Recently, Lenggenhager et al. (2007) studied bodily awareness for one's entire body (ownership) using multisensory (visual-somatosensory) conflict and virtual reality technology, showing that ownership for body parts and the entire body rely on similar multisensory mechanisms. In the present setup we combined this line of research with research protocols on agency in order to investigate motor contributions to the bodily awareness of the entire body (agency).

We asked 9 subjects to walk towards 4 different target positions while their body movements were tracked (via optical tracking). Movements were mapped to a virtual body and played back, in real-time, on a projection screen. either spatially deviated or not. The body movement and position of the virtual character were deviated systematically from the participants’ movements using different spatial offsets. Motor performance and motor awareness were measured.

Results show that subjects are unaware of angular biases of ~10 deg despite participants' motor behaviour (significantly deviated walking paths in the direction opposite to the spatial offset; p<0.001). Our paradigm makes it possible to quantify when humans become consciously aware of sensorimotor movement conflicts for the position of their entire body. These data show that despite precise motor control, motor awareness is very limited for full body actions.