August 2012
Volume 12, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2012
Do the two cerebral hemispheres act as independent tracking mechanisms?
Author Affiliations
  • Scott McLean
    University of Delaware
  • Sarah Wells
    University of Delaware
  • Elizabeth Postell
    University of Delaware
  • Matt Doran
    University of Delaware
  • James Hoffman
    University of Delaware
Journal of Vision August 2012, Vol.12, 554. doi:10.1167/12.9.554
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      Scott McLean, Sarah Wells, Elizabeth Postell, Matt Doran, James Hoffman; Do the two cerebral hemispheres act as independent tracking mechanisms?. Journal of Vision 2012;12(9):554. doi: 10.1167/12.9.554.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Information in each visual field is initially processed in visual areas located in the contralateral hemisphere. This segregation of information between the two hemispheres quickly gives way to integrated representations that result from the rapid sharing of information across the corpus callosum. An exception to this integration process is provided by split brain patients who have had their corpus callosum severed to control the spread of epileptic seizures from one hemisphere to the other. Remarkably, this operation results in superior performance of split-brain patients compared to controls on several visual tasks. For example, patients are able to search for targets in the two visual fields simultaneously resulting in a doubling of search speed compared to controls. In contrast, presenting bilateral displays to normal observers generally results in an advantage relative to unilateral presentation but one that is considerably less than the doubling of performance seen in split-brain patients. An exception to this rule was reported by Alvarez, & Cavanagh (2005) who found that bilateral presentation in a multiple object tracking task (MOT) allowed observers to track twice as many objects relative to unilateral presentation. They suggested that the two cerebral hemispheres acted as independent object tracking systems in MOT. We attempted to replicate this result in four different experiments but in all cases, we found a bilateral advantage that fell well short of the doubling of performance predicted by independent tracking systems. It appears that MOT, like other tasks such as visual search, and visual short-term memory, shows a bilateral advantage that falls short of hemispheric independence.

Meeting abstract presented at VSS 2012

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