Separate processing of texture and form in the ventral stream : evidence from fMRI and visual agnosia.

Real-life visual object recognition requires the processing of more than just geometric (shape, size, and orientation) properties. Surface properties such as color and texture are equally important, particularly for providing information about the material properties of objects. Recent neuroimaging research suggests that geometric and surface properties are dealt with separately, within the lateral occipital cortex (LOC) and the collateral sulcus (CoS), respectively. Here we compared objects that either differed in aspect ratio or in surface texture only, keeping all other visual properties constant. Results on brain-intact participants confirmed that surface texture activates an area in the posterior CoS, quite distinct from the area activated by shape within LOC. We also tested two patients with visual object agnosia, one of whom (DF) performed well on the texture task but at chance on the shape task, while the other (MS) showed the converse pattern. This behavioral double dissociation was matched by a parallel neuroimaging dissociation, with activation in CoS but not LOC in patient DF, and activation in LOC but not CoS in patient MS. These data provide presumptive evidence that the areas respectively activated by shape and texture play a causally necessary role in the perceptual discrimination of these features

Trans-saccadic priming in hemianopia: sighted-field sensitivity is boosted by a blind-field prime

We experience visual stability despite shifts of the visual array across the retina produced by eye movements. A process known as remapping is thought to keep track of the spatial locations of objects as they move on the retina. We explored remapping in damaged visual cortex by presenting a stimulus in the blind field of two patients with hemianopia. When they executed a saccadic eye movement that would bring the stimulated location into the sighted field, reported awareness of the stimulus increased, even though the stimulus was removed before the saccade began and so never actually fell in the sighted field. Moreover, when a location was primed by a blind-field stimulus and then brought into the sighted field by a saccade, detection sensitivity for near-threshold targets appearing at this location increased dramatically. The results demonstrate that brain areas supporting conscious vision are not necessary for remapping, and suggest visual stability is maintained for salient objects even when they are not consciously perceived

Archive of Darkness:William Kentridge's Black Box/Chambre Noire

Situating itself in histories of cinema and installation art, William Kentridge's Black Box/Chambre Noire (2005) raises questions about screens, exhibition space, site-specificity and spectatorship. Through his timely intervention in a debate on Germany’s colonial past, Kentridge’s postcolonial art has contributed to the recognition and remembrance of a forgotten, colonial genocide. This article argues that, by transposing his signature technique of drawings for projection onto a new set of media, Kentridge explores how and what we can know through cinematic projection in the white cube. In particular, his metaphor of the illuminated shadow enables him to animate archival fragments as shadows and silhouettes. By creating a multi-directional archive, Black Box enables an affective engagement with the spectres of colonialism and provides a forum for the calibration of moral questions around reparation, reconciliation and forgiveness

Preservation of Auditory P300-Like Potentials in Cortical Deafness

The phenomenon of blindsight has been largely studied and refers to residual abilities of blind patients without an acknowledged visual awareness. Similarly, “deaf hearing” might represent a further example of dissociation between detection and perception of sounds

Roles of contour and surface processing in microgenesis of object perception and visual consciousness

Developments in visual neuroscience and neural-network modeling indicate the existence of separate pathways for the processing of form and surface attributes of a visual object. In line with prior theoretical proposals, it is assumed that the processing of form can be explicit or conscious only as or after the surface property such as color is filled in. In conjunction with extant psychophysical findings, these developments point to interesting distinctions between nonconscious and conscious processing of these attributes, specifically in relation to distinguishable temporal dynamics. At nonconscious levels form processing proceeds faster than surface processing, whereas in contrast, at conscious levels form processing proceeds slower than surface processing. I mplications of separate form and surface processing for current and future psychophysical and neuroscientific research, particularly that relating cortical oscillations to conjunctions of surface and form features, and for cognitive science and philosophy of mind and consciousness are discussed

A survey of new towns about metropolitan areas with special reference to Montreal.

In this survey of towns examples of them occurring at various periods of time have been selected. As far as possible representative examples have been chosen. In the discussion on the various towns, great detail has been avoided. The reasons for this are that great benefit cannot derive from this alone, and further this type of indexing has been done by many people in great detail previously. The examination of the towns, has been carried out from a subjective point of view. Various criteria such as size, layout and siting are compared

Type-2 Blindsight: Empirical and Philosophical Perspectives

The articles in this special issue on type-2 blindsight all arose from a three-day workshop at University College Dublin in May 2013. The project brought together empirical researchers and philosophers to address the often-overlooked issue of residual awareness in blindsight (type-2 blindsight). The result is a collection of papers that not only present an overview of the current empirical and theoretical work on type-2 blindsight, but also raise important questions for our understanding of methodological and conceptual issues concerning the attribution of awareness in psychophysics, the nature of visual perception and experience, and their underlying mechanisms. In this introduction, we first give a brief overview of the history of research into residual awareness following striate cortical damage and then summarize the contributions to this special issue