Primal, Acute and Easily Duped: Our Sense of Touch

[groovedaddy]

Imagine you’re in a dark room, running your fingers over a smooth surface in search of a single dot the size of this period. How high do you think the dot must be for your finger pads to feel it? A hundredth of an inch above background? A thousandth?

Well, take a tip from the economy and keep downsizing. Scientists have determined that the human finger is so sensitive it can detect a surface bump just one micron high. All our punctuation point need do, then, is poke above its glassy backdrop by 1/25,000th of an inch — the diameter of a bacterial cell — and our fastidious fingers can find it. The human eye, by contrast, can’t resolve anything much smaller than 100 microns. No wonder we rely on touch rather than vision when confronted by a new roll of toilet paper and its Abominable Invisible Seam.

Biologically, chronologically, allegorically and delusionally, touch is the mother of all sensory systems. It is an ancient sense in evolution: even the simplest single-celled organisms can feel when something brushes up against them and will respond by nudging closer or pulling away. It is the first sense aroused during a baby’s gestation and the last sense to fade at life’s culmination. Patients in a deep vegetative coma who seem otherwise lost to the world will show skin responsiveness when touched by a nurse.

Like a mother, touch is always hovering somewhere in the perceptual background, often ignored, but indispensable to our sense of safety and sanity. “Touch is so central to what we are, to the feeling of being ourselves, that we almost cannot imagine ourselves without it,” said Chris Dijkerman, a neuropsychologist at the Helmholtz Institute of Utrecht University in the Netherlands. “It’s not like vision, where you close your eyes and you don’t see anything. You can’t do that with touch. It’s always there.”

http://www.nytimes.com/2008/12/09/science/09angi.html

[amdezurik]

1. a case can be made that we only have one "sense", touch

after all we only see because light "touches" certain spots that react in a particular way to different freqs of light. the only reason we hear is that sound wave "touch" our eardrums (and shake the floor so we can "hear" through our feet). and we can only smell because certain spots in our sinus cavity when "touched" by substances that match them react.

[Nihil]

2. K & R for a fascinating article ...

... and nicely written, particularly these two points:

> It is an ancient sense in evolution: even the simplest single-celled
> organisms can feel when something brushes up against them and will
> respond by nudging closer or pulling away.

> It is the first sense aroused during a baby’s gestation and the
> last sense to fade at life’s culmination.

Thanks for posting it!
:toast: