Gaze behavior and visuospatial attention in compensatory stepping responses.
Published: 2006
Language: eng
Number of pages: 153
ISBN-13: 9780494219812
Description: Compensatory stepping reactions were evoked in healthy young and older adults by sudden, unpredictable movement of a large platform. Visual behavior was examined when modulating the response to clear a high frontal obstacle, stepping to a target, or both, and switches in attention were inferred by performance on a secondary visuomotor pursuit task. Results suggest that a 'remembered' spatial map of the surrounding environment is predominately used to guide rapid stepping reactions in young and older adults.It has been well established that postural control requires cognitive resources; however, the attentional demand of triggered balance responses executed amid environmental constraints is unknown. This thesis sought to determine: (1) how and when visuospatial information of the environment is obtained; (2) whether this is related to switches of attention; (3) the associated attentional demand of accommodating compensatory stepping to environmental constraints; (4) how this changes with healthy ageing.Dual-task and balance-only trials were compared to further examine visual and attentional behavior. The frequency of downward gaze deviations increased without the secondary task, but a substantial portion of trials still did not include downward gaze shifts. The findings further indicate that remembered spatial information is commonly used to guide rapid perturbation-evoked stepping movements, even in the absence of competing demands for visual attention.These results indicate that young and older adults are able to guide compensatory stepping reactions using remembered spatial information under both static and more dynamic and unpredictable conditions, and that attention switching is not related to efforts to acquire online visual information.In the final study, a dynamic environment was employed to further challenge the capacity to 'remember' environmental features. Subjects stood surrounded by four obstacles that moved intermittently in an unpredictable sequence. Visual scanning and fixation of the obstacles occurred prior to, but never after, perturbation onset in both young and older adults. At step initiation, both young and older adults gaze was directed ahead of any obstacles and eventual swing-foot landing site, and both groups were able to avoid obstacle contact on the first step.
Notes: Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0129.

Thesis (Ph.D.)--University of Toronto, 2006.

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