Two Point Discrimination

We live in a bubble of interpretation, building a world around us piecemeal from the myriad of detective devices built into our frames. Information is recorded via physical or electrical media, interpreting pressure, chemicals, or light into coded patterns, messages which our brain instinctively interprets.

We feel the outside world via a series of pressure sensors. These sensors read vibrations and force, interpreting the combination into an understanding of texture and position. They combine with internal architecture, stretch receptors reporting the position of your joints. The brain synthesizes the feeling of pressure against your fingertips with the position of your muscles and bones, painting a picture by numbers of what it is you hold.

Your brain portrays the illusion of continuity, of a physical understanding of what you touch, and what is touching you. The distribution of nerves controls how precisely you can feel, allowing your fingers to read braille, while your legs can barely report more than contact. The phenomenon of sensory acuity is described by the phrase "two point discrimination." In the finger tips, you can feel two different points of contact at minute distances. In the back, the distance goes up to centimeters. I can hold two pens in my hand, touch them to your back at the same time, and your brain will report only one touch. The astonishing nature of this is not in your inability to discriminate, its in your brain's absolute conviction that there is only one pen. Even knowing full well that someone is holding two pens to your back, the only result is a cognitive dissonance between known and observed reality.

I marvel at this, the fact that your body and perception can so convincingly lie to you. It is very mystical in its implications, the idea that the physical, the body, cannot be trusted.