@article{ref1,
title="What you see is what you step: the horizontal-vertical illusion increases toe clearance in older adults during stair ascent",
journal="Investigative ophthalmology and visual science",
year="2015",
author="Foster, Richard J. and Whitaker, David and Scally, Andrew J. and Buckley, John G. and Elliott, David B.",
volume="56",
number="5",
pages="2950-2957",
abstract="PURPOSE: Falls on stairs are a significant cause of morbidity and mortality in elderly people. A simple safety strategy to avoid tripping on stairs is increasing foot clearance. We determined whether a horizontal-vertical illusion superimposed onto stairs to create an illusory perceived increase in stair-riser height would increase stair ascent foot clearance in older participants. <br><br>METHODS: Preliminary experiments determined the optimum parameters for the horizontal-vertical illusion. Fourteen older adults (mean age ± 1 SD, 68.5 ± 7.4 years) ascended a three-step staircase with the optimized version of the horizontal-vertical illusion (spatial frequency: 12 cycles per stair riser) positioned either on the bottom or top stair only, or on the bottom and top stair simultaneously. These were compared to a control condition, which had a plain stair riser with edge highlighters positioned flush with each stair-tread edge. Foot clearance and measures of postural stability were compared across conditions. <br><br>RESULTS: The optimized illusion on the bottom and top stair led to a significant increase in foot clearance over the respective stair edge, compared to the control condition. There were no significant decreases in postural stability. <br><br>CONCLUSIONS: An optimized horizontal-vertical visual illusion led to significant increases in foot clearance in older adults when ascending a staircase, but the effects did not destabilize their postural stability. Inclusion of the horizontal-vertical illusion on raised surfaces (e.g., curbs) or the bottom and top stairs of staircases could improve stair ascent safety in older adults.<p /> <p>Language: en</p>",
language="en",
issn="0146-0404",
doi="10.1167/iovs.14-16018",
url="http://dx.doi.org/10.1167/iovs.14-16018"
}