From: What You See Is What You Step: The Horizontal–Vertical Illusion Increases Toe Clearance in Older Adults During Stair Ascent Invest. Ophthalmol. Vis. Sci.. 2015;56(5):2950-2957. doi:10.1167/iovs.14-16018 Figure Legend: Box and whisker plot of vertical toe clearance data for each staircase appearance condition and for each stair (bottom, middle, top). Key: 1, control condition with horizontal high-contrast edge highlighter on tread edge only; 2, illusion on top and bottom stairs; 3, illusion on bottom stair only; 4, illusion on top stair only. Date of download: 10/18/2017 The Association for Research in Vision and Ophthalmology Copyright © 2017. All rights reserved.