I presented a paper on Out of Body Experiences recently in seminar, and people found it very fascinating. Other people have seemed interested as well. So I’m posting it here for people’s perursal should they wish to see it.
Video Ergo Sum: Manipulating Bodily Self-Consiousness
Lenggenhager, Tadi, Metzinger, Blanke
Science, v317, August 2007
(I did have to explain to people that “Cogito ergo sum” is “I think therefore I am”, and “Video ergo sum” is “I see therefore I am”. Then someone challenged me, saying that the title was superfluous because no one speaks Latin. I retorted that I DO speak Latin, and that it is still the official language of the Vatican, thank you very much. It’s not quite dead yet.)
Out of Body Experience: this is defined as the experience in which a person who is awake sees his or her body from a location outside the physical body. About 10% of people will have one of these during their lifetime.
OBEs can be induced by various things:
1) Near Death Experiences (warning, all the links for some of these are of dubious neutrality) are of course the best known. “I floated up and was gazing down upon myself, and I saw my children fighting over the will…”
2) Stroke: this can cause severe confusion and trauma on the part of the person experiencing it. The best known instances are thoses where the person cannot recognize their own paralyzed limb, and is convinced that it belongs to someone else. It’s really bizarre, actually, Dr. Ramachandran reported (in his book Phantoms in the Brain, which is a really cool read if you’re interested) a case study where a woman suffered a stroke, and thenceforth failed to recognize the right side of her body. She’d be lying there, and he’d ask her about her right arm.
Patient: It’s not mine.
Dr: Who’s is it?
Dr: No, mine’s right here, who’s is it?
Patient: Oh! It’s my brother’s.
Though she could walk fine, and reached for things with her right hand, she failed to recognize it when she saw it. She would only put makeup on the left side of her face, and only do the left side of her hair. If you gave her a plate of food, she’d eat the left half, and wonder why she was still hungry.
3) Sleeping: this can occur in people who suffer from severe insomnia. While you are asleep, you believe yourself to be awake and doing things like taking a shower. You can end up with a big shock when you turn around and see yourself still sleeping in bed. People suffer severe psychological trauma from this. It’s actually happened to me once or twice, and though I got a nasty shock when I saw myself in bed, it just made me realize I was dreaming.
Thomas Edison was famous for taking advantage of this, he solved his own experimental problems in his sleep, by falling asleep sitting up, holding rocks. When he feel asleep, the rocks would drop from his hand into the bucket, waking him up. Doing this over and over again would result in out of body experiences in which he would believe himself to be doing experiments in his sleep.
4) Deep trance: some Buddhist monks are capable of obtaining out of body experiences. I’ve always pictured them doing it while balancing on one foot on top of a 20 foot pole.
5) Audio-visual stimulation or electrical stimulation of brain areas: what the experimenters used here with virtual reality.
6) Chemicals: can be induced by sleep-deprivation resulting from methamphetamine use, as well as use of LSD.
7) Sensory deprivation: the most extreme case of this is people who like BONDAGE, especially this thing called mummification. When they are completely bound up and sensory deprived, they have been known to have out of body experiences.
Types of OBEs:
1) Misattribution: I swear, it’s not mine, or maybe it is.
This can occur following some strokes, a person is unable to recognize their own paralyzed arm or leg as belonging to them, they will adamantly insist that it belongs to someone else and has just been left there. When inducing OBEs in the laboratory, it is easier to convince someone that a body part not belonging to them actually does.
2) Mislocalization: No, I’m not here, I’m actually over there
This is another thing that can be induced in the lab, and this is the state that many people with insomnia find themselves in, they feel themselves getting up and walking around when in fact they are lying in bed. It’s measured here as posterior-anterior drift, the patient will drift toward where they think their body is.
3) Heautoscopy: I can see myself from somewhere else.
A defining area of the OBE, viewing yourself from above, or from behind or in front. Though the media usually represents people looking down at themselves, most commonly people report seeing themselves from behind.
So Out of Body Experiences are when your psychological sense of “self”, and your physical sense of self fail to agree. What is it that defines our sense of physical and mental self?
Our sense of self-consiousness is localized to where we believe our body to be. This means that it includes to where our body extends, as well as to where our body is located in space. Ehrsson et al in 2004, determined that activity in the premotor cortex occurs during the recognition of ownership of a limb, whereas activity in the extrastriate body area and in the temporo-parietal junction is more involved in the sense of being localized to one’s physical body (The temporo-parietal juntion is the little corner, you could call it the angular gyrus, I suppose, where the temporal lobe ends and the parietal lobe begins). Strokes and lesions occurring in the temporo-parietal junction will result in difficulties with agency, self-other distinction, and mental body image, while lesions occurring in the premotor cortex are more likely to result in a misattribution of body-part ownership.
So in the experiment discussed here, the scientists used virtual reality to attempt to achieve misattribution and mistakes in self-localization.
The scientists in this experiment modified something called the rubber hand illusion (RHI). When you stroke a fake hand and the participant’s hand synchronously when you are only able to see the fake hand, it causes you to believe that the fake hand is yours (You can find a good video of it on YouTube). This is a case of misattribution wherein vision and touch will dominate over proprioception. You can do this with a friend. Take their right hand and put it under the table. Then take a fake hand (or someone else’s), and put it on top of the table. Take two paintbrushes, and stroke both the fake hand and the person’s real hand. Make sure you are doing this at the same time. It takes anywhere from 20 seconds to 2 minutes.
We know that the RHI works in about 2/3 of subjects. But that’s only a hand. Is there a way to do this to your whole body?
So what happened here was that the scientists used virtual reality to project an image of the subject’s own body to a position 2m in front of their actual position, so the subject was staring at their own back. They then stroked the subject and the virtual body’s backs, both synchronously, and asynchronously.
They then asked them a bunch of questions:
1) “It seemed as if I were feeling the touch of the pen where I saw the virtual object touched.”
When the subject’s back was stroked in synchrony with that of the virtual body, they reported that they were feeling the touch of the pen where the virtual object was being touched
2) “It seemed as though the touch I felt was caused by the highlighter touching the virtual body”
3) “I felt as though the virtual body were my body”
These results could also be achieved when the virtual body was a FAKE virtual body. They just got the projection of a dummy 2m anterior to their position. So even when the subject saw a dummy that didn’t even look like their body, they still were able to misattribute their senses to the dummy. The significance of the results disappeared when they used a virtual OBJECT, just a block instead of something human shaped.
These changes in misattribution also resulted in changes in self-localization. Following the experiment, if you moved the person, and told them to step back to where they thought they were standing, they drifted toward where the virtual projection had been placed. This would only occur if the subject was stroked in synchrony with the fake body.
BUT, these subjects never reported a feeling of overt disembodiment.
In a similar study published by another lab (Ehrrson, 2007), subjects were tested sitting down, again staring at their own backs, and touched on their chest, and reported the feeling of actually sitting behind themselves, the first instance of a laboratory method promoting an out of body experience.
These are the first instances of studying spatial unity and bodily self-consiousness. The cool thing is that, now that we know that we can induce out of body experiences in this way, we can then put people into an MRI or other imaging system to find out what brain activity (we already have a clue as to brain areas) are causing these experiences to happen, and use that knowledge to help people who may be stuck outside their own bodies following traumatic experiences or strokes.
Lenggenhager, B., Tadi, T., Metzinger, T., Blanke, O. (2007). Video Ergo Sum: Manipulating Bodily Self-Consciousness. Science, 317(5841), 1096-1099. DOI: 10.1126/science.1143439
Filed under: Uncategorized