Gaze behavior during adaptive gait
It is well known that vision is a critical aspect of successfully avoiding hazards in the environment. However, it is unknown how visual fixations are related to the ability to avoid tripping on a visible, stationary obstacle. When young adults step over a stationary, visible obstacle in the lab, the foot inadvertently contacts the obstacle in 1-2% of trials (Heijnen, Muir, & Rietdyk, 2012). This provides a protocol to compare how factors such as visual fixations are related to the ability to avoid an obstacle. Young healthy adults (20.6 ± 1.3 yrs) stepped over an obstacle in the walkway for 150 trials. Participants were categorized as: 13 non-trippers (37%), 12 single-trippers (34%), 10 repeated-trippers (29%). Compared to repeated-trippers, non-trippers had a higher percentage of trials with an obstacle fixation (p=0.05), they spent more of the approach phase fixating on the obstacle (p=0.05), and they had a higher frequency of fixations on key features such as the top of the obstacle (p?0.02). These behaviors reflect greater attention to key environmental features, and more opportunity to gather and process visual information. Thus, the non-trippers may have avoided obstacle contact due to superior information regarding obstacle height and position, which in turn improved the visuomotor transformation. Gaze interventions that include more frequent fixations on the obstacle and surrounding walkway can be assessed empirically in future studies, similar to demonstrations that the ‘quiet eye’ technique improves athletic performance (Vickers, 2009).
Rietdyk, Purdue University.
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