Perception

We take in information about our environment from our senses. Most of us have learned there are five senses, but depending on what you call a sense there can be many more. Perception is what happens when information from all our senses interacts with our short and long-term memory structures to produce awareness of our physical state and immediate environment. When sense information is processed through specific memory-structures these structures are called perceptual sets.

Sense Organs

• The Eye: Rod cells respond to colors, while cone cells respond to changes in depth from light reflection. Both are at the back of the eye, which in turn is focused and moved almost constantly by many small, cooperating muscles.
  
• The Ear: Sound vibrations against the "ear drum" cause fluid to flow over hairs in the inner ear, stimulating the nerves connected to them in certain patterns. Also in the ear is a grain suspended in fluid surrounded by hair-nerve cells. This apparatus senses movement of the head/body, and gives a feeling of balance.
  
• The Nose and Mouth: work together. Chemicals exposed to the tongue stimulate stimulate tastebuds (for sweet, salty, bitter or sour). Chemicals exposed to the back of the inside of the nose stimulate smells (some researchers have named five smell categories: "flowery, spicy, resin-like, putrid and smoky"). As we grow up we forget the power of smell, which as babies we use to identify our mothers and others before we can even recognize faces well.
  
• The Skin: Contains different kinds of nerve receptors for heat, cold, light pressure and strong pressure, and pain. The mechanisms for their stimulation are still not well understood.
  
• Muscles: When muscles move they stimulate nerves connected to them.
  
• Nerves Inside the Body: Nerves that senses pressure, friction, and movement are throughout the body and especially in the stomach, mouth, and genitals. Also, body temperature, and the chemical make-up of the blood are monitored by nerves. Scientists have also pointed out that some nerves sense the passage of time (through timed chemical processes) which would account for cyclic urges, such as hunger, tiredness, etc.

Each sense has a smallest detectable stimulus, listed below. As the intensity of the stimulus increases it becomes more difficult to detect if it changes slightly. At a certain point some stimuli (like bright light, loud noise, or strong pressure) can become painful. Sensations seem strong or weak partly in relation to the state of stimulation before sensation. (Try lifting a heavy weight than a moderately heavy one. Then lift a light weight followed by the medium one. How does your perception of the medium weight change?)

• Vision: A candle seen at 30 miles on a dark, clear night
  
• Hearing: The tick of a watch under quiet conditions at 20 feet
  
• Smell : One drop of perfume diffused into a 3-room apartment
  
• Taste: One teaspoon of sugar in two gallons of water
  
• Touch: The wing of a bee falling on your cheek from 1 cm.
  

This phenomenon of course occurs also with spoken language. As anyone learning a new language will attest, much of what we "hear" (especially when we are not focusing carefully on it) is what we think would be the most reasonable ordering of the sounds we fell we heard into words, given what we know about who is speaking and why.

Not only to all senses work together to give us awareness, but also each sense works "against" itself, as sense data from, say, the eyes, is checked against sense data collected from the eyes a split second ago, to detect change. What we give our attention to are things which seem new, interesting, potentially dangerous, or pleasurable, or helpful to a task we plan to do. The things which most draw our attention are also the things we tend to remember.

How does a baby understand space? Before it can do this, an infant must have a spatial map of its own body. Points on a babies skin which are closer together are more likely to be stimulated at the same time than those that are farther apart. Mathematically speaking it is possible to create an accurate map of a surface just by knowing which points are close together.

Frames are systems for processing which can be used for many related sets of information. Researchers theorize that the mind relies on spatial frames (into which models of objects can be inserted) to process spatial information.

Once a baby has a mental map of its own body (which of course is biased to highly-sensitive regions like the mouth and hands, think of them as peaks on the map) it can begin to explore the shape of the space around it. It does this by relating shapes to its own body and movement, putting things in its mouth, touching things, and walking or crawling across rooms. The ability to imagine a room from many different perspectives is still developing into early adolescence for most people.

This sort of explanation may also help us understand how children come to form models of "meaning space." Concepts which are similar are more likely to be thought about in connection with each other than concepts which are very different. Yellow and red are more likely to be thought of together than yellow and tall, for example, and in this way perhaps the formation of the ability to categorize begins. Later, these categories can be bridged with the use of metaphors, which is the key to understanding new concepts.