Visual Versus Kinesthetic Motor Imagery for BCI Control of Robotic Arms (Mercury 2.0)

Motor Imagery (MI), the mental execution of an action, is widely applied as a control modality for electroencephalography (EEG) based Brain-Computer Interfaces (BCIs). Different approaches to MI have been implemented, namely visual observation (VMI) or kinesthetic rehearsal (KMI) of movements. Although differences in brain activity during VMI or KMI have been studied, no investigation with regards to their suitability for BCI applications has been made. The choice of MI approach could affect individual performance during BCI control, especially for off-the-shelf BCI systems, where ease of use and fast reliable results is the target. Whether for healthy individuals or clinical applications, if such systems are expected to reach consumer maturity, best practices for their use should be investigated. We designed a study to compare VMI and KMI as control modalities of an off-the-shelf EEG-BCI system. 30 healthy individuals (18 male, 12 female) participated in the study, operating two house-developed robotic arms (Mercury 2.0) using an Emotiv EPOC EEG-BCI. They were asked to use first VMI and then KMI to achieve BCI control and we compared the training and success rates. In our study, KMI achieved higher skill percentages during imagery training but VMI achieved higher success rates during BCI control of both robotic arms. Nonetheless, observed differences did not exceed significance thresholds. Individual differences could play a major role in MI performance and should be taken into account when choosing which modality to train for the use of a BCI system.