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Marc S Tibber, Dean R Melmoth, Simon Grant, Michael J. Morgan; Eye movements and visuospatial perceptual extrapolations compete for common resources. Journal of Vision 2009;9(8):397. doi: 10.1167/9.8.397.
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© ARVO (1962-2015); The Authors (2016-present)
Although there is evidence for multiple spatial maps in the brain, including in posterior parietal cortex, it is not clear to what extent visuospatial perceptual and motor tasks rely on common neural representations and attentional resources. Using a dual-task interference paradigm we tested the hypothesis that shared resources are competed for during eye movements and perceptual extrapolations that require access to simultaneously presented visuospatial information. Observers undertook judgements of stimulus collinearity (perceptual extrapolation) using a pointer and Gabor patch and performed saccades to a peripheral dot target alone and in combination whilst their eye movements were recorded. In addition, observers performed a non-spatial control task (contrast discrimination) in order to distinguish between the general effects of dividing attention and the more specific effects of inter-task interference. Whilst contrast discrimination performance was unaffected by eye movements perceptual extrapolation acuity was significantly reduced. In addition, although significant effects were not seen at the group level, trends both in group and individual data suggest that perceptual extrapolations may disrupt saccadic profiles to a greater extent than do judgements of relative contrast. These data show that eye movements and perceptual extrapolations share common neural / attentional resources that are largely independent of those involved in encoding / comparing stimulus contrast. Future studies are planned to determine whether tasks requiring attention to other spatial attributes of a stimulus (e.g. spatial frequency or size) exhibit a similar interference effect, or whether in fact visuospatial extrapolation is unique in its association with eye movement / motor resources.
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