Adaptive force control in grasping as a function of level of developmental disability.

Background  The adaptation to the task demands of grasping (grip mode and object mass) was investigated as a function of level of developmental disability. Methods  Subjects grasped objects of different grip widths and masses that were instrumented to record grip forces. Results  Proportionally, fewer participants from the profound compared with moderate and severe disability groups were able to complete the prehensile tasks. Nevertheless, all participants who completed the task showed adaptive grasping behaviour in terms of level and variability of force produced. There was higher absolute and relative force variability in low mass tasks that was enhanced with greater level of developmental disability. Conclusions  The findings show task relevant adaptive grasping control with inhibition of force output at very-low-force conditions being the primary performance deficit of the profound disability group as a function of level of developmental disability.