompanying physiological responses
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