Visual selection as an object-oriented mechanism: an ecological perspective towards the primacy of objects over space

The visual world consists of objects. Planning or performing actions requires some form of engagement with an object. This requirement has shaped our perceptual systems to be highly tuned to ‘objecthood’ and construct objects from minimal available information. This project aimed to explore to what extent the importance of objects influences visual selection: the mechanism that prioritises the necessary information subsets in order to perform an action, and investigate on what basis this information is prioritised. Current visual selection theories argue prioritisation is accomplished as a combination between space-based and object-based mechanisms, with space having a prime role in how information is selected from the environment. This project proposes an alternative view, suggesting selection is a fully object-oriented mechanism and space-based effects are a consequence of object-based selection. This possibility was tested in three empirical chapters with the use of cueing paradigms, in the context of immediate perceptual decisions (luminance change identification), and colour change detection involving visuo-spatial short term memory. The key premise is that there is an intrinsic link between the spatial separation of any two points and the likelihood they belong to the same object. If these points are perceived to be within the same object, visual selection is not affected by the distance between them and they are equally prioritised for action. Prioritisation level decreases with increasing distance only when this likelihood of object- belongingness is low, because points closer together have a higher probability to originate from the same object. The current work tested this premise by varying independently object-belongingness and spatial proximity of cue-target stimuli pairs. Results indicated that visual selection is fully object-oriented and can be distance-independent. It is proposed that the perceptual system assesses the probability that information is integrated into potential objects, and then prioritises selection based on this object-belongingness probability

The objects of visuo-spatial short term memory: perceptual organisation and change detection

We used a color change-detection paradigm where participants were required to remember colors of six equally-spaced circles. Items were superimposed on a background so as to perceptually group them either within i) an intact ring-shaped object, ii) a physically segmented but perceptually completed ring-shaped object, or iii) a corresponding background segmented into three arc-shaped objects. A non-predictive cue at the location of one of the circles was followed by the memory items, which in turn were followed by a test display containing a probe indicating the circle to be judged same/different. Reaction times for correct responses revealed a same-object advantage; correct responses were faster to probes on the same object as the cue compared to equidistant probes on a segmented object. This same-object advantage was identical for physically and perceptually completed objects, but was only evident in reaction times, and not in accuracy measures. Not only, therefore, is it important to consider object-level perceptual organisation of stimulus elements when assessing the influence of a range of factors (e.g., number and complexity of elements) in visuo-spatial short-term memory, but a more detailed picture of the structure of information in memory may be revealed by measuring speed as well as accuracy

Mineral content and some optical properties of aloe vera juice

Introduction: Aloe (Aloe barbadensis Miller) is the most used medicinal plant in the world. Many of its beneficial properties are due to the presence of proteins, carbohydrates, amino acids, trace elements, etc. in the gel found in its leaves. It is part of various nutritional supplements, juices, cosmetic products, etc.Aim: The aim of the present study is to compare the elemental composition and fluorescence spectra of a natural aloe vera gel and one with different additives.Materials and Methods: The present study investigated and compared two types of commercial products, pure aloe vera gel and aloe vera supplemented with other plant species (aloe vera &). The content of some minerals in the two products was analyzed by flame atomic absorption spectrometry (FAAS). A fiber optic spectrometer was used to measure the fluorescence spectrum of the studied samples. Results: The emission peaks of the fluorescence spectrum of the samples are due to the content of phenolic compounds and antioxidants. Addition of honey, agave syrup, and acai puree to aloe vera gel resulted in a significant change in Mg and Fe contents, while Mn, Zn, and Cu were less affected. Conclusion: Both tested aloe vera gel products (with and without additives) showed the presence of phenolic compounds, antioxidants, and high concentrations of magnesium

An improved definition of official excess winter mortality statistics as the basis for detailed analysis and monitoring

In official statistics, excess winter mortality, the number of additional deaths in a winter period, is typically defined as the difference between mortality in a winter period relative to the nonwinter periods before and after. We note two limitations of this approach: (1) the data for the period after winter is available only later, so estimates of excess winter mortality are not timely; (2) unusually high or low numbers of deaths in the non-winter periods can affect estimates. We propose an alternative statistic based on the application of standard seasonal adjustment procedures. We compare the approaches and present some illustrative analyses. The new statistic provides a more objective and timely official series, but is susceptible to revisions, which are shown to be small in practice. We recommend it as the basis of more detailed monitoring and modelling