Action and perception in the rubber hand illusion.

Voluntary motor control over artificial hands has been shown to provoke a subjective incorporation of the artificial limb into body representations. However, in most studies projected or mirrored images of own hands were presented as 'artificial' body parts. Using the paradigm of the rubber hand illusion (RHI), we assessed the impact of tactile sensations and voluntary movements with respect to an unambiguously body-extraneous, artificial hand. In addition to phenomenal self-reports and pointing movements towards the own hand, we introduced a new procedure for perceptual judgements enabling the assessment of proprioceptive drift and judgement reliability regarding perceived hand location. RHI effects were comparable for tactile sensations and voluntary movements, but characteristic discrepancies were found for pointing movements. They were differently affected by the induction methods, and RHI effects were uncorrelated between both methods. These observations shed new light on inconsistent results concerning RHI effects on motor responses.