In the early 1950’s, Dr. John C. Lilly, a MD with training as a psychoanalyst and specialist in experimental neurophysiology set out to study areas of neuropsychology. He reasoned that the best way to study the brain/mind was to isolate it from external stimulation. At this time, there were two main schools of thought about brain activity. The first school of thought was that the brain needed external stimulation to remain conscious, and that sleep resulted as soon as the brain was free of this external stimulation. The second school of thought was that the brain’s natural cellular circuitry was autorhythmic and continue without any external stimulation.
He started his study of sensory deprivation in a tank constructed during WWII for experiments by the navy on the metabolism of underwater swimmers. This tank had the floater suspended upright, entirely underwater, head covered by a breathing apparatus and mask.
During his initial experiments, he described what happened to our minds and bodies when categories of external stimulation were eliminated:
People – There are no other people in your float tank, so there is no need to worry about social roles, or what you look like. You can be free from any expectation of others in a float tank.
Light – A large portion of our cerebral cortex is given over to visual processing. When we eliminate light from our environment, our ‘biocomputer’ continues to generate ‘visual displays’, presumably from stored memories.
Sound – Like light, when external sound is eliminated, the internal ‘biocomputer’ fills the acoustic sphere with information. He called these internal sounds ‘sonic displays’.
Gravity – In our everyday activities, and below our level of awareness, we are constantly computing the direction of gravity. Floating in water distributes the countergravity pressure over a maximum possible area, therefore reducing this source of stimulation.
Temperature – In everyday life, our skin is stimulated by changes in heat, humidity, clothing. Changes in temperature and heat flow are powerful programmers for our state of well-being.
It is interesting to note, that in the mid-1950’s, the thinking was that sensory deprivation was a road to ‘madness’. Instead, what Dr. Lilly found was a ‘richly elaborate state of inner experience’. “This environment furnished the most profound relaxation and rest that he had ever experienced in his whole life”. Within a few hours of his first satisfactory float, he was able to scientifically conclude which school of thought was correct – that the brain was indeed able to sustain itself in the absence of external stimuli.
Dr. Lilly continued his work to develop much more user-friendly float environments that are the basis of the float tanks that we know and love today.
Next time you are in to the shop, feel free to browse our sources of information for this article – “Centre of the Cyclone” and “The Deep Self”, by Dr Lilly as well as “The Book of Floating” by Michael Hutchinson.