Visual semiotics

Studies of meaning evolve from semiotics, a philosophical approach that seeks to interpret messages in terms of signs and patterns of symbolism. Contemporary semiotics consists of two branches originating contemporaneously in late 19th century France and the United States. Originating in literary and linguistic contexts, one branch (referred to as semiology) originated from the work of Swiss linguist Ferdinand Saussure. The second branch expands on the work of American pragmatist philosopher Charles Sanders Peirce.

A sign can be a word, sound, a touch or visual image. Saussure divides a sign into two components: the signifier, which is the sound, image, or word, and the signified, which is the concept or meaning the signifier represents. For Saussure, the relation between the signifier and the signified is arbitrary and conventional. In other words, signs can mean anything we agree that they mean, as well as mean different things to different people.

Peircean semiotics works from a different notion of what a sign is. A sign is something that stands for something else (the sign's object) to a receptive mind. The effect the sign has on the receiving mind is called the interpretant. Note that the interpretant may not be identical to the sign's object (something we call a "mis-understanding") but we are eternally prevented from assurance of this match or mismatch because the only way we have of verifying the match is to use additional signs.

In Peircean semiotics, signs that have an arbitrary or conventional relation to their objects are called symbols. But there are two other kinds of sign-object relations which are not completely arbitrary: icons are signs that resemble their objects, and indexes are signs that relate to their objects by some actual contact or environmental contiguity.