Semiotics

The Swiss born linguist Ferdinand de Saussure (1857-1913) is credited with being the father of linguistics and semiotics. Additional key individuals in the development of semiotics were American philosopher Charles Sander Pierce (1839-1914) and Charles William Morris (1901-1979) who developed 'behaviourist' semiotics.

Saussure developed a two-part model comprising of:

1. A signifier - the form which the sign take.
2. The signified - the concept it represents.

The Peirce Model, a three-part model comprising of :

1. Symbol/symbolic: a mode in which the signifier does not resemble the signified but which is fundamentally arbitrary or purely conventional – so that this relationship must be agreed upon and learned: e.g. language in general (plus specific languages, alphabetical letters, punctuation marks, words, phrases and sentences), numbers, Morse code, traffic lights, national flags.
2. Icon/iconic: a mode in which the signifier is perceived as resembling or imitating the signified (recognizably looking, sounding, feeling, tasting or smelling like it) – being similar in possessing some of its qualities: e.g. a portrait, a cartoon, a scale-model, onomatopoeia, metaphors, realistic sounds in‘programme music’, sound effects in radio drama, a dubbed film soundtrack, imitative gestures.
3. Index/indexical: a mode in which the signifier is not arbitrary but is directly connected in some way (physically or causally) to the signified (regardless of intention) – this link can be observed or inferred: e.g. ‘natural signs’ (smoke, thunder, footprints, echoes, non-synthetic odours and flavours), medical symptoms (pain, a rash, pulse-rate), measuring instruments (weathercock, thermometer, clock, spirit-level), ‘signals’ (a knock on a door, a phone ringing), pointers (a pointing ‘index’ finger, a directional signpost), recordings (a photograph, a film, video or television shot, an audio-recorded voice), personal ‘trademarks’ (handwriting, catchphrases).

Photography specific...

French literary theorist, critic and semiotician, Roland Barthes (1915-1980) considered the photograph to have a unique potential to communicate actual events by presenting a completely real representation of the world. Barthes developed his own two-part theory comprising of: 

1. The studium - the obvious symbolic meaning of a photograph.
2. The punctum - that which is purely personal and dependent on the individual, that which ‘pierces the viewer’.

Nonetheless, Barthes was concerned that these distinctions broke down when the personal significance was communicated to others, in other words, those without an invested emotional input could logically rationalise the image and as such it lost its symbolism. 

[We return again to arguments raised by Walton regarding objectivity versus subjectivity of a photograph - does it represent the object now or how the object was then? It depends upon the viewer has invested emotional input!]