In a second test, Ehrsson connected sensors to the skin to measure electrical conductance, which indicates emotional response.

He then allowed them to watch a hammer swing down to a point below the camera, as though it were going to hurt an unseen portion of the virtual body.

Their skin conductance registered emotional responses including fear, indicating they sensed their selves had left their physical bodies and moved to the virtual bodies where the hammer was swung.

The research has applications in neuroscience and also potentially in industrial applications involving virtual reality, he said.

Meanwhile, a team led by Olaf Blanke, a professor at the Laboratory of Cognitive Neuroscience at Ecole Polytechnique Federale in Lausanne, Switzerland, conducted a similar experiment using virtual reality goggles.

In these tests, the subjects could see a three-dimensional representation of their body, the body of a dummy, or a simple object directly in front of them. The subject then saw the back of the image being stroked with a paintbrush, either in or out of sync with someone stroking his own back.

Then the participants were blindfolded and backed up, and then asked to return to their original position.

Those whose backs were stroked synchronously with the virtual image of themselves or the human dummy consistently overshot their position in the direction of the image; but subjects who saw no virtual image or a simple object did not.

The study aimed at determining how senses play a role in self consciousness, Blanke said.

Ehrsson's research was funded by the Wellcome Trust, the Presence: Research Encompassing Sensory Enhancement, Neuroscience, Cerebral-Computer Interfaces and Applications Project, the Human Frontier Science Program, Swedish Medical Research Council and the Swedish Foundation for Strategic Research. Blanke's work was funded by the Cojito Foundation, Foundation de Familie Sandoz, the Foundation Odier and the Swiss National Science Foundation.