Fig 1.
Subjects were equipped with an EEG cap, a VR headset and headphones. A total of 17 markers (LEDs) were strapped on their body to track the head, shoulders, elbows and hands.
Fig 2.
Illustration of the experiment design.
A:The experiment consisted of six phases; i) calibration, ii) explanation, iii) training, iv) reaching task, v) experimental task and some breaks. The explanation phase consisted of four trials to illustrate each experimental condition. Subjects performed eight more trials during the training phase to ensure that they understood and performed the task correctly. B: The experimental task is the succession of 2 steps. During the active induction step, two conditions can be presented to the subject, either Embodied or Non-Embodied with the avatar. In the monitoring step, two conditions can occur to either produce a Disruption (the right virtual hand rotates by itself) or No Disruption (nothing happens). In the figures, the grey arm is avatar’s arm movement (as seen by the subject in VR) and the red arm corresponds to participants’ physical arm movement (not shown in VR, shown here for illustration purposes). Following the 2 steps, participant’s subjective rating of body ownership is gathered.
Fig 3.
Embodiment questionnaire results for all conditions.
Participants rated their sense of embodiment by answering to “I felt as if the virtual body was my body” after each trial in a visual analog scale (VAS) ranging from “Not at all” (0) to “Very Much” (100). Each dot represents an individual participant.*QFDR < 0.05, **QFDR < 0.01, ***QFDR < 0.001.
Fig 4.
ErrPs elicited by BiE at event onset (t = 0).
Three components were identified: ERN is defined as the first negative deflection occurring between 100 and 200ms, Pe is the first positive deflection occurring between 200 and 300 ms and N400 is the negative deflection occurring between 400 and 600ms. A: Topographical distribution in the four conditions during the time window of the significant effect for ERN, Pe and N400. B: Time-locked average time-courses at parietal (Pz), central (Cz), and front-central (FCz) electrodes. The vertical black line corresponds to t = 0s when the hand animation starts. The gray background areas represent the time windows in which two-way ANOVA showed a main effect between conditions(QFDR < 0.01). C: Mean amplitudes at each time window identified (in gray) *QFDR < 0.05, **QFDR < 0.01, ***QFDR < 0.001.
Table 1.
Results of post-hoc analysis for ERN at the electrode Pz, Cz and FCz.
Table 2.
Results of the post-hoc analysis for Pe at the electrode Pz, Cz and FCz.
Table 3.
Results of the post-hoc analysis for N400 at the electrode Cz and FCz.