Alternating images of congruent and incongruent movement creates the illusion of agency.

We report a novel illusion whereby people perceive both congruent and incongruent hand motions as a united, single, and continuous motion of one's own hand (i.e. a sense of agency). This arises when individuals watch congruent and incongruent hand motions alternately from a first person perspective. Despite an individual knowing that s/he is not performing the motion, this illusion still can arise. Although a sense of agency might require congruency between predicted and actual movements, united motion is incongruent with predicted movement because the motion contains oscillating movement which results from switching hand movement images. This illusion offers new insights into the integration mechanism of predicted and observed movements on agency judgment. We investigated this illusion from a subjective experience point of view and from a motion response point of view.

Development of a BCI master switch based on single-trial detection of contingent negative variation related potentials.

To control the startup/shutdown of a conventional brain-computer interface (BCI) that is always running for daily use, we proposed and developed a new BCI system called a BCI master switch. We designed it with on/off switching functions by detecting the contingent negative variation (CNV)--related potentials. We chose CNV to improve the single-trial discrimination of user intentions to switch because CNV had a high signal-to-noise ratio and needed high concentration for its elicitation. We also applied a support vector machine (SVM) to improve the single-trial detection of CNV-related potentials. As the best parameters of SVM were estimated and applied, the offline evaluation's best performance achieved a CNV detection rate of 99.3% for the intention to switch and 2.1% for the intention not to switch. Remarkably, this performance was achieved from single-trial detection, imaginary response of user's intention without physical reaction, and the data from only one recording electrode. These results suggest that our proposed BCI system might work as a master switch by single-trial detection.