(A) A master-slave robotic system was used to allow
participants to move their arms forward and receive tactile feedback on the
back. The feedback was administrated synchronously or asynchronously
(500 ms delay) with the movement, and with our without force feedback at
the participants' fingertip.
(B) Participants reported higher illusory self touch, and showed a larger drift in self-location towards the virtual back in the synchronous compared to the asynchronous condition; drift was also larger in the condition with (versus without) somatosensory force feedback to the participants' fingertip (C). The condition in which five subjects spontaneously reported a FoP is indicated with an arrow.