Highlights
- •In familiar settings, feedforward visual control is similar in young/older adults.
- •Older adults exhibit increased dependence on vision for postural stability.
- •LTC and TTC are correlated when crossing obstacles ≤ 10 cm high regardless of age.
Abstract
In
order to safely avoid obstacles, humans must rely on visual information
regarding the position and shape of the object obtained in advance. The
present study aimed to reveal the duration of obstacle visibility
necessary for appropriate visuomotor control during obstacle avoidance
in healthy older adults. Participants included 13 healthy young women
(mean age: 21.5 ± 1.4 years) and 15 healthy older women (mean age:
68.5 ± 3.5 years) who were instructed to cross over an obstacle along a
pressure-sensitive pathway at a self-selected pace while wearing liquid
crystal shutter goggles. Participants were evaluated during three visual
occlusion conditions: (i) full visibility, (ii) occlusion at T-1 step
(T: time of obstacle crossing), and (iii) occlusion at T-2 steps. Toe
clearances of both the lead and trail limb (LTC and TTC) were
calculated. LTC in the occlusion at T-2 steps condition was
significantly greater than that in other conditions. Furthermore, a
significant correlation was observed between LTC and TTC in both groups,
regardless of the condition or obstacle height. In the older adult
group alone, step width in the occlusion at T-2 steps condition
increased relative to that in full visibility conditions. The results of
the present study suggest that there is no difference in the
characteristics of visuomotor control for appropriate obstacle crossing
based on age. However, older adults may exhibit increased dependence on
visual information for postural stability; they may also need an
increased step width when lacking information regarding their positional
relationship to obstacles.
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