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

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

Space, Body and Montage in the Hybrid Installation Work of William Kentridge

This article explores the recent animated film installations and operatic stage direction of William Kentridge to conceptualise emerging trends in installation work, artists’ cinema and hybrid forms of the moving image. Kentridge opens new horizons for the articulation of the moving image with architectural space, reimagining the nature of film. Through a study of Kentridge’s installation, I Am Not Me, The Horse Is Not Mine’, his staging of the Shostakovich opera, The Nose, and his installation work at documenta 13, the article explores how Kentridge mobilises the full potential of the material encounter with the filmic image in new forms of dynamic montage. Drawing on understandings of the tactile, sensory, kinaesthetic engagement with the image, the article examines how Kentridge incorporates the three-dimensional spatiality and materiality of an exhibition/architectural space into the filmic. Through this enquiry, the article considers the broader significance of Kentridge’s work for reconceptualising cinematic experience

Color contrast processing in human striate cortex

Color constancy refers to the unchanging nature of the perceived color of an object despite considerable variation in the wavelength composition of the light illuminating it. The color contrasts between objects and their backgrounds play a crucial role in color constancy. We tested a patient whose right striate cortex had been removed and demonstrated that he made no use of color contrast in judging color appearance but instead made judgments based simply on wavelength comparison. This was shown by presenting pairs of colored stimuli against a background color that gradually changed across space. When presented with such displays, both normal observers and those with cerebral achromatopsia (cortical color blindness) judge the color appearance of such stimuli on the basis of the chromatic contrast the stimuli make against their background rather than on the physical wavelengths of the light emitted from them. However, our patient made no such use of color contrast but, instead, made color discriminations simply on the basis of wavelength composition. This is consistent with recent findings from monkey electrophysiology that identify cells in early cortical visual areas that signal local contrast and so contribute to the likely mechanism for achieving color constancy

Evidence for longevity differences between left handed and right handed men: an archival study of cricketers.

STUDY OBJECTIVE--The aim was to examine the relationship between handedness and longevity. DESIGN--This was an archival (retrospective) survey of a cohort of adult men who had played 'first-class cricket'. SETTING--The United Kingdom PARTICIPANTS--The subjects consisted of all of the deceased players included in an encyclopedia of 'first-class cricket' whose bowling hand had been recorded (n = 3165). The study also considered a further 2314 players, born before 1951 but still alive at the time the book was published (1984). MEASUREMENTS AND MAIN RESULTS--Using the bowling hand as an indicator of handedness it was possible to compare the lifespans of 2580 right handed men and 585 left handed men. The average life spans of the two groups differed by 25 months (right = 65.62, left = 63.52), a highly significant difference (p = 0.006). An examination of cause of death (where noted) strongly indicated that the left handed men were more likely to die prematurely in accidents or in warfare. As a consequence, when these unnatural deaths were removed from the sample the longevity difference between the right handers and left handers was considerably reduced. There was no evidence that these results related to any longitudinal change in the proportion of right handers to left handers across the time course of the sample. CONCLUSION--The study found clear evidence that left handedness was associated with a decrease in longevity among a cohort of adult, athletic men. A major factor responsible for this result seemed to be a differential likelihood of accidental death or death during warfare