Robert D. McIntosh

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When we reach out to pick something up, our arm is directed to the target by visuomotor networks in the cortical dorsal stream. However, our reach trajectories are influenced also by nontarget objects, which might be construed as potential obstacles. We tested two patients with bilateral dorsal-stream (parietal lesions, both of whom were impaired at(More)
In everyday life our reaching behaviour has to be guided not only by the location and properties of the target object, but also by the presence of potential obstacles in the workspace. Recent evidence from neglect and optic ataxia patients has suggested that this automatic obstacle avoidance is mediated by the dorsal, rather than the ventral, stream of(More)
The perception-action model proposes that vision-for-perception and vision-for-action are based on anatomically distinct and functionally independent streams within the visual cortex. This idea can account for diverse experimental findings, and has been hugely influential over the past two decades. The model itself comprises a set of core contrasts between(More)
The remote distractor effect is a robust finding whereby a saccade to a lateralised visual target is delayed by the simultaneous, or near simultaneous, onset of a distractor in the opposite hemifield. Saccadic inhibition is a more recently discovered phenomenon whereby a transient change to the scene during a visual task induces a depression in saccadic(More)
When asked to compare two lateralized shapes for horizontal size, neglect patients often indicate the left stimulus to be smaller. Gainotti and Tiacci (1971) hypothesized that this phenomenon might be related to a rightward bias in the patients' gaze. This study aimed to assess the relation between this size underestimation and oculomotor asymmetries. Eye(More)
Visuomotor adaptation to rightward displacing optical prisms is known to induce temporary improvements in the symptoms of left visual neglect. We report a 74 year-old woman with severe and chronic neglect of nine months duration, who underwent three weekly sessions of prism adaptation. Substantial improvements were obtained on tests of visual neglect(More)
The perception/action model is the dominant account of the primary division of labour in the human visual pathway. Integral to this model is the idea that goal-directed actions are guided spatially by bottom-up vision, independent of perceptual recognition and top-down object knowledge. We question this idea by showing that the expected size of familiar(More)
Distractors presented contralateral to a visual target inhibit the generation of saccades within a precise temporal window (Buonocore & McIntosh, 2008; Reingold & Stampe, 2002; Walker, Kentridge, & Findlay, 1995). The greatest 'dip' of saccadic inhibition typically occurs at about 90 ms after distractor onset, with a subsequent recovery period showing an(More)
Optic ataxia, following dorsal stream lesions, is characterised by impaired visuomotor guidance. Recent studies have found concurrent perceptual deficits, but it is unclear whether these are functionally related to the visuomotor symptoms. We studied the ability of a well-documented patient (IG) with bilateral optic ataxia to react to sudden target jumps by(More)
Optic ataxic patients have deficits in the visual control of manual reaching and grasping. It has been established previously that these deficits in target-directed behaviour improve following a delay in response. Recently it has been demonstrated that optic ataxic patients also have deficits in taking potential obstacles into account during reaching. The(More)