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Saccade-stepping interactions revise the motor plan for obstacle avoidance.
Richard P Di Fabio1, John F Greany, Cris Zampieri
1Department of Physical Medicine & Rehabilitation, University of Minnesota School of Medicine, Minneapolis, MN 55455, USA. difab001@umn.edu
Journal of Motor Behavior
|November 11, 2003
Summary
Older adults exhibit slower obstacle avoidance responses compared to younger adults, with prolonged gaze fixation and saccade-footlift latencies. Optical flow disruptions are crucial for adapting to changes in obstacle contact time.
Area of Science:
- Human movement science
- Neuroscience
- Gerontology
Background:
- Gait adjustments are essential for obstacle negotiation.
- Age-related changes can impact motor control and visual processing during locomotion.
Purpose of the Study:
- To investigate age-related differences in obstacle avoidance using a stimulus-response compatibility paradigm.
- To examine the role of visual cues and optical flow in adapting to altered time-to-contact with obstacles.
Main Methods:
- Participants (young and older adults) performed a gait task towards a foam obstacle.
- A limb-selection cue initiated saccadic eye movements to guide foot placement.
- Saccade-step and saccade-footlift latencies were measured, along with gaze fixation duration.
Main Results:
- Both age groups exhibited similar saccade-step latencies after the cue.
- Older adults showed significantly longer saccade-trailing-footlift latencies and gaze fixation times.
- Gaze direction shifted from footfall targets to forward-looking as the obstacle was approached.
Conclusions:
- Older adults demonstrate age-related deficits in obstacle avoidance, particularly in the later stages of the gait cycle.
- Optical flow disruptions are critical for successful adaptation to unexpected changes in obstacle contact time.
- Gaze control strategies differ between young and older adults during obstacle negotiation.