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Contains fulltext : 231585.pdf (publisher's version ) (Open Access), The purpose of the present note is to draw attention to the potential role of a recently discovered visual illusion in creating traffic accidents. The illusion consists in a compelling and immediate experience that the space behind an occluding object in the foreground is empty. Although the illusion refers to a region of space, which is invisible due to occlusion (a blind spot), there is evidence to suggest that it is nevertheless driven by visual mechanisms and that it can be just as deceptive and powerful as ordinary visual illusions. We suggest that this novel illusion can make situations involving blind spots in a road user's field of view even more dangerous than one would expect based on the lack of visibility by itself. This could be because it erroneously makes the road user feel that (s)he has actually seen everything there is to see, and thus has verified that the blind spot is empty. This hypothesis requires further testing before definitive conclusions can be drawn, but we wish to make researchers and authorities involved in the analysis of traffic accidents and on-the-spot crash investigations aware of its potential role in order to encourage registration of relevant data and facilitate further research.

"Virussen zijn biologisch alternatief voor gewasbeschermingsmiddelen" : KU Leuven en ILVO voeren onderzoek naar gewasbescherming met fagen ; "Gekke wortels overwinnen is geen hopeloze zaak" : ILVO-onderzoeker Johan Van Vaerenbergh strijdt tegen gekke wortels ; Resultaten van enquête 'Bestijding van gekke wortels' ; 8 vragen over fagen ; Brug tussen onderzoek en praktijk.

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Visual perception in individuals with autism spectrum disorder (ASD) is often debated in terms of enhanced local and impaired global perception. Deficits in global motion perception seem to support this characterization, although the evidence is inconsistent. We conducted a large meta-analysis on global motion, combining 48 articles on biological and coherent motion. Results provide evidence for a small global motion processing deficit in

In his 1975 paper, Bozzi presented a sample of transparency effects obtained with achromatic line drawings, that is with drawings made only of black lines and dots. Commenting his work, I will follow the structure of his paper. Without the time to run appropriate experi - ments, and having shown the demos proposed in this work only to a few expert observers, whose descriptions are however consistent with my own impressions, when describing the effects I will rely on what I see, aware of the need for proper experiments to be carried out.

Since its initial development, the embedded figures test (EFT) has been used extensively to measure local–global perceptual style. However, little is known about the perceptual factors that influence target detection. The current study aimed to investigate disembedding in children with and without ASD, aged 8–15 years, using the newly developed, stimulus-controlled L-EFT, M-EFT and D-EFT. Firstly, results revealed superior disembedding for children with ASD, irrespective of the type of target or embedding context, although the ASD group took more time in both the M-EFT and D-EFT. Secondly, the number of target lines continuing into the context proved more of a hindrance for the controls. Taken together, these findings provide strong evidence to support the notion of superior disembedding in ASD.

Performance on the Embedded Figures Test (EFT) has been interpreted as a reflection of local/global perceptual style, weak central coherence and/or field independence, as well as a measure of intelligence and executive function. The variable ways in which EFT findings have been interpreted demonstrate that the construct validity of this measure is unclear. In order to address this lack of clarity, we investigated to what ext

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Predictive coding has recently been welcomed as a fruitful framework to understand autism spectrum disorder. Starting from an account centered on deficient differential weighting of prediction errors (based in so-called precision estimation), we illustrate that individuals with autism have particular difficulties with separating signal from noise, across different tasks. Specifically, we discuss how deficient precision-setting is detrimental for learning in unstable environments, for context-dependent assignment of salience to inputs, and for robustness in perception, as illustrated in coherent motion paradigms.

Background. The Embedded Figures Test (EFT, developed by Witkin and colleagues (1971)) has been used extensively in research on individual differences, particularly in the study of autism spectrum disorder. The EFT was originally conceptualized as a measure of field (in)dependence, but in recent years performance on the EFT has been interpreted as a measure of local versus global perceptual style. Although many have used the EFT to measure perceptual style, relatively few have focused on understanding the stimulus features that cause a shape to become embedded. The primary aim of this work was to investigate the relation between the strength of embedding and perceptual grouping on a group level. Method. New embedded figure stimuli (both targets and contexts) were developed in which stimulus features that may influence perceptual grouping were explicitly manipulated. The symmetry, closure and complexity of the target shape were manipulated as well as its good continuation by varying the number of lines from the target that continued into the context. We evaluated the effect of these four stimulus features on target detection in a new embedded figures task (Leuven Embedded Figures Test, LEFT) in a group of undergraduate psychology students. The results were then replicated in a second experiment using a slightly different version of the task. Results. Stimulus features that influence perceptual g

A large body of research reports individual differences in local and global visual processing in relation to expertise, culture and psychopathology. However, recent research has suggested that various different measures of local-global processing are not strongly associated with one another, calling its construct validity into question. The current study sought to further explore the validity of local-global processing biases in perception by developing three tasks based on two existing paradigms: the Embedded Figures Test (EFT) and the Navon hierarchical letters task. The newly developed tasks aimed to control for stimulus and response factors that may have impacted upon the reliability of previous research. They were administered to a large sample of undergraduate students (N > 100). The results of two new versions of the EFT indicated that disembedding performance is influenced by the structure of the embedding context. In addition, global precedence and interference in the Navon task remained present even when local attentional approaches to global hierarchical stimuli were restricted. Inter-task correlations within the EFT were high but low between the EFT and the Navon task, lending support to the notion that local-global processing is not a monolithic construct, but representative of a number of distinct perceptual abilities and biases. Future research may use these task distinctions to pinpoint more precisely which aspects of perceptual processing characterise specific (clinical) participant populations.

During the GUINEVERE FP6 European project (2006-2011), the zero-power VENUS water-moderated reactor was modified into VENUS-F, a mockup of lead cooled fast spectrum system with solid components that can be operated in both critical and subcritical mode. The Fast Reactor Experiments for hybrid Applications (FREYA) FP7 project was launched in 2011 to support the designs of the MYRRHA Accelerator Driven System (ADS) and the ALFRED Lead Fast Reactor (LFR). Three VENUS-F critical core configurations, simulating the complex MYRRHA core design and one configuration devoted to the LFR ALFRED core conditions were investigated in 2015. The MYRRHA related cores simulated step by step design peculiarities like the BeO reflector and in pile sections. For all of these cores the fuel assemblies were of a simple design consisting of 30 % enriched metallic uranium, lead rodlets to simulate the coolant and Al2O3 rodlets to simulate the oxide fuel. Fission rate ratios of minor actinides such as Np-237, Am-241 as well as Pu-239, Pu-240, Pu-242 and U-238 to U-235 were measured in these VENUS-F critical assemblies with small fission chambers in specially designed locations, to determine the spectral indices in the different neutron spectrum conditions. The measurements have been analyzed using advanced computational tools including deterministic and stochastic codes and different nuclear data sets like JEFF-3.1, JEFF-3.2, ENDF/B7.1, ENDF/B6.8, JENDL-4.0 and TENDL-2014. The analysis of the C/E discrepancies will help to improve the nuclear data in the specific energy region of fast neutron reactor spectra.

Contains fulltext : 158787.pdf (publisher's version ) (Open Access)

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Contains fulltext : 161838.pdf (publisher's version ) (Open Access)

Accelerator Driven systems (ADS) along with traditional fast reactors are under study as a possible mean to transmute minor actinides (MA) and long lived fission products (LLFP). The Fast Reactor Experiments for hybrid Applications (FREYA [1]) European FP7 project was launched in 2011 to support the designs of the ADS MYRRHA [2] and lead fast reactor (LFR) ALFRED [3]. The main aim of the FREYA project is to validate reactivity monitoring methods in sub-critical cores, but essential efforts were also devoted to the validation of MA data in several VENUS-F zero power critical assemblies simulating LFR and MYRRHA critical cores. In these critical VENUS-F assemblies, fission rate ratios of MA such as Np-237, Am-241 as well as Pu-239, Pu-240, Pu-242 and U-238 to U-235 were measured using calibrated fission chambers. The measurements were analyzed using advanced computational tools including deterministic and stochastic codes and recent nuclear data sets. The C/E results of these fission rate ratios in several fast neutron lead cooled VENUS-F zero power assemblies are presented and discussed.