Action strategies when avoiding two vertical obstacles

Abstract

Individuals inherently walk towards open spaces and avoid colliding with obstacles to reduce the risk of injury¹. Research has demonstrated that young adults use body-scaled information to alter their movements when walking through confined spaces^2,3. Young adults consistently require a safety margin greater than or equal to 1.3 times their shoulder width (termed Critical Point) in order to pass through an aperture without changing their actions². It is unknown as to whether individuals maintained similar body-scaled strategies when controlling their actions in situations where they are not obligated to walk through a confined space. The current study was designed to test the action strategies of young adults during an unconfined goal-directed locomotor task. The unconfined space consisted of a vertically oriented goal at the end of a 10m pathway and two vertically oriented obstacles placed half way (i.e. 5m from start) along the pathway on either side of the pathway's midline. The obstacles created an aperture that varied between 0.6-1.8 times each individuals shoulder width, but and allowed individuals to choose one of three possible pathways (middle, or around either obstacle). Individuals were instructed to walk to the goal at a natural pace and in a manner they felt was appropriate for success. No direct instructions were provided as to how to avoid the obstacles. Preliminary results indicate that young adults (N=12) chose to walk around the obstacles when the aperture was less than 1.4 times their shoulder widths (?²_{(7 )} = 58, p<0.001). This avoidance strategy was initiated when participants were, on average, 3.52m from the obstacles. Although there was inconsistency in side of avoidance across participants (8 avoided to the right, 3 avoided to the left), each participant consistently avoided the obstacles towards the same side, regardless of the aperture width. References [1] Gibson, J.J. (1979). The ecological approach to visual perception. Houghton Mifflin, Boston: NY. [2] Warren, W.H. and Whang, S. (1989). Visual guidance of walking through apertures: Body- scaled information for affordances. Journal of Experimental Psychology, 13: 371- 83. [3] Wilmut, K. and Barnett, A. (2010). Locomotor adjustments when navigating through apertures. HumanMovement Science. 29: 289-98. [4] Wilmut, K. and Barnett, A. (2011). Locomotor behavior of children while navigating through apertures. Experimental Brain Research, 210: 185- 94. [5] Hackney, A.L., & Cinelli, M.E. (2011). Action strategies of older adults when walking through apertures. Gait and Posture. 33 [4]: 733-36.