SEDL / STP / STP1345-EB / STP12353S

Vision—An Essential Factor for Safety in Skiing: Perception, Reaction, and Motion Control Aspects

Senner, V
Mechanical engineer and sports scientist, BASiS-Institute, TUEV Product Service, Munich,

Jendrusch, G
Biologist and sport scientist, assistant chairman of sports medicine department, Ruhr University Bochum, Bochum,

Schaff, P
Medical doctor, and division manager, TUEV Product Service, Munich,

Heck, H
Professor and head of Sports Medicine Department, Ruhr University Bochum, Bochum,

Pages: 12    Published: Jan 1999

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Abstract

Observation and perception errors in combination with lack of attention explain the majority of all falls in skiing. This associates vision and vision deficiencies with safety aspects in skiing. The purpose of this study was to determine the effect of reduced visual acuity on the reaction time of a skier in safety-critical skiing situations.

For this purpose, field experiments were conducted in the 1995/96 winter season. The subjects had to pass over a prepared ledge in the terrain and react to simulated obstacles, which were partly blocking the course. All experiments were video recorded; in total more than 220 trials were conducted. We tested three different types of obstacles: ice patches, a standing skier, and a skier just starting to move. Two experimental conditions were examined, normal visual acuity and a reduced visual acuity. The acuity reduction to 20% of normal was achieved by the use of special goggles. From the videotape, the subjects' time for an evasive action was determined and statistically analyzed.

No significant change of the reaction time with reduced visual acuity could be seen for the bigger obstacles i.e., the standing skier and the moving skier. However, with the simulated ice patches, the increase of the reaction time was significant (p = 0.01) with an average increase of 35%. From the obtained results it is concluded that skiers not wearing their corrective lenses may feel safer than they really are. They can perceive larger, stationary, or moving objects, however they might not be aware of the risk from low-contrast obstacles.