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A comparison study of motor-imagery-based brain-computer interfaces with allocentric and egocentric visual feedback in virtual reality

  • Author(s): Davis, Dylan Lee
  • Advisor(s): Jung, Tzyy-Ping;
  • Cauwenberghs, Gert
  • et al.

Motor Imagery based Brain Computer Interfaces (MI BCI) have been studied as applications for the improving rehabilitation and recovery, as well as augmenting existing function. The feedback in these MI BCI systems is traditionally presented in an egocentric reference frame, with allocentric reference frame stimuli restricted to supplementary stimuli or Mirror Therapy. This study proposes to assess whether the use of an allocentric reference frame for stimulus presentation is comparable to egocentric stimuli, by evaluating both allocentric and egocentric stimuli presented in a dynamic Virtual Reality (VR) environment during the execution of left-handed and right-handed grasping motor imagery. When assessed in terms of inter-rater agreeability and precision, there were comparable results between the allocentric and egocentric reference frame tasks. The Cohen’s kappa score of the classified activity was not significantly different between the two reference frames. Additionally, when the data was trained on the first VR Dynamic trial and evaluated cross-reference frame and session, the precision and Cohen Kappa score increased compared to the 2D calibration derived classifier. The results suggest that Allocentric reference frames can serve as a viable MI BCI framework, outside of mirror therapy, and should be explored further in environments that invoke VR Body Ownership Transference (BOT).

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