Referred sensations elicited by video-mediated mirroring of hands.

Humans readily perceive ownership of a limb even when it is artificially induced as in the case of using a mirror reflection. However, mirror reflections are very constrained perceptions which do not allow transformations and varied contexts as often occurs in real life. The extent to which perceived limb ownership occurs with video-mediated manipulations is not known, particularly given the perception would no longer be a precise copy (reflection) of a person's own limb. The present study directly compared referred sensations of the limbs with the use of a mirror reflection to those obtained with a new video-mediated setup to assess perceived ownership. Manipulations that could not be performed with a standard mirror reflection, such as reversal of the spatial positions of the limbs, were also investigated to examine how far the perceived ownership effects could be pushed. Across a series of experiments, data on the quality, intensity and location of referred sensations were collected and analyzed together with measures of hand ownership and participants' experience of the two setups. Results reveal that participants felt referred sensations in both the optical and the video-mediated setup, and that video-mediated manipulations of hand-position reversals produced equal to stronger effects of ownership compared with the mirror reflection. These findings open up new possibilities for scientific experimentation and therapy that are discussed in the paper.