Neurophilosophy

2 more days of sensory deprivation

total_isolation_sensory_deprivation.bmp

Last Tuesday’s episode of Horizon, called Total Isolation, is available for viewing and download at the BBC iPlayer website for the next 2 days. In the 50-minute documentary, Professor Ian Robbins, a trauma psychologist at the University of Surrey who specializes in supporting torture victims, reconstructs a highly controversial study first performed in the 1950s.

The new study involved six subjects who volunteered to experience 48 hours of complete sensory deprivation. The volunteers first performed a battery of tests designed to assess various cognitive functions, such as visual memory, verbal fluency and suggestibility. They were then deprived of all sensory stimuli for 2 days, and observed throughout, before performing the same tests again.

It is well known, from numerous animal experiments, that sensory stimuli are essential for proper brain development to occur. However, there are very few studies of the effects of sensory deprivation on humans, largely because of the highly unethical nature of the experiments involved.

The original study was led by the preeminent psychologist Donald Hebb (1904-1985). It was funded by the U.S. military, in order to determine the effects on American and Canadian prisoners held under such conditions during the Korean War, but was quickly aborted because it was considered to be cruel. 

The Horizon episode includes footage of Hebb discussing the results of the original study, and expressing his surprise at the dramatic effects of even short periods of sensory deprivation. These effects can be seen clearly in the volunteers involved in the reconstruction. They become anxious very quickly, and some of them experience visual and auditory hallucinations.

From the animal work, it is clear that such deprivation leads to weakening of the synapses within the brain’ s sensory systems. This almost certainly occurs in humans too – as the second set of tests shows, the volunteers’ general ability to process information was significantly reduced.

These effects are, of course, reversible, as the volunteers were deprived of stimulation for just 48 hours. But the findings have obvious implications for the tens of thouseands of prisoners around the world who are held under such conditions for much longer periods of time – this could lead not just to weakening of synapses, but to large-scale loss of connections throughtout the brain.

The volunteers in the new study were also found to be more suggestible after than before the sensory deprivation, which raises serious doubts about the reliability of information obtained from prisoners who have been kept in solitary confinement. Robbins discusses all these issues in the programme, and this article in The Times contains more information.

Comments

  1. #1 antropos
    January 28, 2008

    This clip is only viewable from within the UK. The BBC uses Geo-IP to determine your ISP…

    Do you know of any other location we can have a look at this episode?

  2. #2 Mo
    January 28, 2008

    Try using a proxy server.

  3. #3 Caledonian
    January 28, 2008

    and expressing his surprise at the dramatic effects of even short periods of sensory deprivation

    The man is an idiot. Experiments of this type were done decades ago, and the results are well-known. There’s no reason to do them all over again – except to provide a show for the ignorant public.

  4. #4 ~C4Chaos
    January 29, 2008

    cool! thanks for the info. too bad i can’t access the video too. will wait for it to appear on Google Videos ;)

    in the meantime, i wonder how this sensory deprivation study could be correlated with brain waves (i.e. other states of awareness).

    you said: “It is well known, from numerous animal experiments, that sensory stimuli are essential for proper brain development to occur.”

    however, one of the initial stages of some schools of meditation (i.e. Tibetan Buddhism) is sensory deprivation (that’s why monks seek caves and ashrams to minimize sensory stimuli). in meditation literature sensory deprivation is essential in order to *advance* in other meditation techniques. some scientific research done on meditation suggests that advanced meditators exhibit more brain plasticity. so it seems that there are techniques of sensory deprivation that actually helps brain development (i.e. plasticity). the keyword here is *technique* as opposed to just plain sensory deprivation.

    here’s a case in point.

    http://www.youtube.com/watch?v=LFFMtq5g8N4

    in this video, Ken Wilber (a philosopher and advanced meditator) plays around with his brain waves (and eventually stops its activity). based on your understanding of neuroscience, was there an instance where Wilber went to a state of total sensory deprivation (i.e. losing sense of touch, smell, taste, hearing, seeing, during delta waves)?

    i’d appreciate your take on this.

    thanks for your time.

    ~C

  5. #5 Flyboy
    January 29, 2008

    C4Chaos: Excellent point! I’ve always considered this to be a great example of why introspection is important to take into consideration — put two people in sense dep; one of them could go mad while the other creeps toward enlightenment.

  6. #6 JR
    January 30, 2008

    C –
    Interesting post. I wonder if the difference here is intent. That is, with meditation one must focus to reduce their awareness of their senses, and the moment that is lost (accidentally or intentionally) they are back. With sensory deprivation however it doesn’t matter if you open your eyes or keep them shut or half lidded – there’s still nothing there regardless of what you do. You’re not creating it, you’re trapped in it.
    - J

  7. #7 morgaine
    January 30, 2008

    As brilliant as Wilber is as a philosopher he is simply not up to date on brain wave science. The video where he “stops” his brain waves is appalling- he is giving out inaccurate information regarding the basics of normal brain wave function…particularly in regard to delta waves. People have active waking delta all the time and it is not usually indicative of a tumor OR even high meditative advancement. It IS associated with an unconscious scanning of the environment or personal radar, so to speak. This is so especially for people who have experienced childhood abuse or PTSD. Also, people who are highly empathic, or work in the helping professions have more waking delta than average. Delta can also be hyper-active when people don’t have well defined personal boundaries. ANd yes, its active in deep dreamless sleep.

    Still, one cannot understand the complete implications of a persons delta waves or any brain wave pattern.. without delving into the subjective content of their mind…( once ruling out physical pathology as causation or contribution toward any pattern)

    His inaccurate statements re delta reinforce my intense doubt about his claims regarding his mastery of his brain waves.

    I am a certified neurofeedback practitioner, I apprenticed under the woman (Anna Wise) who developed the Mind Mirror EEG,(the very one he used..though I use a later model, also a real time full spectrum brain wave analyzer). After 30 years of intensive research, Ms Wise is considered one of the worlds leading authorities on EEG and consciousness/ peak performance states. She is certainly the expert on this brand of EEG that he uses! If you want to know brain waves as they relate to meditative states.. check HER out, as well the other highly regarded researchers in the field.. not Wilber. He also did not even mention what he had the attenuator set to. I can easily hook up to the Mind Mirror and adjust the attenuator such that it APPEARS there is no brain wave activity other than delta. It makes no sense that he would have flat lined everything but delta given the fact that as far as I know its never been seen by any of the advanced meditater’s or monks MS Wise studied in over 30 years. Very specious

    What does matter..and has been very helpful for many people, is to learn how to enter at will into a peak performance state rather than wait for it to arrive. I am referring to ‘the zone’ as it were- this is characterized by little beta, strong active alpha and theta with or without delta. This has been dubbed the Awakened Mind. It is essentially a working meditation. It is the barin wave state seen during moments of inspiration and optimal performance in any field. Train your brain waves to go there more often, THAT will assist you in life… being able to operate solely in delta..why?

  8. #8 ~C4Chaos
    February 2, 2008

    morgaine,

    thanks for your detailed response. just to let you know, this video is old. i think it’s more than 10 years already. that’s why when you listen to Wilber he kept saying that more research should be done on this matter and it’s just his own personal experiment to illustrate the different states of meditation (depending on the technique). he’s basically saying that people who are advanced practitioner of meditation are able to manipulate their brain waves at will and could enter different states of consciousness. the brain wave machine could show some kind of a “fingerprint” of different states of consciousness. the terminology he used are based on Buddhist concepts (e.g. nirvilkalpa samadhi). most of these states are different from the regular “peak” or zone experience because they occur in a non-waking consciousness.

    in any case, thanks for the heads up on Ms. Wise. will look her up. i think it would be great to have Wilber repeating this experiment with her so she could add her own expertise on the matter.

    ~C

  9. #9 Rodney Chalfant
    August 24, 2010

    psychologist Donald Hebb (1904-1985) is guilty of . . .

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