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Norbert Boeddeker, Simon Jetzschke, Marc Ernst; Persistent personal biases in walking. Journal of Vision 2015;15(12):1325. doi: https://doi.org/10.1167/15.12.1325.
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© ARVO (1962-2015); The Authors (2016-present)
Locomotion along a given path in the absence of vision and audition is known to be inaccurate. Here we ask about the nature of these inaccuracies. To this end, we analyzed the performance of participants in three walking experiments involving straight and angle-walking tasks. In the first experiment eight blindfolded participants were guided along paths of different lengths and asked to turn to a target location by an angle of ±90° in a sports hall (size: 25x45m). We found significant biases in turn angles, i.e. systematic deviations from the correct angle that were characteristic of certain participants, whereas varying path length had weak effects on turn accuracy and precision. To check whether this idiosyncrasy was persistent over time and present in another type of walking task, we performed a second experiment several weeks after the first. Here, the same participants were guided to walk turns with varying amplitude. We then asked them to judge whether they had walked an angle larger or smaller than 90° in a two-alternative forced-choice (2AFC) paradigm. Very surprisingly, the personal bias was highly correlated between the two experiments indicating that the sense of direction can be persistently and individually biased in the absence of external directional cues. In a third experiment the participants where asked to walk straight on slanted and level surfaces. Here, we again found persistent directional biases in most participants. The direction of surface inclination did not significantly influence these individual biases. We found systematic angular biases in several walking tasks that were persistent over weeks. The biases reported here for healthy participants are most likely counterbalanced during normal daily-life by using visual and auditory cues for spatial orientation.
Meeting abstract presented at VSS 2015
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