Hysteresis in posture selection in preschool children

In a repetitive, sequential task, we tend to reuse our former motor plans to save cognitive planning cost. This reuse results in a persistence in the former posture, termed motor hysteresis. In the current study, we asked if this planning principle for cost minimization would already be present in early childhood development. To this end, we asked 4- to 6-year-old preschool children to open a column of slotted drawers in an ascending and in a descending sequence. As the dependent variable, we documented whether children used an over- or underhand grasp for each drawer. A majority of children switched from the default overhand to an underhand grasp for the lower drawers. The point-of-change shifted as a function of sequence: the children persisted in their initial, underhand grasp in the ascending and in an overhand grasp in the descending sequence. The results indicate that preschool children can inhibit the default grasp posture to adapt to the biomechanical requirements of a task and that hysteresis as a planning principle is either innate or already well developed at an early age.