An experimental and computational approach to the dynamic body boundary problem

In this paper, we propose an experimental and computational model to challenge the dynamic body boundary problem, as seen in the rubber hands illusion and phantom limbs. Our strategy examines an agent‟s “attention shift”. A computational model (Iizuka & Ikegami, 2005) was used to explore how a body and sensor can be made inseparable. A model agent was required to determine the number of vanes on a windmill by touching the windmill blindly with a stick. By adding an additional windmill to the first one, we investigated the agent‟s shift of attention, i.e. the agent could either determine the vanes on the first windmill, or the second windmill by using the first one as a tool. In other words, an agent‟s body image can shift from its arm tip to the boundary between the first and second windmill. We then introduced an experiment with a real windmill model to test the hypothesis shown by the theoretical model. Subjects were tasked with determining the number of vanes on the second windmill. We found that sensory-motor correlations between their actions and perceptions of the movement of the windmills were helpful for the attention shift but still not enough to extend their body