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On the covert orienting of visual attention task (COVAT), responses to targets appearing at the location indicated by a non-predictive spatial cue are faster than responses to targets appearing at uncued locations when stimulus onset asynchrony (SOA) is less than approximately 200 ms. For longer SOAs, this pattern reverses and RTs to targets appearing at(More)
Many studies have demonstrated that prism adaptation can reduce several symptoms of visual neglect: a disorder in which patients fail to respond to information in contralesional space. The dominant framework to explain these effects proposes that prisms influence higher order visuospatial processes by acting on brain circuits that control spatial attention(More)
The line bisection task is used as a bedside test of spatial neglect patients who typically bisect lines to the right of true centre. To disambiguate the contribution of perceptual from motor biases in bisection, previous research has used the landmark task in which participants determine whether a transection mark is left or right of centre. One recent(More)
The visually guided reaching of two patients with bilateral optic ataxia was explored in two experiments. In Experiment 1 simple delayed pointing was compared with immediate pointing. In the immediate pointing task both variable and constant errors increased with target eccentricity. In contrast to the performance of control subjects and contrary to their(More)
Blindsight broadly refers to the paradoxical neurological condition where patients with a visual field defect due to a cortical lesion nevertheless demonstrate implicit residual visual sensitivity within their field cut. The aim of this paper is twofold. First, through a selective review of the blindsight literature we propose a new taxonomy for the(More)
The superior hemiretina in primates and humans has a greater density of ganglion cells than the inferior hemiretina, suggesting a bias towards processing information in the lower visual field (loVF). In primates, this over-representation of the loVF is also evident at the level of striate and extrastriate cortex. This is particularly true in some of the(More)
The dramatic improvements of neglect symptoms after prism adaptation (PA) have been interpreted as evidence that PA reorganizes higher levels of spatial representation. Here the authors demonstrate that while the exploratory eye movements of a patient with neglect were clearly shifted toward the left after PA, he still showed no awareness for the left side(More)
Currently, there is debate regarding both the spatial and temporal relationship between facilitation and inhibition of return (IOR) components of attention, as observed on the covert orienting of visual attention task (COVAT). These issues were addressed in a series of experiments where the spatial and temporal relationships between cue and target were(More)
Earlier research has suggested that optic ataxia, a deficit in reaching in peripheral vision, can be isolated from Balint's syndrome as it is primarily a visuomotor disorder, independent of perceptual or attentional deficits. Yet almost no research has examined the attentional abilities of these patients. We examined peripheral visual attention in two(More)
Visually guided prehension is controlled by a specialized visuomotor system in the posterior parietal cortex. It is not clear how this system responds to visual stimuli that lack three-dimensional (3D) structure, such as two-dimensional (2D) images of objects. We asked a neurological patient with visual-form agnosia (patient D.F.) to grasp 3D objects and 2D(More)