Flotation Tank Courtesy Harmony Yoga & Wellness Center, Tucker, GA 30084

“When one realizes one is asleep, at that moment one is already half-awake.” ― P.D. Ouspensky

In 1951, the composer John Cage entered a anechoic chamber at Harvard University. An anechoic chamber is a specially designed room to stop sound and electromagnetic waves. Needless to say, the room is quiet. One of such rooms in 2005 was designated by the Guinness Book of World Records as the quietest place on Earth. Of course, the room is only quiet as long as nobody is in the room. When Cage entered the room, he heard two sounds. One of them was the sound of his nervous system in operation and the other the sound of his blood circulating. Cage wrote of the experience: “Until I die there will be sounds. And they will continue following my death. One need not fear about the future of music.” (1) The experience inspired his famous composition 4’33” which consists of a pianist doing nothing but opening and closing the lid of the piano to mark the three movements of the piece for four minutes and thirty-three seconds. The music is not what the pianist played (or didn’t play) but the sounds of four minutes and thirty-three seconds.

In 2011, I entered a flotation tank for the first time. I had been interested in flotation tanks for years. I believe I first became aware of them reading something by John Lilly, one of the pioneers in the study of sensory deprivation. The early tanks Lilly worked with were complicated affairs that required breathing apparatus and assistance getting in and out of the them. If you ever have seen the movie Altered States, a movie by Ken Russell from a novel loosely based on John Lilly’s research by Paddy Chayefsky, you have an idea what was involved. The main character in the movie played by William Hurt mixes some psychedelic agents into the experience, as did Lilly, and deconstructs back to some original human form and eventually back to the primordial glop from which the universe was created.

My own experience was somewhat less than that of the movie character and without any additional agents. A modern tank contains water with a large amount of dissolved Epsom salts. You enter through a door without any clothes and lie on your back in the water. You are completely buoyant on your back with the water lapping just around your face and nose out of the water so no breathing apparatus is required. Earplugs keep water out of your ears and also dampened any environmental sound even more. The water is about body temperature. Between the darkness of the tank, the earplugs, and the temperature of the water, most of your sensory input is gone. What you hear is mostly what Cage heard in the anechoic chamber – the sound of blood circulating, your heart, and the sound of your nervous system, which is now free to roam on its own.

Initially there is an adjustment period of finding the best position – hands at side or hands supporting head – then adjustments to the earplugs and assuring yourself that you are not going to sink. Next comes a period where your mind is mostly racing through the typical stuff that occupies our thoughts – what you will be doing later, wondering if you are hungry, feeling the sliminess of the water, and so on. The adjustment period in my experience takes about a half hour to forty-five minutes. My initial sessions were only an hour-long so it was only at the very end of the sessions that I began to get to the next level. My last session was three hours long and, perhaps because of lack of pressure of time, I seemed to get to a deeper level more quickly.

Consciousness seems briefly freed from its physical basis. In the absence of external stimuli or with external stimuli much reduced for an extended period of time, it begins to work in somewhat different manner from normal waking consciousness. Even in Lilly’s early experiments, people left in an isolation tank for many hours eventually begin to hallucinate. They lose sense of time and the distinction between wakefulness and sleep breaks down. This was something I experienced even in the brief three hours I was in the tank. Similar effects can be achieved by providing a neutral or featureless sensory input in place of reduced input. Wolfgang Metzger had people gaze into a featureless field in the 1930’s and measured changes in their electroencephalograms. This is known as the Ganzfield effect. The hallucinations are believed to result from an amplification of noise. Isolation sometimes for months at a time is technique of various yogas. The Dzogchen tradition of Tibetan Buddhism has a practice called the dark retreat during which the student resides in a dark room for an extended period. During this period the practitioner engages in various meditations and visualizes gods, goddesses, and gurus. Some believe that the effects of many hallucinogens are caused by a scrambling of sensory input and the resulting order that the brain itself imposes when the accustomed order is absent. Scientists in Brazil, for example, found while doing brain scans of people taking ayahuasca that the scans of induced visions were the same as scans produced from actual sight.

What seems clear is that even perception, perhaps the simplest component of consciousness, seems to involve active participation of neural system itself In other words, the brain and sensory apparatus are not passive mirrors reflecting the outside so much as they actively molding the outside world. What’s more they seem to be compelled to make order from sensory input. In the absence of input or with featureless input, they create order anyway. Even sensory perception contains a good deal of participatory activity from an organism’s neural structure. In other words, pure perception does not really exist.

So what is this thing we call consciousness? People seem to use the term in different ways and many arguments about it can be traced to usage. Consciousness to some means self-awareness. To others consciousness is awareness or sensual perception perhaps with some ability to act on the perceptions. To others consciousness is closely aligned with intelligence and would include self-awareness and higher thinking abilities.

I think we need to think of these things on a scale from participatory perception, awareness with ability to act, ability to plan and anticipate, self-awareness, and higher capabilities. I think all of these things are involved with consciousness but there seems to be a clear boundary between perception with largely instinctual response and perception combined with a degree of planning and anticipation. It is this latter ability which I am more specifically calling consciousness here.

A considerable philosophical industry has developed arguing whether machines might be intelligent or conscious. While it might be interesting to debate whether non-living entities, such as computer systems, can be conscious, the fact is that there are no such entities in existence that we know of today. Nor is there any guarantee that if such entities were to exist in the future that their consciousness would be in any way equivalent to human or even biological consciousness. So to understand consciousness I think we need to understand how the neurological system and the brain evolved Consciousness, as it actually exists, does have a physical basis but it is basis in biology.

We could begin with the most primitive organisms and examine them for indications of a neurological system. Clearly many very primitive organisms have rudimentary sensing organs Some have argued for intelligence in molds. Others for consciousness in plants, Certainly jellyfish and related species have a diffuse set of organs for detecting light, touch, and chemicals. But none of these organisms have the fundamental parts from which a consciousness as I am using the term could be constructed. They are not on the ancestor path of animal consciousness. There is, however, one very primitive organism that is: worms.

Basic Bilaterian Structure

Worms were among the earliest representatives of the bilateria, the major group of animals possessing bilateral symmetry, that is they have front and back along with an upside and a downside. Jellyfish, for example, are not members of this group because they lack a front and back. The typical worm might be thought of as a digestive tract with mouth and anus on its ends and a primitive brain located near the mouth and neurological cord running the length of the digestive system. The vast majority of what we typically think of as animals are members of this group including ourselves. The hypothetical ancestor of this group is called urbilaterian and was thought to have been worm-like. All bilateria have a mouth and a nervous system and most have an anus. They have sensory apparatus and concentration of neurons near the mouth. Every organism with a complex nervous system is a member of this group.

The same basic body plan found in the worm is found in fish, reptiles, amphibians, mammals, and, of course, humans. We, like the worm, are a digestive tract with a mouth and brain at one end, an anus at the other end, and a neural cord running the length parallel to the digestive tract. The evolutionary path between the worm and ourselves is primarily a path of increasing elaboration on the worm body plan. With vertebrates over 500 million years ago, the neural cord becomes more protected by becoming encased in vertebrae and we have what the origin of what can truly be called a brain. With mammals about 200 million year ago, the brain increases in size and the neocortex develops. Primates about 65 million years ago develop an enlarged cerebral cortex.

Where consciousness is found on this trail could be debated. Consciousness probably did not suddenly appear fully in one of the many creatures on the evolutionary tree where its presence was altogether absent in its ancestor. Eccles in an article “Evolution of consciousness” states that “one cannot expect that consciousness came to higher animals as a sudden illumination. Rather, as with life originating in a prebiotic world, it would be anticipated that consciousness came secretly and surreptitiously into a hitherto mindless world.” (2) This means also that consciousness, while having similarities between creatures, is not all of one type. Thomas Nagel addresses this issue directly in his famous “What is it like to be a bat?” essay:

“Conscious experience is a widespread phenomenon. It occurs at many levels of animal life, though we cannot be sure of its presence in the simpler organisms, and it is very difficult to say in general what provides evidence of it. (Some extremists have been prepared to deny it even of mammals other than man.) No doubt it occurs in countless forms totally unimaginable to us, on other planets in other solar systems throughout the universe. But no matter how the form may vary, the fact that an organism has conscious experience at all means, basically, that there is something it is like to be that organism. There may be further implications about the form of the experience; there may even (though I doubt it) be implications about the behavior of the organism. But fundamentally an organism has conscious mental states if and only if there is something that it is to be that organism—something it is like for the organism.”(3)

The path to consciousness may have begun with the moment a primitive worm-like creature sensed something in its mouth and a nerve impulse triggered it to close and consume the food. It is not an accident that the key organs of four of the five senses and the core neurological mass – the brain – are all located near the oral cavity. From an evolutionary standpoint, consciousness began to find and consume food. It combines the sense organs to find food with the neurological apparatus to direct the organism to catch it and consume it. Later with sexual reproduction the brain and neurological system served to assist in the attraction and selection of mates. Evolution’s somewhat haphazard process of converting, enhancing, and modifying things serving one purpose to other purposes has driven not only increasing neural mass (larger brains) but also the development of specialized structures. Consciousness has not been achieved simply by accumulating additional neurons.

Consciousness thus is related in key ways to metabolism, which, in fact, is the assimilation of order from the environment in thermodynamic terms. The brain and nervous system arose to serve the digestive tract. Consciousness itself is also the assimilation of order from the environment. The order it derives includes perceptual organization and detection of patterns that allow planning and anticipation. Consciousness, in a sense, is metabolism raised to another level.

While the origin of consciousness may be found in the worm, I do not think a worm can be said to be conscious. My preference would be to follow the lead of Eccles in locating the beginning of consciousness with the arrival of mammals and the development of the neocortex, although a good argument could be made there may be some parallel evolutionary process underway with birds. Eccles’ theory relies on the concept that neural units called dendrons that are directly related to a hypothetical psychon or unit of conscious experience. With Eccles the brain and mind meet in the dendron. To quote Eccles: “The hypothesis is that biological evolution induced in the neocortex the design of apical dendrites that is recognized as a dendron and that had as a side effect the capacity for interacting with the world of the mind.” (4) Humans have approximately 40 million dendrons. The most primitive of mammals have about 200,000. The neurological structure is absent in reptiles and fish. Much of the evolutionary development of mammals is accompanied by an increasing mass and new structures in the neocortex.

The connecting link between mind (psychon) and body (dendron) for Eccles is the quantum probability wave. Eccles is not the only one to invoke special physics, especially quantum physics, to explain consciousness and mind. Roger Penrose and Stuart Hameroff build upon Penrose’s argument that consciousness cannot be based on algorithms, hence it is not computable, and suggest that quantum interactions in microtubules, small cylindrical structures for intracellular transport, in neurons might be the source of consciousness.

There is something intriguing about the role of observation in quantum physics and the fact that observation itself implies consciousness. Certainly a key part of consciousness, particularly more advanced forms, is the sense of self-hood. It is the sense of being an entity combined with the sense of an external world apart from ourselves The role of the observer is critical in quantum physics. For example, whether light behaves as a photon or a wave isn’t determined until it is actually measured by an observer. Certainly this suggests that consciousness and the physical world are in some deep way entangled. Mind and matter may create each other rather than one preceding the other.

I discussed Asimov’s The Last Question in a previous post. In the story humans create machines that become conscious. Over time they become more and more intelligent and conscious. Eventually the universe dies as it reaches thermodynamic equilibrium and maximum disorder. The last conscious machines then think the universe back into existence. Universe creates consciousness and consciousness creates the Universe, pointing again to intertwining of mind and matter.

Whether consciousness arises at the quantum level or not, it seems clear that it cannot be explained in mechanistic or reductionist terms by current science. We may need new science to explain how complex structures arise with new properties not explained by their component parts. The explanations may be very specific to the problems of life and consciousness but, more likely, might be a part of bigger theory that explains matter and the universe.

We do not have to buy completely into Eccles’ theory of dendrons and psychons, however, to argue that consciousness began with mammals. The observation of reptiles and fish alone seems to bear out that their behavior is mainly driven by instinct and Skinnerean learning with little capacity for self-directed action. With arrival of mammals, in addition, we have a vast increase in neural capacity along with the development of the neocortex. In addition, we have the observable behaviors such as parenting, nurturing, social interaction, and eventually signaling and symbol manipulation. All of these are associated with increasing development of neocortex. When we look at the evolution of behaviors that we associate with consciousness – planning, nurturing behaviors, cooperation, tool use, signing, symbol manipulation – there seems to be little doubt that consciousness is natural and has a natural history that is clearly associated with an increasingly sophisticated neurological system.

Eccles traces this evolutionary development in his book Evolution of the Brain:Creation of the Self. During the last phases of this development before humans Eccles says: “In the functional symmetry of hominoids the economy of the neocortex was characterized by duplication of all neocortical functions. In hominid evolution we can assume that there was an overwhelming requirement for more neural circuits of exquisite design in order to carry out the large demand for new evolutionary development, especially for the higher levels of language. Hence arose the evolutionary strategy of no longer building more neocortex with dual representation. Instead there would be at birth a left or right propensity for one or other gnostic functions in the delayed maturation.”(5)

Even though Eccles seems to think that with these developments biological evolution largely ceased for humans, I doubt this. Once we evolved as human I believe we have continued to develop new neural structures and have probably undergone at least two separate phase transitions where qualitatively new capabilities arose. The first of these probably occurred 50-100,000 years ago with the development of more sophisticated cultural artifacts, such as art, and presumably with that came additional symbol manipulation capabilities. A more recent transition occurred perhaps as recently as n the last 10,000 years which has made possible mathematics and philosophical thought.

Despite the impressive evolutionary feat that is human consciousness, we may, in fact, at barely the beginning what human consciousness might eventually become (or what other kinds of consciousness on other worlds might already be). It is helpful to remember than even we perform much of the routine activities of our daily lives at lower end of the consciousness scale and perhaps rarely or occasionally are on the upper end. Basic physiological functions operate under the control of the nervous system with little or no conscious interaction. Even activities we perform daily that might seem to require uniquely human capabilities are often performed with little conscious involvement. When I drive to work in the mornings, most of the act of driving is on automatic pilot. If I see a traffic jam ahead from an accident, I might quickly start weighing options to take side roads. After I arrive at work, I might reflect on how lucky I was to not be involved in the accident that caused the traffic jam. In one drive I go from worm to dog to human.

Psychoanalysis has shown how deeply embedded the biological and evolutionary origins of consciousness are with human behavior. Indeed, the first stages of psycho-sexual development are in order oral, anal, and phallic (genital) quite possibly the exact same order in which the matching apparatus evolved in evolutionary time. Even now we have huge amounts of psychic energy bound to basic metabolic functions. Our hunger for knowledge, our need to understand and find order, quite directly comes from the neurological apparatus that supported our consumption of food.

Back in the float tank, I am still very much the worm with a large brain attached. My brain constructs a dreamlike reality that in so many ways is barely different from the awake state of my daily life. Just as normal consciousness pulls order from the world and constructs a reality, my float tank consciousness even in the absence of stimuli builds order. The tank allows me to sit above it briefly to see it for what it is. I enter into state similar to what you might experience before going to sleep. The difference is that I feel myself fully awake through all of the experiences. Memories begin to flood back and I feel myself reenacting experiences from many years ago sometimes with different outcomes. The memories cover very different times and places in my life and seem to jump about randomly. Periodically I come out of this state before drifting back into it. Sometimes I am in the present but feel myself in a different place. After some time I begin to wonder how long I have been in the tank. I imagine myself outside the tank looking at a clock. The clock reads two hours and thrifty-five minutes from the time I entered the tank. I have no way of knowing how accurate that time is but the music to end the session begins to play shortly thereafter so I determine it was probably very close to the correct time. Once the session is over I feel in a very “high” mental state with great calmness. My vision seems more acute. Colors are brighter and detail more clear.

We as humans may be only at the threshold of learning what consciousness is about. We are barely awake and aware now. The freeing of the energies bound to metabolism and the development of new neurological structures may create a new human consciousness.


1- Cage, John. Silence: Lectures and Writings. Wesleyan University Press, 1961.

2- Eccles, John. Evolution of consciousness. Proceedings. Natl. Academy of Science. USA, Vol. 89, pp. 7320-7324, August 1992

3- Nagel, Thomas. What is it like to be a bat? The Philosophical Review LXXXIII, 4 (October 1974): [435-50.]

4- Evolution of consciousness op cit.

5- Eccles, John C. Evolution of the Brain:Creation of the Self, Taylor and Francis e-Library, 2005.

This entry was posted in Brain size, Consciousness, Human Evolution. Bookmark the permalink.

4 Responses to Floating

  1. Rick Searle says:

    Great post James!

    Are you familiar with the work of the neuroscientist Antonio Damasio, especially his most recent book Self Comes to Mind?

    There, he discusses the evolution of consciousness from bacteria to civilization as a kind of feedback system:

    Here is a quote from a review:

    “But consciousness emerges only when – to quote the book’s title – self comes to mind, so that in key brain regions, the representational maps of sensory experience intersect with the encoded experiences of past that self provides. This, enabled by the evolution of language, makes possible autobiographical memory – the narrative of our lives that we humans all possess and which is the basis for consciousness.”


    I think his and your ideas gel quite well on the basis of both this post and your other writings.

    • James Cross says:

      Thanks for stopping by.

      Damasio does sound generally compatible with my view. I will take look at the book you reference.

      I have chosen not to find consciousness at the bacteria level though there may the rudiments of chemistry at that level that eventually develop into something like neurons.

      As the reviewer notes “Consciousness is a term with multiple meanings.”. This is cause of much argument over it. I have decided to put my use of the term at some more intermediate level between bacteria and humans.

      What really interests me, however, is not only where consciousness has come from but where it is going. We tend to think that we humans have somehow reached the pinnacle of consciousness and intelligence where, in fact, we may be just at the beginning of its eventual evolution.

  2. Marilyn says:

    Well, this is the first of your blogs I have been able to stay with almost until the end. I do not have the keen intellect that you have obviously developed over your years. My life is more about experience than the head. I liked it though, there are always parts in your blogs that leave me wondering, “why so many words to make a point”. But since I was interested in what you had to say about the tank I hung in there. I do admire you ability to pull others ideas to make a point for your own beliefs but I sometimes am not sure if you believe what you are writing. It seems that you write and then ask the reader to determine what is true or false. Maybe that is what makes a good writer.
    I love the last part and your description of the experience in the tank. That I can honestly say is a quite accurate accounting of some of the experiences one could have in the “box of SELF-DISCOVERY”. Hope to see you again soon.

    • James Cross says:

      Thanks for commenting and thanks for your tank.

      Do I believe what I am writing? My blog is about speculations. Speculations are informed guesses so they are not matters of belief of which I probably have very few. With more information or thought I might toss any of them aside.

      You say my account is an accurate accounting of some of the experiences one have in the tank. Could you perhaps add some of your experiences?

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