Callaghan et al., Why Don’t We Know Where Our Fingers Are? A Large-Scale ..., Haptics Symposium 2024
Channel: IEEE Haptics Symposium
Date: 2024-04-05

#haptics #haptics2024
https://www.hapticssymposium.org/
Finger proprioception is important for human-machine interaction but surprisingly inaccurate. To understand this inaccuracy, we designed a finger proprioception experiment using low-cost mechatronics parts that was integrated into a remote laboratory course, obtaining finger proprioceptive accuracy estimates from 109 students. Students held a servomotor shaft with the fingers of one hand as it moved in a random trajectory composed of submovements and tried to reproduce each template by rotating a potentiometer with the other hand, either during or following the displayed movement. Although template and replayed movements were highly correlated (average R2 = 0.67), reproduction error was large for simultaneous replay (20  deg), and even larger for delayed replay (30 deg). This implicates both real-time and memory-based processes as sources of error. We also found that participants overestimated the speed of slow movements, and underestimated the speed of fast ones. Error variability increased at higher speeds. Based these findings, we propose that we don’t know where our fingers are because 1) the accuracy of proprioceptive memory decays rapidly; and 2) finger localization relies on integrating sensed velocity, but sensed velocity is biased and noisy.  #haptics #haptics2024 #proprioception