ICON, INDEX and SYMBOL (Short Version)

Updated Sept 4, 2000 (R. Port), Linguistics L103, Fall, 2000

To the Long Version

There are 3 kinds of sign : the ICON, the INDEX and the SYMBOL.


The icon is the simplest since it is a pattern that physically resembles what it `stands for'.



Defined by some sensory feature, A, (directly visible, audible, smellable, etc) that correlates with and thus implies or `points to' B, something of interest to an animal.


Indices depend on a statistical regularity of:

This requires first,

For humans, many indices are artificial (not `natural'):

Notice that the correlation need not be perfect.

Words are said to be indexical when they directly point to their meaning. Eg,

  • here, there, I, me, you, this, etc.

    Words as Symbols.

    Now, what about a noun in a human language? Is English `KITTY' an index? Evidence in support of this:

    But no. Even if its true that the earliest words are learned indexically (that is, by pointing).

  • It is very rare for the utterance of a word to correlate with the thing it refers to.
  • A word in any language is vastly more complex and sophisticated.
  • Notice that:

    1. You and your baby also freely use KITTY when a cat is NOT around
    2. so the correlation between KITTY and the cat is a very weak
    3. What percent of the time that you utter the word ROCKET or TRAIN, is there a physical rocket or train present? My guess:
      1. almost 0% for ROCKET
      2. 1-3% for TRAIN.
    4. Many words you have never seen: UNICORN, GHOST, DEVIL, DINOSAUR.
    5. However, every word has strong associations with other words that are `activated' whenever a word is heard or read.
    7. `Activate' means:
      1. you are more likely to think of (or utter) these other words after hearing or saying KITTY.
      2. So KITTY may be somehow physically linked to these other words in the brain.
      3. KITTY may get some of its meaning from the selective activation of just these associated words
    8. Many word meanings have associates that are component parts which are also words.

    These word-word relationships (sometimes called word-associates) are critical for anchoring the meaning of a word without depending on a correlation in space and time between the sound of the word and its meaning.

    In summary, symbols are

    [Thus children in the tropics learn words like SNOW and ICE . How? They do know: COLD, WHITE, CLEAR, HARD, SOFT, FLUFFY, WATER, MELT, FALLING, SLIPPERY, etc.]


    when you have learned a basic vocabulary (based in part on indexical relationships), you can bootstrap to many other new concepts and words.


    No living nonhuman animals are able to use word-like symbols.

    [There are some assertions that a few individual animals use a small (< 50 item) inventory of symbol-like units using hand signs or small physical tokens.]

    If this claim is true, it implies

  • a huge divide between humans and nonhuman animals.
  • It means no animal communication systems can be understood as just `simple versions of human languages'.
  • Nonword Symbols.

    The most common use of the term symbol is for signs that are not words:

  • bald eagle for USA,
  • bear for Russia, etc,
  • cross for Christianity,
  • star of David for Judaism,
  • swastika for Nazism,
  • font for a specific product (eg, Coca-Cola, Indiana University, etc).
  • So, nonword symbols are much like words but often lack a phonetic form.


    Signs have :

  • a signal aspect, some physical pattern (eg, a sound or visible shape) and
  • a meaning - some semantic content that is implied or `brought to mind'
  • Where: