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Vision is a multistep process that begins when light stimulates cells in the retina, with multiple processes quickly cascading throughout the brain, providing new information to inform potential actions. Complicating this is the fact that vision does not only proceed unidirectionally, or bottom-up, but in every region of the brain, reentrant or top-down signals influence earlier stages by feeding activity back to previously activated brain regions. This reentrant processing is both iterative and dynamic. In this chapter I review several new developments in dot-based masking that serve as tools for studying how this dynamic flow of information helps us to make sense of the visual environment. Four-dot object-substitution masking, which arises at the whole-object level, is contrasted with two newly discovered edge-based masking effects (object trimming and object binding). I then review the evidence which shows that by examining these effects, researchers are gaining a more solid understanding of the role reentrant processes play in conscious awareness, the role reentrant processes play in feature binding, the level at which objects are processed when the reentrant sweep begins, and whether reentrant pathways carry top-down information about meaning and cultural expectations that can guide the edge-assembly process before objects have even been recognized. [ABSTRACT FROM AUTHOR]

Shadow detection and removal is important to deal with vision based mobile robot localization. The shadow cast by objects within environment which a mobile robot moves can lead to inaccurate object feature extraction and an erroneous scene analysis. To remove the shadow of an object, the difference image between the original and background image is usually used. However, as the shadow area caused by the light source comes out, it should be removed to obtain the accurate object image. In this paper, we used the surveillance cameras installed at the room ceiling for vision based robot localization. Time-consuming algorithm is difficult applied for the mobile robot localization. Therefore, we proposed a fast shadow removal algorithm based the HSV color space. Generally, the shadow removal method by the HSV color space is speedy but not enough to find shadow property compared with other methods. Shadow mask and HSV color space are used together to detect the shadow region. Experimental results show that the proposed method is simple to understand, can detect and remove shadow effectively for a mobile robot localization. [ABSTRACT FROM AUTHOR]

Abstract: Even with unimpaired vision, observers sometimes fail to see things right before their open eyes. A typical example is the attentional blink effect, a period in which observers are unable to detect a target item in a sequence of stimuli, for as long as the previous one occupies their mind. Having considered a range of mechanisms proposed to explain attentional blink effect, we arrive at our preferred explanation, which ascribes the effect to a contextually motivated imbalance in the allocation of attentional resources between earlier and later target information. We interpret in this perspective our data on how the attentional blink effect changes as a result of practice. [Copyright &y& Elsevier]

The article examines iconic store readout of retarded and nonretarded individuals employing a backward visual masking paradigm. The subjects were required to report tachistoscopically presented linear arrays of letters differing with respect to the number of letters per array. The study suggests that it is possible to assess the efficiency of the iconic store readout.

An abstract of the article "Visual Masking Approaches to Visual Awareness," by Stephen L. Macknik is presented.