Meet Ian Waterman, aged 61 as of 2013. But a number that holds more weight is 42 - the number of years Ian has lived without proprioception, the ability to sense touch and convey information regarding the positions of muscles and joints.
Proprioception is sometimes also known as the sixth sense or Kinesthetic sense.
Before we continue, it is worthy to note that there are more than the 5 senses we know. We have actually clearly defined at least 9 different senses, with some researchers saying that there are about 21. The reason for science not having establish a solid list of senses is due to how one defines what makes a "sense".
The senses of touch, sight, taste, sound and smell are quite generic and easy to define and teach - It is one of the first things we learn in school.
But when you zoom into specifics, one will find out that the sensation of pressure, for example, is received by a specific group of sensory cell types and interpreted by a particular group of regions in the brain which is separate from those responsible for touch.
Proprioception is the sense that allows you to tell where your body parts are and in relation to other body parts. It is because of proprioception that despite closing your eyes, you would still be able to move your hand and touch a specific part of your face.
Here is a short description of walking without the sense of proprioception:
- You can see your leg moving forward, but you cannot feel it.
- When your foot touches the floor, you cannot feel it.
- You do not know that your leg is straight or not without looking at it.
- You also cannot initiate or control your movements
Try to imagine this in your head and how you can even stand straight. To have a better idea of the feeling, think about the time you accidentally missed a step while walking down the stairs - the split second fear that you could not feel the pressure coming from the contact of your foot and the step surface.
It is only after your foot reached another step slightly lower than the one you aimed for did you realise that you missed a step, and then relief sets in.
For those without proprioception, that split second fear is amplified to every moment of your body, but even that is not nearly enough to describe the complete feeling of living without proprioception, though it surely can give you a rough idea of how it is like.
Proprioception is fundamental to our capacity to move in the world.
There are only 10 known cases of people suffering from the loss of proprioception, some of whom suffered from loss of proprioception in certain parts of their body.
In Ian's case, the nerves responsible for proprioception were damaged from the neck down. And yet, Waterman is the only known man who had overcome this rare disability.
From the age of 19 in 1971, Ian Waterman suffered from loss of proprioception from the neck down. But he is not paralysed, and through sheer willpower, dedication and help from physiotherapists, he had regained control of his body through his vision.
As long as he can see his limbs move, he will be able to move them through incredible focus, much like thinking about moving your hand, without ever knowing that you were successful unless you see it happen.
Obviously, this is incredibly difficult to master, but Ian had mastered it to a great degree to which he is able to not only stand and walk, but also use cutlery, write, type, and even navigate his way around the aisle of an airplane while its in flight!
However, if Ian's vision is impaired in any way - such as turning off the lights or simply blocking his field of vision in which he cannot see his hands, he will not be able to perform his unorthodox motor skills.
In the worst case scenario in which the lights were off, Ian will immediately collapses. Without vision, Ian's brain no longer understand its position in space, and he therefore can no longer think about how much force he needs to stand properly.
In his own words, Ian joking describes how difficult in wiping his own ass without knowing where his hand is.
In a similar scenario, in which Ian cannot see his body while lying down, he describes his immediate sensation as panic. This is because the fear of not knowing is quite daunting. Without visual confirmation, Ian does not know his body is positioned from the neck down.
This fear is natural, because without feedback, one doesn't know whether his body is safe. And while his sense of proprioception is lost, his other senses, such as his sense of pain and temperature, are still working normally.
Ian's case has been the study of many researchers, trying to further understand the human body.
His mastery of his own body in the absence of proprioception may also form a solid foundation of control in the field of human robotics, in which scientists have invented mechanical arms and other robotic limbs that are controlled by the human mind.
Much like the case of Ian Waterman, it is like controlling a body while not receiving much sensory feedback, if any at all.
His story is featured in a 1998 documentary entitled "The Man Who Lost His Body".