Susanne Langer differentiates SYMBOLS (word-like units) from mere SIGNS (also called INDICES by Terrence Deacon and C. S. Peirce). This page is an attempt to sharpen the difference between these two.

SIGN

A `sign' is defined by some sensory feature, A, (something directly available) that correlates with and thus `points to' B, (something of interest). All animals exploit various kinds of signs in their interaction with the world. The more intelligent animals are better at learning and exploiting more sophisticated signs (thus a cat will use and learn many more signs than a frog, a fish or an ant).

Thus,

1. dark clouds in the west are a sign of impending rain,
2. a limping gait is a sign that an animal is physically impaired,
3. a scowling facial expression is a sign of the person's displeasure or concern (to a human),
4. sensing a pheremone in the air is a sign for some insects that a sexually receptive conspecific (member of its own species) is either nearby or upwind,
5. a particular alarm call in certain monkeys is a sign that the animal has either directly sensed (eg, seen, smelled, heard) a particular type of predator or has heard a conspecific give this alarm call.
6. a particular pronunciation of a word is a sign that someone comes from a particular geographic place or social group.

Note that all of these above depend on a certain statistical regularity of part A (the signal part) and part B (the behaviorally relevant part). The exploitation of this regularity requires first, detecting property A (which is not necessarily simple) and either learning or innately knowing its correlation with the B. In that case the animal can use A as a sign of B.

But some signs can be artificial and manmade (rather than natural or innate to particular species):

1. a beep from your oven can signal that the cookies are ready to be removed,
2. a red stoplight is a sign that you should stop your car if you don't want to risk an accident,
3. in an animal behavior experiment, a flashing light could be a sign that food will be available in a certain place or that a shock will soon follow.

SYMBOL

Words as Symbols.

One place to begin is to ask `So isn't a word like KITTY just another kind of sign?' In support, you might note that a small child would be likely to say KITTY in the presence of a cat. Since the sounds [kIDi] correlate with the presence of cat (so A predicts B), doesn't that show that this is just a sign like those above? This may be so, but a word in any language is vastly more sophisticated. Notice that:

1. You and any child will also use the word KITTY when a cat is NOT around without the slightest difficulty. (If your dog knows the `word' TAKE-A-WALK, try just discussing taking a walk in earshot of the dog and see what happens! Dogs have no grasp of `Talking-about-a-walk') Indeed many names of things describe objects that noone has ever seen (like MONSTER, UNICORN, GHOST, etc).
2. Any word has strong associations with other words that are `activated' whenever a word is used. Thus KITTY activates words like CAT, FUR, BABY, PURR, PUPPY, PLAY, SAUCER, MILK, YARNBALL, CATFOOD, etc.
   By `activate', I mean that you are more likely to think of or utter these other words after hearing or saying KITTY. (There are many kinds of experimental evidence for this, plus intuition.) This suggests that KITTY may be somehow physically linked to these other words in the brain - that, in fact, KITTY gets some of its meaning from the selective activation of these particular words (and their associated emotional content) when KITTY is spoken.
3. Many words describe things that have component parts. Thus a KITTY has FEET, PAWS, WHISKERS, EARS, CLAWS, TONGUE, TEETH, TAIL, etc. A TREE might have a BRANCH, LEAF, PINECONE, FLOWER, ACORN, BARK, BIRDNEST, etc
4. Many words are situated in a hierarchy of superordinate categories (that is, larger, inclusive categories) like CAT, PET, MAMMAL, ANIMAL, FELINE, FAMILY MEMBER, etc.
5. Many words have a hierarchy of subordinate category subtypes: MY KITTY, YOUR KITTY, STRIPED, TABBY, etc.

In short, a symbol such as a word in a human language is easily removable from its context. Indeed we easily learn many words for things we have never experienced. Children who grow up in the tropics learn to correctly use words like SNOW and ICE without ever seeing snow or ice! No problem. They have heard descriptions of them in terms of words they do know, like COLD, WHITE, CLEAR, HARD, SOFT, FLUFFY, WATER, FALLING, SLIPPERY, etc. From these descriptions, they get at least some idea what these things are like - enough to read and produce the words appropriately.

This is the enormous power of human words: When you have learned a good sized vocabulary, you can use it to bootstrap to many other concepts and words. Given the possibility of cultural transmission from generation to generation, knowledge and understanding become cumulative at a very rapid rate (relative to the creation and transmission of innate knowledge).

IMPORTANT CLAIM: Apparently no living nonhuman animals are able to use word-like symbols that have properties resembling those above. There are, however, some (disputed) claims that a few individual animals (mostly higher primates like monkeys, chimpanzees and gorillas) have been trained by humans to use a small (< 50) inventory of symbol-like units using hand signs or small physical tokens.

Nonword Symbols.

Words (especially nouns, verbs and adjectives) seem to be the architypal symbols. But the most common use of the term symbol in everyday language is for nonwords: a flag or totem animal as the symbol of a country (bald eagle for USA, bear for Russia, etc), a cross for Christianity, star of David for Judaism, swastika for Nazism, etc.

It seems like a similar set of associations to other words can be made for such symbols. Thus, the US FLAG (I mean the graphic pattern in red, white and blue, not the English word FLAG) gets its meaning partly from its association to words and concepts like: HOMELAND, WASHINGTON, BALD EAGLE, PATRIOTISM, MOM, DAD, APPLE PIE, PRIDE, HEROISM, DEMOCRACY, `OH SAY CAN YOU SEE...', `I PLEDGE ALLEGIANCE...', SACRIFICE, etc etc.