Jan E Holly1, Katharine J Harmon. 1. Department of Mathematics, Colby College, 5845 Mayflower Hill, Waterville, ME 04901, USA. jeholly@colby.edu
Abstract
INTRODUCTION: During a coordinated turn, subjects can misperceive tilts. Subjects accelerating in tilting-gondola centrifuges without external visual reference underestimate the roll angle, and underestimate more when backward-facing than when forward-facing. In addition, during centrifuge deceleration, the perception of pitch can include tumble while paradoxically maintaining a fixed perceived pitch angle. The goal of the present research was to test two competing hypotheses: 1) that components of motion are perceived relatively independently and then combined to form a three-dimensional (3-D) perception; and 2) that perception is governed by familiarity of motions as a whole in three dimensions, with components depending more strongly on the overall shape of the motion. METHODS: Published experimental data from existing tilting-gondola centrifuge studies were used. The two hypotheses were implemented formally in computer models, and centrifuge acceleration and deceleration were simulated. RESULTS: The second, whole-motion oriented hypothesis better predicted subjects' perceptions, including the forward-backward asymmetry and the paradoxical tumble upon deceleration. The predominant stimulus at the beginning of the motion and the familiarity of centripetal acceleration were important factors. CONCLUSION: Three-dimensional perception is better predicted by taking into account familiarity with the form of 3-D motion.
INTRODUCTION: During a coordinated turn, subjects can misperceive tilts. Subjects accelerating in tilting-gondola centrifuges without external visual reference underestimate the roll angle, and underestimate more when backward-facing than when forward-facing. In addition, during centrifuge deceleration, the perception of pitch can include tumble while paradoxically maintaining a fixed perceived pitch angle. The goal of the present research was to test two competing hypotheses: 1) that components of motion are perceived relatively independently and then combined to form a three-dimensional (3-D) perception; and 2) that perception is governed by familiarity of motions as a whole in three dimensions, with components depending more strongly on the overall shape of the motion. METHODS: Published experimental data from existing tilting-gondola centrifuge studies were used. The two hypotheses were implemented formally in computer models, and centrifuge acceleration and deceleration were simulated. RESULTS: The second, whole-motion oriented hypothesis better predicted subjects' perceptions, including the forward-backward asymmetry and the paradoxical tumble upon deceleration. The predominant stimulus at the beginning of the motion and the familiarity of centripetal acceleration were important factors. CONCLUSION: Three-dimensional perception is better predicted by taking into account familiarity with the form of 3-D motion.