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Jeanine Stefanucci, Michael Geuss; Perception of the height of a barrier is scaled to the body. Journal of Vision 2010;10(7):85. doi: 10.1167/10.7.85.
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© ARVO (1962-2015); The Authors (2016-present)
When walking through or judging passage through an aperture, people allow for a margin of safety (Warren & Whang, 1987). Furthermore, this margin is preserved when the body is widened by holding a large object (Wagman & Taylor, 2005). In a series of five experiments, we question whether actions and judgments toward a different dimension, height, are also scaled to the body. In Experiment 1, participants allowed for a 3% margin of safety when walking under a horizontal barrier. In Experiment 2, participants were made taller by wearing a helmet and strapping blocks under their shoes. For both manipulations, participants were conservative in their walking behavior (e.g., allowing for a larger margin of safety). In the final 3 experiments, participants judged whether they could walk under barriers viewed from a static position and visually matched the height of the barrier to a horizontally projected line. In Experiments 3 and 4, participants who viewed the barriers while wearing the blocks or the helmet required a similar margin of safety for passage under as participants whose height was not altered. Visually matched estimates were also no different when wearing the blocks as compared to not. However, participants wearing a helmet visually matched the height to be shorter than participants who did not wear a helmet. In the final experiment, experienced helmet wearers (ROTC members) showed no difference in visually matched estimates of height compared to those not wearing a helmet. Overall, the results suggest that people allow for a margin of safety when walking under a barrier, which is preserved when judging from a static position and when height is altered. However, estimates of the height may differ based on the type of judgment being made and experience with alterations to height.
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