Index/Icon

An Icon is learned an index is not! This is the a very important aspect of obtaining information. Whether you obtain it from learning what it is, or something that you already know and is something that understood by the masses. If you look at a red flower, you already know that it is red, so it is already learned. However if you see this same flower and say that the Italians sure know how to grow flowers, well that is something that you must learn.

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

INDEX

An `index' is defined by some sensory feature, A, (something 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 in dealing with the world. The more intelligent animals are good at learning and exploiting more sophisticated indices (thus a cat will use and learn many more indexical signs than a frog, a fish or an ant -- which tend to be restricted to ones acquired innately).