The concept of perception is broad and can cover many topics. One of the most fundamental tools of perception is called proprioception. Proprioception is defined as the awareness of ones body. This sense allows humans to move their limbs and navigate through space but more importantly it allows them to calculate how much force to apply to pick up an object or just how far away an object is.
The ability to make these calculations is facilitated by sensory receptors that are found in human tissue such as muscles, joints and tendons. Proprioception is so important that without it, a person would not be able to function. The loss of proprioception not only effects the ability of locomotion through time and space but also the sens of self or the mind. In The Man Who Mistook His Wife For A Hat, Oliver Sacks speaks of a patient, Christina, who had lost her proprioceptive sense “she continues to feel with the continuing loss of proprioception, that her body is dead, not real, not hers- she cannot appropriate it to herself. She can find no words for this state” ( Sacks pg.50)
The proprioceptive sense, sometimes referred to as the 6th sense or the hidden sense, has two components, neither of which we are aware of on a regular basis. The first is the ability to sense ones extremities when still. This part of proprioception is the part that allows humans to be able to sense where their limbs are at any time. Upon waking in the morning, the brain is able to sense that, perhaps, one foot is hanging off the bed or an arm is under the pillow. The second part of the proprioceptive sense is the ability to be aware of the movement of the extremities. This component allows for the calculations necessary to move, to walk. Without this second component it would be hard to “tell” the limbs how far an object is or how much force to apply to pick it up. Sacks says this about Christina, a patient who he called “The Disembodied Woman”, ” Standing was impossible- unless she looked down at her feet. She could hold nothing in her hands, and they ‘wandered’- unless she kept an eye on them. When she reached out for something, or tried to feed herself, her hands would miss, or overshoot wildly, as if some essential control or coordination was gone” (Sacks pg.43)  Unfortunately there is no cure for proprioceptive deficincies. Christina had to learn to do everyday tasks using her sense of sight, she still has a feeling of disembodiment and her quality of life is not what it once was.
Christina’s case is rare but studying cases like hers will hopefully tell scientists and researchers more about proprioception. The study of the brain is still very much in its infancy, hopefully in the years to come research will find solutions for people like Christina. For more information on Interesting cases like these, read The Man Who Mistook His Wife for A Hat” By Oliver Sacks. It is by far one of my favorite books and a lot of the conditions tie in with the concepts of Cognative Psychology.

Proprioception. (n.d.). Retrieved September 12, 2015, from http://cirrie.buffalo.edu/encyclopedia/en/article/337/

Sacks, O. (1985). The man who mistook his wife for a hat and other clinical tales. New York: Summit Books.