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Brett Fajen, Sean Barton, Jonathan Matthis; Visual information for the control of walking over complex terrain. Journal of Vision 2015;15(12):1321. doi: 10.1167/15.12.1321.
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© ARVO (1962-2015); The Authors (2016-present)
Which regions of the ground surface do humans need to see to control walking over complex terrain? Previously, we offered an answer to this question rooted in the biomechanics of walking: To efficiently exploit their inverted-pendulum-like structure, walkers should use information about potential target footholds for an upcoming step during the last part of the preceding step. That is, the last part of each step is the critical phase for the visual control of the upcoming step. The aim of the present study was to determine the nature of the visual information used during this critical control phase. To efficiently exploit their biomechanical structure, walkers must initialize each step with a pushoff force from the trailing foot that is properly tailored to the position of the next target relative to the previous target. This leads to the hypothesis that walkers rely on information about the relative position of pairs of consecutive targets. To test this hypothesis, we instructed subjects to walk along a path of irregularly spaced target footholds (small circular patches of light projected onto the floor) while their movements were tracked by a motion capture system. On some trials, the visibility of a subset of targets was manipulated such that they were only visible for a brief period. The duration of the period of visibility varied such that consecutive targets were simultaneously visible in some conditions (leaving relative position information intact) but not others. We found no significant differences in stepping accuracy between conditions in which relative position information was available and a control condition in which all targets were always visible. However, stepping accuracy degraded in conditions in which relative position information was unavailable. We conclude that walkers rely on relative position information and that such information facilitates energetically efficient walking over complex terrain.
Meeting abstract presented at VSS 2015
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