Icons, Indices and symbols
Likenesses, Indications, and Representations.
To summarize these 3 concepts in my own language:
Icon: Groups a number of concepts based on similar physical properties, shared behaviours, or relations.
Index: Signifies a specific position along a scale(time, space, color, weight, happiness, wealth, etc)
Symbol: Groups concepts and the relations between them into a process which unfolds in stages over time.
What will/has become of these three core concepts of visual language?
We can be sure that Icons have made the experience of GUIs much more pleasant. Rather than purely text menus and buttons, we now have visual metaphors for the functions of our computer. A music player: a CD and a music note, A web browser: a fox around a globe, An FTP program: a transport truck.
Computer Icons have generally remained in the sphere of Likeness. A CD is like an mp3 because it contains music, a truck is like an FTP because it move things, a globe is like the web because it is world wide.
The advantage of the likeness based visual language is it's easy adoption. Users can quickly associate known nouns with new ones. In fact, the whole graphical operating system is based on metaphors: windows, buttons, check boxes, files, folders, "scroll"bars, pages, etc...
The disadvantage of such an approach is it's tendency to stifle new ways of visual thinking, new languages free of stale metaphors.
I would like to see Icons become Indices, and applications become symbols. To see an icon which represents the complex information contained in it's application. To see an application which begins as a symbol for itself and evolves to a new symbol over the period of use.