Fig 1.
Sensor glove and robotic hand without protective gloves.
Fig 2.
(a) Experiment 1: The right hand of the participant is placed inside a box and equipped with a sensor glove. The box and the participant’s upper body are covered by a black cloth. The participant is instructed to grasp and release the ball. (b) Experiment 2: A ball device is attached to the robotic hand system. When the ball is at its zero position (maximally away from the open robotic hand), it is hidden under the visual cover. While the robotic hand is closing, the ball moves towards the palm in a circular trajectory (dashed red arrow).
Table 1.
Questionnaire items divided into the factors ‘Ownership’ (items 1–5), ‘Location’ (items 6 and 7), and ‘Agency’ (items 8 and 9).
Table 2.
Means and standard deviations (SD) of the proprioceptive drift and questionnaire data (averaged across all items and split into its subcategories) in Experiment 1.
Fig 3.
Box-plots for the means and standard deviations of the proprioceptive drift in the fully synchronous motor (MF) and tactile feedback (TF) condition (MFs/TFs), compared to the compound score, reflecting the linear combination of effects caused by synchronous (s) and asynchronous (a) feedback.
Table 3.
Post hoc comparisons for the proprioceptive drift in Experiment 1.
All p-values are Bonferroni-corrected.
Table 4.
Means and standard deviations (SD) of the proprioceptive drift and questionnaire data (averaged across all items) in Experiment 2.
Fig 4.
Proprioceptive drift under conditions of motor (MF) and tactile feedback (TF) with their levels synchronous (s), asynchronous (a), and no feedback (n).
Table 5.
Post-hoc paired t-tests (two-tailed) for the proprioceptive drift in Experiment 2 (detailed testing of synchronous (s) and asynchronous (a) conditions).
All p-values are Bonferroni-corrected.
Table 6.
Post-hoc paired t-tests (two-tailed) for the proprioceptive drift in Experiment 2 (detailed testing of combined synchronous (s) and no-feedback (n) conditions).
All p-values are Bonferroni-corrected.
Fig 5.
Box-plots for the means and standard deviations of the proprioceptive drift in the fully synchronous motor (MF) and tactile feedback (TF) condition (MFs/TFs), compared to a) the compound score s/a, reflecting the linear combination of effects caused by synchronous (s) and asynchronous (a) feedback, and to b) the compound score s/n, reflecting the linear combination of effects caused by unimodal feedback. Bayes factors (BF): * BF10 < 3; **BF10 >100.