June 2007
Volume 7, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2007
Inefficient eye movements correlate with difficulties in perceiving global stimuli in Balint's syndrome
Author Affiliations
  • Kirsten A. Dalrymple
    Department of Psychology, University of British Columbia
  • Walter F. Bischof
    Department of Computing Science, University of Alberta
  • David Cameron
    Department of Psychology, University of British Columbia
  • Jason J. S. Barton
    Department of Psychology, University of British Columbia, Department of Visual Sciences and Ophthalmology, University of British Columbia, and Department of Neurology, University of British Columbia
  • Alan Kingstone
    Department of Psychology, University of British Columbia
Journal of Vision June 2007, Vol.7, 23. doi:10.1167/7.9.23
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Kirsten A. Dalrymple, Walter F. Bischof, David Cameron, Jason J. S. Barton, Alan Kingstone; Inefficient eye movements correlate with difficulties in perceiving global stimuli in Balint's syndrome. Journal of Vision 2007;7(9):23. doi: 10.1167/7.9.23.

      Download citation file:


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

      ×
  • Supplements
Abstract

Patients with Balint's syndrome often report Local portions of visual scenes, but not the Global percept. Other researchers have reported that the eye movements of Balint's patients while they identified Local and Global levels of hierarchical letters do not differ between successful and unsuccessful trials. We replicated and extended this experiment by recording eye movements of a Balint's patient (SL) and of controls while they identified, on separate trials, letters at Global or Local levels of hierarchical stimuli. Controls were highly accurate for Global and Local trials and made only a few fixations, most of which landed at centre-screen. SL took longer and made more fixations per second than controls, with fewer fixations to centre-screen. She had normal accuracy for identifying Local elements, but poor accuracy during Global trials. SL's performance differed between Global and Local tasks, with Global trials showing longer reaction times, fewer fixations per second, and a lower proportion of fixations overlapping with the letter stimulus. When comparing SL's successful to unsuccessful Global trials, while there were no significant differences in the distribution of fixations in different regions of the screen, SL did have shorter reaction times and a higher proportion of fixations overlapping with the letter stimulus per second during successful trials than during unsuccessful trials. We conclude that SL demonstrates a need to explore Global and Local letters more than controls, reflecting her difficulty with information accrual during fixations, consistent with her attentional difficulties. The more difficult Global task is associated with a reduced fixation rate and less fixation-stimulus overlap. Fixation-stimulus overlap is further decreased in Global trials on which she made errors. These features suggest that any preserved Global perception in SL may be dependent on local fixations of the stimulus, consistent with a spatial constriction of attention.

Dalrymple, K. A. Bischof, W. F. Cameron, D. Barton, J. J. S. Kingstone, A. (2007). Inefficient eye movements correlate with difficulties in perceiving global stimuli in Balint's syndrome [Abstract]. Journal of Vision, 7(9):23, 23a, http://journalofvision.org/7/9/23/, doi:10.1167/7.9.23. [CrossRef] [PubMed]
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×