15:00 - 16:30
Submission 227
Does Motor Hysteresis Apply to Full-Body Posture Planning?
Posterwall-20
Presented by: Christoph Schütz
Christoph Schütz
Faculty of Psychology and Sports Science, Bielefeld University, Germany
Center for Cognitive Interaction Technology, Bielefeld University, Germany
In predictable tasks, such as opening drawers in ordered sequences, individuals persist in prior postures, indicating a reuse of prior motor plans to reduce planning costs (Rosenbaum et al., 2007). This posture hysteresis so far has only been demonstrated for arm movements. The present study examined whether hysteresis constitutes a general planning principle that extends to full-body movements. Twenty-four participants (age 23.5 ± 3.7 (SD) years, 12 male) performed a full-body hysteresis task. On each trial, they walked 5m from a start to a target position. Midway, a horizontal bar served as an obstacle at one of 11 heights. Participants decided whether to step over or duck under the bar. Bar height was varied in ordered sequences (ascending/descending) to induce hysteresis, and decisions were recorded as the dependent variable. A generalised linear mixed model (logit link) was applied to the decisions, with ‘bar height’ and ‘order’ (ascending/descending) as fixed effects. Significant main effects emerged for ‘bar height’, z = +11.830, p < .001, odds ratio (OR) = 4.648*10 7, and ‘order’, z = –2.007, p = .045, OR = 0.476. Participants stepped over lower bars and ducked under higher ones. The point-of-change differed between orders: bar height 6.9 for ascending vs. 7.1 for descending sequences. The shift direction indicated anticipatory rather than persistent postural adjustments. Thus, we were unable to demonstrate persistence as a planning principle for full-body movements, possibly due to the high mechanical costs involved, which tend to reduce the hysteresis effect (Schütz and Schack, 2013).