Reliability in Focus: Trust, Agency, Ownership, and Gaze Behaviour in a VR Prosthesis Simulator

Psychological factors such as ownership, agency, and trust are critical to the acceptance and effective use of prosthetic devices, yet their relationship to control reliability remains underexplored. We investigated how induced delays and artificial malfunctions influence these factors during prosthesis simulator use in a fully immersive virtual reality environment. A Pasta Box Task was implemented in Unity with MuJoCo physics simulation, using surface electromyography myocontrol and integrated eye tracking to measure subjective and visuomotor responses. Thirty non-disabled participants completed six within-participant conditions crossing two control delay and three artificial malfunction levels. Validated questionnaires assessed ownership, agency, and trust, while gaze metrics quantified fixation percent, target-locking strategy, and eye arrival and leaving latencies. Both delay and malfunction significantly reduced psychometric scores, with artificial malfunctions exerting the largest overall effect, while delay particularly diminished agency. Artificial malfunctions also increased fixations on the prosthesis and altered gaze strategies, suggesting compensatory behavior. Delay primarily affected eye-arrival latency and the number of fixations, whereas artificial malfunctions influenced target-locking strategy and eye-leaving latency, indicating distinct visuomotor adaptations to each reliability factor. Weak but significant correlations emerged between gaze behavior and psychometric measures. The results of the experiment highlight the value of immersive, physics-accurate virtual reality as an early-stage platform for the controlled evaluation of myocontrol and prosthesis behavior and for capturing relevant psychometric and visuomotor indicators relevant to user-centered design.