Signs typically have an iconic or cause and effect connection to their referents

Signs, in addition, are often easy to learn. In some cases there is a genetically based connection, like in the bee's dance. In many cases there is an iconic (look-alike) connection between the sign and the thing it indicates.

A human footprint in the sand, for example, resembles a human foot and indicates that someone was there recently. For people like Robinson Crusoe , who was alone on a desert island in a part of the world inhabited by cannibals, this was definitely a call to action--look out! (See the notes for an example of a signs which is both iconic ad cause and effect.)

Signs are often connected by a cause and effect relationship to their referents (the things they indicate).