Monday, September 6, 2010

Out of body, out of mind

   Three years ago Dr. Henrik Ehrsson, a researcher at University College London (UCL) in the UK, crafted an experiment designed to make a healthy person feel as though they were having an "out-of-body experience."
   I'd like to recap the experiment and the implications, as reported by Science Daily in an article dated Aug. 24, 2007, as I think we have a ways to go before we really understand this phenomenon.
   The video, Laboratory-Induced Out-of-Body Experiences, is informative. You can watch it at the end of this article,
   When I first read about Ehrsson's experiment in 2007, it seemed so simple that it struck me as funny. Sitting in a chair, the participant is fitted with a live, head-mounted video display with separate displays for each eye in order to give the full 3D stereoscopic effect. The displays are then hooked up to a camera about 6 feet behind the person and the camera focused on the back of their head. Standing beside the participant within eyesight, the researcher then touches the participant's actual chest with a plastic rod while at the same time (pretending) to touch the chest of the illusory one by the camera.
   Visually, the person sees their illusory body getting gently poked in one location, but feels it getting poked in another, disrupting the mind's normal sensation of where it senses the "self" to be located.
  But Ehrsson took the experiment even further by measuring the perspiration of the participant's skin while pretending to threaten the phantom persona of sorts behind the participant's actual body. True to the illusion, their bodies showed a strong reaction to the simulated threat as thought it were real.
   You can see a picture of the experiment and read the ScienceDaily story here. The full text of Ehrrson's conclusions are available online by subscription at Science Mag.  You can also read about Ehrsson's experiment in an extensive out-of-body page on Wikipedia. See: Out of Body
   "The invention of this illusion is important because it reveals the basic mechanism that produces the feeling of being inside the physical body," Ehrsson says in the article. "This represents a significant advance because the experience of one's own body as the centre of awareness is a fundamental aspect of self-consciousness."
   According to Ehrsson, the experiment was one of the first to induce such experiences in healthy individuals.
   "OBEs have been reported in clinical conditions where brain function is compromised, such as stroke, epilepsy and drug abuse. They have also been reported in association with traumatic experiences such as car accidents. Around one in ten people claim to have had an OBE at some time in their lives," he said.
   Further experiments using the technique were reported in a Dec. 1, 2008 story by the New York Times entitled, "Standing in Someone Else’s Shoes, Almost for Real."  For more about Ehrsson's current research, visit: Ehrsson's Lab.