Tracking the Sense of Agency in BCI Applications

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This thesis paper presents an experiment where participants were given the task to make a virtual hand on a screen execute one of two gestures, cued via audio instructions. Subjects were led to believe that they controlled the virtual hand through a brain-computer interface with a technique known as motor imagery. However, the actual hand movement was pre-programmed, making every Sense of Agency the participants reported illusory. Timing between the instruction cue and hand movement was manipulated between two blocks. After each manipulation a questionnaire was filled out, measuring the subject’s Sense of Agency over the virtual hand. During the blocks an electroencephalogram (EEG) was measured. The results of this experiment were compared to the results of research by Wegner, Sparrow, and Winerman on a similar non-BCI task. The Sense of Agency rating were found to be significantly higher when compared to the non-BCI experiment. In addition this thesis holds a section on the predictive powers of several models for the Sense of Agency and concludes with the suggestion to opt for a more refined model that would actually allow to predict not only the presence of the Sense of Agency but the strength of it. Keywords: authorship processing, brain-computer interface, comparator model, Sense of Agency, Sense of Self, Helping Hands
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