The addition of stripes (a version of the 'horizontal-vertical illusion') increases foot clearance when crossing low-height obstacles.
Trips over obstacles are one of the main causes of falling in older adults, with vision playing an important role in successful obstacle negotiation. We determined whether a horizontal-vertical illusion, superimposed onto low-height obstacles to create a perceived increase in obstacle height, increased foot clearances during obstacle negotiation thus reducing the likelihood of tripping. Eleven adults (mean ± 1 SD: age 27.3 ± 5.1 years) negotiated obstacles of varying heights (3, 5, 7 cm) with four different appearance conditions; two were obstacles with a horizontal-vertical illusion (vertical stripes of different thickness) superimposed on the front, one was a plain obstacle and the fourth a plain obstacle with a horizontal black line painted on the top edge. Foot clearance parameters were compared across conditions. Both illusions led to a significant increase in foot clearance when crossing the obstacle, compared to the plain condition, irrespective of obstacle height. Superimposing a horizontal-vertical illusion onto low-height obstacles can increase foot clearance, and its use on the floor section of a double-glazing door frame for example may reduce the incidence of tripping in the home. Practitioner Summary: Low-height obstacles such as the floor section of a double-glazing door frame are potential tripping hazards. In a gait lab-based study we found that a horizontal-vertical illusion superimposed onto low-height obstacles led to significantly higher foot clearances; indicating their potential as a useful safety measure.
a SHAPE Research Group, School of Science and Technology , Nottingham Trent University , Nottingham , UK.
Richard J
RJ
Foster
b Division of Medical Engineering , School of Engineering, University of Bradford , Bradford , UK.
John G
JG
Buckley
c Cardiff School of Optometry and Vision Sciences , Cardiff University , Cardiff , UK.
David
D
Whitaker
d Bradford School of Optometry and Vision Science , University of Bradford , Bradford , UK.
David B
DB
Elliott
D000058:Accidental Falls / Q000517:prevention & control*; D000328:Adult; D005430:Floors and Floorcoverings; D005528:Foot / Q000502:physiology; D005684:Gait / Q000502:physiology*; D006801:Humans; D014796:Visual Perception; D055815:Young Adult
Tripping; door-frame; horizontal-vertical illusion; obstacle crossing; toe clearance