ICON, INDEX and SYMBOL (Short Version)
Updated Sept 4, 2000 (R. Port), Linguistics L103, Fall,
To the Long Version
There are 3 kinds of sign : the ICON, the INDEX
and the SYMBOL.
from philosopher Charles S. Peirce in the late 19th
a sign is a stimulus pattern that has
The difference is in how the meaning happens
to be attached to (or associated with) the pattern.
The icon is the simplest since it is a pattern
that physically resembles what it `stands for'.
A picture of your face is an icon of you.
The little square with a picture of a printer
on your computer screen is an icon for the print function.
The picture of a smoking cigarette with a
diagonal bar across the picture is an icon that directly
represents `Smoking? Don't do it' (at least it does with
appropriate cultural experience).
Your cat is preparing to jump up on your lap, so you
put out the palm of your hand over the cat.
Words can be partly iconic too. Bow-wow, splash
and hiccup. And the bird called the whippoorwill. (These
are also called onomotopoetic words.)
Also words can be pronounced iconically:
His nose grew wa-a-a-ay out to here.
Julia Childes grabbed that carrot and went
CHOP CHOP CHOP CHOP.
Aw, poor widdow ba-by!
what IS `physical resemblance'? How similar it must
just because we can recognize a picture doesn't mean
any other animal could.
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.
All animals exploit various kinds of indexical signs
Less sophisticated animals acquire them by natural
More intelligent animals learn them.
dark clouds in the west are an index of
for a fish in the sea, the direction of greater
light is the direction of warmer water,
a limping gait is a sign that an animal is physically
a scowling facial expression is an index of displeasure
or concern (to a human),
sensing a pheremone in the air is an
indexical sign (for some insects) that a sexually receptive
member of its own species is located upwind,
a particular alarm call in certain monkeys is
a sign that
the animal directly sensed a particular type of predator
OR has heard another monkey give this predator
a particular pronunciation of a word can
index a particular geographic place or social group.
Indices depend on a statistical regularity of:
part A (the signal pattern) with
part B (the behaviorally relevant situation).
This requires first,
detecting property A
(which is not necessarily simple) and either
learning (or innately knowing) its correlation
with the B.
For humans, many indices are artificial (not
a beep from your oven can signal that the cookies
are ready to be removed,
a red stoplight is a sign that you should stop
your car or risk an accident,
in an animal behavior experiment, a flashing light
could be a sign that food will be available or that a shock
will soon follow.
a person can wave their hand as a sign of recognition
and greeting (though this may be partly iconic too).
Notice that the correlation need not be perfect.
Words are said to be indexical
when they directly point to their meaning. Eg,
Words as Symbols.
Now, what about a noun in a human language? Is English
`KITTY' an index? Evidence in support of this:
A small child and its mother would be likely to say
KITTY in the presence of a cat.
So [kIDi] does partially predict the
presence of an actual cat.
But no. Even if its true that the earliest words are
learned indexically (that is, by pointing).
You and your baby also freely use KITTY when a
cat is NOT around
What percent of the time that you utter the word
ROCKET or TRAIN, is there a physical rocket or train present? My guess:
almost 0% for ROCKET
1-3% for TRAIN.
Many words you have never seen: UNICORN,
GHOST, DEVIL, DINOSAUR.
However, every word has strong associations
with other words that are `activated'
whenever a word is heard or read.
you are more likely to think of (or utter)
these other words after hearing or saying KITTY.
So KITTY may be somehow physically linked to
these other words in the brain.
KITTY may get some of its meaning from the
selective activation of just these associated words
Many word meanings have associates that are component
parts which are also words.
Thus a KITTY has FEET, PAWS, WHISKERS, EARS,
CLAWS, TONGUE, TEETH, TAIL, etc.
A TREE has BRANCH, LEAF, PINECONE, FLOWER,
ACORN, BARK, BIRDNEST, etc.
Many words are also in a hierarchy of superordinate
category words (larger, inclusive categories);
CAT, PET, MAMMAL, ANIMAL, FELINE, FAMILY MEMBER,
Many words have subordinate category
MY KITTY, YOUR KITTY, STRIPED KITTY, TABBY, etc.
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
easily removable from their context, and
are closely associated with large sets of
[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
[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
The most common use of the term symbol is for signs
that are not words:
So, nonword symbols are much like words but often
lack a phonetic form.
Signs have :
Icons have a
physical resemblance between the signal
and the meaning
a correlation in space and time with its
(content words like nouns, verbs and adjectives) are (sound) patterns) that get meaning:
primarily from its mental association with
other symbols and
secondarily from its correlation with