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Short answer Generally, a few months of active, guided training. Background Based on an article from a guide cane instructor who is a cane traveler himself, I can answer the question as follows: First off - it depends on at least three important variables; The student's background; The student's aptitude; the amount of time available to the student. ...


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Assuming you are talking about the ability of the visual system to resolve spatial detail (resolution, if you wish), then your question is on visual acuity as a function of eccentricity on the retina (Fig. 1). Due to the densely packed cones at the fovea (corresponding to the central field of view (FOV), see Fig. 1), visual acuity (VA) is the greatest at ...


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At least three things play a role here: Camouflage: the panda looks like the snowman in shape and coloring. Further, the ears of the panda are the buttons of the snowmen behind, i.e. the panda partly merges with the 'background' snowmen; Clutter: there are simply many, many snowmen; Distracters: The colored hats and other attributes are more salient and ...


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A nice illustrative image of how the photoreceptors connect to the retinal ganglion cell (RGC), and thereby facilitate the center-surround structure is provided in figure 1 below. It shows a cross section through the retina. Fig. 1. Photoreceptor organization and connections to the retinal ganglion cell. source: McGill University The receptive fields ...


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In the retina, the neurons that guide the visual signal to the brain, the retinal ganglion cells (RGCs), process contrast. The receptive fields (RFs) of these cells exhibit a so-called center-surround organization (Fig. 1). They integrate the signal from multiple cones in the retina. ON RGCs fire when their RF is illuminated in the center (the central cone ...


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The short answer is that it is not necessarily easier to read black on white. Contrast is more important in lightness and colour, it just so happens that black and white is the highest contrast. So its no accident that most books are in black and white. There is a plethora of research on perceptual processing which is easily found on google scholar if you ...


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As Waldemar said, it is has a natural reason. During long evolution the eyes are adopted to acquire information through shadows around the objects, but it works also in reverted mode (light object on a dark background). However it is understood that the eye cannot work in two modes at the same time (normal and reverted), so black text on light background is ...



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