Faculty Research and Publications

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Browsing Faculty Research and Publications by Author "Bryant, Devon C."

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    Assessing visuospatial abilities in healthy aging: a novel visuometor task
    (Frontiers Media, 2016) de Bruin Nutley, Natalie; Bryant, Devon C.; MacLean, Jessica N.; Gonzalez, Claudia L. R.
    This study examined the efficacy of a novel reaching-and-grasping task in determining visuospatial abilities across adulthood. The task required male and female young (18–25 years) and older adults (60–82 years) to replicate a series of complex models by locating and retrieving the appropriate building blocks from an array. The task allows visuospatial complexity to be manipulated independently from the visuomotor demands. Mental rotation and spatial visualization abilities were assessed. The results showed that the time taken to complete the tasks increased with increased mental rotation complexity. Patterns of hand use were also influenced by the complexity of the models being constructed with right hand use being greater for the less complex models. In addition, although older adults consistently performed the visuomotor tasks slower than the younger adults, their performance was comparable when expressed as the percent change in task demands. This is suggestive that spatial abilities are preserved in older adults. Given the ecologically validity, the described task is an excellent candidate for investigating: (1) developmental; (2) sex-based; and (3) pathology-based differences in spatial abilities in the visuomotor domain.
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    "Left neglected," but only in far space: spatial biases in healthy participants revealed in a visually guided grasping task
    (Frontiers Media, 2014) de Bruin Nutley, Natalie; Bryant, Devon C.; Gonzalez, Claudia L. R.
    Hemispatial neglect is a common outcome of stroke that is characterized by the inability to orient toward, and attend to stimuli in contralesional space. It is established that hemispatial neglect has a perceptual component, however, the presence and severity of motor impairments is controversial. Establishing the nature of space use and spatial biases during visually guided actions amongst healthy individuals is critical to understanding the presence of visuomotor deficits in patients with neglect. Accordingly, three experiments were conducted to investigate the effect of object spatial location on patterns of grasping. Experiment 1 required right-handed participants to reach and grasp for blocks in order to construct 3D models.The blocks were scattered on a tabletop divided into equal size quadrants: left near, left far, right near, and right far. Identical sets of building blockswere available in each quadrant. Space use was dynamic, with participants initially grasping blocks from right near space and tending to “neglect” left far space until the final stages of the task. Experiment 2 repeated the protocol with left-handed participants. Remarkably, left-handed participants displayed a similar pattern of space use to right-handed participants. In Experiment 3 eye movements were examined to investigate whether “neglect” for grasping in left far reachable space had its origins in attentional biases. It was found that patterns of eye movements mirrored patterns of reach-to-grasp movements.We conclude that there are spatial biases during visually guided grasping, specifically, a tendency to neglect left far reachable space, and that this “neglect” is attentional in origin.The results raise the possibility that visuomotor impairments reported among patients with right hemisphere lesions when working in contralesional space may result in part from this inherent tendency to “neglect” left far space irrespective of the presence of unilateral visuospatial neglect.