Discrete Tactile Feedback Based on Weber's Law Enhances Prosthetic Hand Approaching Performance Under Divided Visual Attention.

In multiple vision-demanding tasks, accurately controlling a prosthetic hand to approach a target object is particularly challenging for amputees, as visual attention diverted by other tasks forces them to rely heavily on peripheral vision. This study aims to initially validate that functionally effective sensory feedback can enhance the control of prosthetic hands during object approach under divided visual attention. To quantify prosthesis users' ability to approach and manipulate objects using central and peripheral vision in real-life scenarios, we conducted two experimental tasks-APPROACHING and PINCH-under two visual feedback modes: full-vision and partial-vision. During the approaching process, we compared four feedback conditions: no supplementary sensory feedback (PURE), traditional continuous feedback (CONT), evenly distributed discrete feedback (ADIS), and a novel discrete strategy based on Weber's law (WDIS) proposed in this study. Task performance was evaluated using metrics such as position error, dispersion, task completion time, and pinch failures, while psychological factors were assessed through a questionnaire. Results show that WDIS enabled more accurate and stable object approach, with shorter task completion times, which leads to better subsequent manipulation performance. This also provides participants with enhanced psychological experiences, including reduced workload and increased intuitiveness. WDIS improved prosthetic control and user experience in the simplified laboratory settings, providing a foundation for real-world applications.