What do we call it: Sensory Deprivation Tank, Isolation Tank, Floatation Tank?

This is an amazing post from the Samadhi Tank Company. If you are curious about the history of Floatation Therapy it is definitely worth reading. Enjoy!


Original Art Work by Tia Davis courtesy of FloatOn

Is the term Sensory Deprivation Tank a misnomer?

We find it to be more of a Sensory Enhancement Tank. Listening to your heart beat, muscles pop, eyelids blink, and taking, the time and space to actually feel your breathing rise and fall ­ in all these ways and more a Floatation Tank actually enhances the senses.

But the terms Sensory Deprivation Tank and even the solemn sounding Sensory Deprivation Chamber are already ensconced in the collective conscious, and we have spent years reflecting on all of the terms used to describe this place where nothing happens.

Concern that sensory deprivation tank increases some people's fears We have always avoided using the phrase Sensory Deprivation Tank. For over 40 years we have worked to allay peoples' fears about floating. Darkness and drowning were reason enough for people to avoid the tank, let alone an idea as heavy as sensory deprivation!

Is sensory overload a problem?

But we've realized that in today's world sensory overstimulation is a very real problem, and the younger generations are actively seeking ways to turn off the constant stream of information coming at them from every direction during most waking moments. Today, people are drawn to the potential of darkness and silence.

And yet, the float experience is truly not a sensory deprivation experience. In this article, we explain the history of all the terms used for the tank over the years­ their origins, their meanings, and how they got intertwined and misappropriated.

A History of Sensory Deprivation

In the early 1950s scientists at McGill University, under the direction of D.O. Hebb and funded by the Canadian Defense Research Board, began a series of experiments on what they labeled sensory deprivation. The rationale given for the program at the time was to study hallucinatory perceptual phenomena experienced by people with monotonous jobs ­ radar observers, radio monitors, and truck drivers who commonly experienced sensory distortions.

Original purpose of sensory deprivation research

In 1957 Scientific American wrote: "The aim of this project was to obtain basic information about how humans would react in situations where nothing was happening. The purpose was not to cut individuals off from any sensory stimulation whatever, but to remove all patterned or perceptual stimulation, so far as we could arrange it." 

The covert reason for the research

However, it was later revealed that beneath the desire to study the phenomena stated above was another motivation, which the original researchers kept secret. Hebb revealed this in the introduction he wrote to the 1961 book Sensory Deprivation, writing: "The work we have done at McGill University began, actually, with the problem of 'brainwashing'. We were not permitted to say so in the first publishing. What we did say, however, was true ­ that we were interested in the problem of the effects of monotony on the man with a watch­keeping job or other tasks of that sort. The chief impetus, of course, was the dismay at the kind of 'confessions' being produced at the Russian Communist trials. 'Brainwashing' was a term that came a little later, applied to Chinese procedures. We did not know what the Russian procedures were, but it seemed that they were producing some peculiar changes in attitude. How? One possible factor was perceptual isolation and we concentrated on that."

Research method of sensory deprivation

This was done by placing an adult male subject in a room (or "chamber") reclining on a bed where he would wear a translucent plastic visor which let in only diffuse light, cotton gloves and cardboard cuffs to prevent the hands from feeling anything, and a foam rubber pillow around his head plus the low white noise of an air unit to block any external sound. Time outs were allowed only for meals and bathroom breaks.

Researcher disagrees with the term

However, as Jack Vernon, a researcher who continued the sensory deprivation studies at Princeton and author of Inside the Black Room: Studies of Sensory Deprivation, points out, even in this extreme environment the term sensory deprivation is a misnomer: "Now obviously we did not, and could not, take entirely away the action of all the senses. It is possible to deprive the visual sense totally extinguishing light, but it is not possible to do a similar thing with hearing. Even if a man is placed in a completely soundproof chamber, where no external sounds will reach him, he will still experience auditory sensations. He will hear blood coursing through those blood vessels that are near the ear. He will hear his breathing movements as well as occasional rumblings from the stomach, and the like. It is easily possible to prevent sensations of odor and taste by merely removing stimuli, but man must eat and food, of course, serves to stimulate both of these senses. In addition to these, the mind also receives sensory stimulation that informs it of bodily movements, body positions, movements of muscles, changes in temperature, feelings of thirst and hunger, etc. Thus it can be easily appreciated that to deprive a man totally of sensory stimulation would be a very difficult, if not impossible, task (emphasis ours)."

How it became popular

So if the term sensory deprivation isn't even accurate when describing these early chamber experiments, how did it come to be associated with floatation tanks, which hadn't even been invented when this research was first taking place? We think that films such as The Manchurian Candidate (1962), The Mind Benders (1963), and Altered States (1980) contributed to the use of this misnomer in the popular culture. In addition to that it started being used in beginning college psychology text books. 

Let's turn now to the most famous figure on the history of floating, John C. Lilly, to learn how he invented the floatation tank and why he preferred using another term altogether.

John Lilly & the Isolation Tank

John Lilly did not do sensory deprivation research. There is a common misperception in the float community that John Lilly developed the tank as a part of the sensory deprivation experiments described above. He clarified this misunderstanding in a 1956 paper that was reprinted as Chapter 9 of his book The Deep Self:

"The longest exposure to isolation on the largest group of subjects has been carried out in Dr. Donald Hebb's Department of Psychology at McGill University by a group of graduate students. We started a similar project independently with different techniques at the National Institute of Mental Health. In the Canadian experiments, the aim is to reduce the patterning of stimuli to the lowest level; in ours, the objective is to reduce the absolute intensity of all physical stimuli to the lowest possible level." 

What Dr Lilly was doing

Lilly developed the idea of a tank filled with water with which to accomplish that reduction of the intensity of physical stimuli. This was in response to the prevailing idea in science at the time that consciousness was not primary but was a result of interaction with the material world ­ that if there were no sensory stimuli coming at a person the brain would cease to function. Lilly, who had been fascinated with the subjects of reality and consciousness since childhood, wished to scientifically explore this idea and find the truth.

The tank was born.

Lilly soon realized the enormous potential of what he had created, and started spending many hours in the tank as its benefits became more and more apparent. He started to call it an Isolation Tank in appreciation of the fact that it isolated the person from external distraction and allowed for a spacious inner solitude. He writes in the prologue to The Deep Self:

"In 1954 when I was floating in the silence, darkness, wetness, alone, after the 1st ten hours, I called it Isolation-Solitude-­Confinement-­Happiness-­Freedom-Domain. I realized that no one at that time would believe me if I used that name: they were still caught in belief systems in which what I was doing was to be feared and avoided because one was in Sensory Deprivation. I knew nothing of Sensory Deprivation. I found the tank was and is a vast and rich source of new experience or "inperience" as Franklin Merrell­Wolff calls it. One is not deprived, one is rewarded" (emphasis ours).

His research expands

Lilly became interested in the subject of isolation in general after experiencing the benefits of his time in solitude, isolated from the constant demands of other people, sensory stimuli, and the effects of gravity. This line of inquiry led him to undertake a systematic study of the literature of the effects of extended periods of time spent alone, due to extreme and unusual situations such as shipwreck or accidents in extreme conditions in remote parts of the world. After reading numerous accounts of this kind he came to the common sense conclusion that "physical dangers combined with solitude are very stressful."

Difference between Isolation Tank and other situations

However, solitude without danger are stressful. This confusion between factors responsible has been perpetuated in the 'sensory deprivation' literature... If one eliminates external sources of low­level pain and sources of danger, the inner experience can be anything that one can allow oneself to experience." (The Deep Self, Chapter Three, Peace in Physical Isolation Vs. Sensory Deprivation) In other words, isolation is a totally different experience for a person in a safe, relaxed environment than it is for someone in a stressful, dangerous environment (which many participants in the original, non­water sensory deprivation chamber experiments felt they were in). 

As Lilly points out, and this idea would be a driving force in his life, isolation in a safe space allows ones consciousness to expand and explore anything the person can allow themselves to imagine. This is a powerful idea that has been corroborated by countless people since Lilly's time. The safety, isolation, and peace offered by the tank allow the mind the freedom to expand to unfathomable reaches of the conscious universe.

"This does not say that physical isolation and Today, physicists have proven what ancient wisdom traditions have always said through their stories and mythology­ that consciousness is the primary force in the universe. John Lilly's isolation tank experiments confirmed this as well. Rather than the absence of external stimuli causing the inner awareness to go dormant, it allows for a vast opening of latent possibilities within each individual's consciousness. In the tank, isolation gives way to a boundless inner spaciousness. 

How It Became a Floatation Tank

In the early 70s Glenn Perry, a taciturn computer programmer working at Xerox, took a workshop for five days near Big Bear, California with John Lilly and got to try out a makeshift Isolation Tank. His first experience changed his life and, with John's blessing and mentorship, he became the first designer and manufacturer of tanks for the public.

Glenn took what Lilly had learned over the years and developed a tank design that would allow for commercial production so that others could have access to this experience. He says: 

"John first tried an 8'x8'x8' tank of fresh water in which the person was submerged wearing a breathing apparatus. He quickly realized he could use a shorter tank, get rid of the equipment, and keep his face above water in order to breathe. During John's first 18 years of research, he laid on his back in 20" of water and bent his legs at the knees with his feet standing on the bottom, so he would not sink below the surface. After breathing out, he needed to quickly breathe in so his head would not slip under the surface.

John switched from fresh water to using ocean water going through a tank when he moved to the Virgin Islands to study dolphins. So when he was giving me information about first designing the tank, he mentioned I could add 3% sodium chloride to help me be more buoyant. I am not very buoyant so instead I added 10% salt and when he tried it, he suggested we go up to saturation with the density. Since it was a little abrasive to the skin, he then suggested we switch to magnesium sulfate, epsom salt, which turned out to be better. This allowed the Isolation experience to be enhanced into a Float experience. My partner Lee and I then rechristened them Floatation Tanks as that was less threatening than isolation tanks. Neither John nor we ever would consider calling them sensory deprivation tanks.

Today, of course, they are known most widely under the Floatation Tank name. It's the Float Tank, the Float Industry, the Float Conference, the Float Community. But many people still refer to them as Sensory Deprivation Tanks and, less commonly, Isolation Tanks. 

Want your senses to be deprived?

Even though many who seek a Float experience desire relief from sensory overload, no one will ever experience sensory deprivation in a float tank. Nor did anyone experience sensory deprivation in the chambers designed in the 1950s. If your senses are registering zero input then you, dear soul, have transcended your body and passed on. The best that those of us who are still embodied can do is to seek spaces where our senses can rest, our mental chatter can subside, and we can allow our inner vastness to emerge.

The floatation tank is a place to minimize the information coming into the sensory processing channels of the body, to be isolated from the stressors that await in the outside world, and to let our limitless consciousness float in the peaceful womb of earthbound zero gravity.

The following was written by The Samadhi Tank Co. Inc. © Copyright, 1997, 2014. All Rights Reserved. 

Images Courtesy of FloatOn. Original artwork by Tia Davis.