Abstract
Hari and Jousmaki (1996) found that motor activity is initiated more efficiently in response to stimuli located on the responding hand as opposed to near the hand. In previous research, we have found a similar preference for stimuli located on controllable virtual limbs, and concluded that control over a virtual limb is crucial for the incorporation of that limb into body space (Short & Ward, in prep). However, it is well established in the rubber hand illusion that control is not necessary for incorporation, so we report here three experiments investigating the role of visuo-tactile feedback as a mediating factor in the preference for stimuli located on the body. The aim of these studies was to determine whether the experience of visuo-tactile sensation associated with the virtual limbs (‘rubber hand illusion’) could reinstate the preference for stimuli located on a limb not under the control of the participant. Our first experiment found that a rubber hand illusion could be invoked for a virtual limb. Our second and third experiments revealed that prior experience of concurrent visual and tactile feedback appeared to reinstate the bias for stimuli located on non-controllable virtual hands. We discuss these findings in relationship to current theories of personal space and body schema, and suggest that, since it is often the case that sensory feedback is only experienced from an object that is under control (such as the physical body), sensory feedback from a virtual limb (even illusory sensory feedback, as in the current experiments) may lead to the assumption that the limb is likely to be under control, irrespective of actual evidence of command over the object.
Fay Short is funded by the Economic and Social Research Council (ESRC, UK). This work was funded in part by a grant to RW from the ESRC (grant 223651).