Prospective gait changes as a function of shifting perceptions of slipperiness: effects of visual and somatosensory cues

Abstract

Forty participants, ages 18–45 years, rated perceived slipperiness before and after walking on five different floors under three different surface conditions. The before-ratings were taken as a proxy for visual cues to slipperiness, while after-ratings were taken as a proxy for somatosensory feedback received while walking on the surface. Before and after ratings of slipperiness were used to predict gait parameters, as a function of trial, during repeated walking. Effects of after-ratings of slipperiness were observed beginning on the second trial, and continued through the fifth trial, while effects of before-ratings of slipperiness were most apparent on the first trial. When perceived slipperiness increased (or decreased) from before to after walking on the surface, gait became more (or less) protective across trials. It is concluded that both visual cues, as well as somatosensory feedback, are used in the prospective control of gait.

Practitioner Summary: Effects of visual and somatosensory cues to slipperiness on gait were disentangled using floor surfaces varying in the slipperiness suggested by those cues. Visually based ratings of slipperiness predicted gait parameters on earlier trials, while somatosensory-based ratings predicted gait parameters on subsequent trials. Flooring design should provide reliable information regarding slipperiness.

Keywords:

• Gait
• somatosensation
• vision
• prospective control

Acknowledgements

The authors would like to thank Niall O’Brien, Amanda Rivard, Navrag Singh and Greg Schultz for their assistance in data collection; Chris Brunette and Angela Garabet for assistance in COF measurement; Jacob Banks for his assistance in data processing; Rick Holihan, Edmund Correa and Peter Teare for design and construction of the moving walkway; YoonSun Choi for assistance in data analysis and for comments on an earlier version of the manuscript; and Peg Rothwell for assistance in recruitment and in manuscript preparation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. There is some indication in the data that the tribometer might be underestimating ACOF. It is a known that the slipmeter used in the current experiment has excessive squeeze-film effect (see Chang et al. 2001). However, it is a well-accepted and established slipmeter.

2. Ideally, gender should be included as a variable. However, there were insufficient data to consider this variable in addition to the primary variables of interest. The data should not be biased, however, since the numbers of males and females were similar and each person served as their own control (i.e. it was a within-subject design).

3. While Figure 3 shows an apparent ‘overshoot’ for the 2–2 vs. 2–4 and the 3–3 vs. 3–4 lines (see trial 3 vs. trial 5), post-hoc analyses indicated that none of these differences were significant.