Performance of dexterous object manipulation is enhanced by grasp force modulation

Abstract Dexterous manipulation relies on the ability to attain two goals: controlling object position and orientation (pose) and preventing object slip. Although manipulation has been extensively studied, previous work focused on the control of digit forces for slip prevention. Therefore, how digit forces are coordinated to simultaneously prevent slip and control pose remains unknown. We developed a task requiring subjects to lift an object at different grip configurations while preventing it from tilting. We then mathematically decomposed digit forces into manipulation and grasp forces for pose control and slip prevention, respectively. We found that exertion of seemingly excessive grasp force was instrumental in enhancing manipulation performance. This novel phenomenon was more pronounced at the onset of lift than during hold, underscoring anticipatory mechanisms of pose control before feedback is acquired following object lift. Our approach and findings open new research avenues for investigating neural mechanisms underlying dexterous manipulation and clinical applications.