The study of signs and symbols is a facet of Analytic Psychology, called semiotics. A sign is an item that suggest presence of fact or a figure that stands for a word, phrase, or operation. They have been created and changed for hundreds of years. It is a form that a person can sense (look, smell, fell) about the object that it signifies.
The sign, the concept, and the object are all related to each other. Metaphors are a sort of sign, and can be used verbally or visually. When designing with images, using metaphors in images is often called Visualizations and can be seen all the time, some are more sophisticated that others. Here is an example, the image is trying to warn against drinking while pregnant, the sign is the beer with a bottle nipple, the concept is a that a baby drinks from this, and the object is the beer being given to a baby. The signification is that when you drink while pregnant, the baby is drinking alcohol too.
This initial information was presented by a small group of students are the beginning of the lecture. Different examples were given and explained in such genres as fine arts, graphic design, and advertisement. After the students presentation, Nicolaj gave a more in depth lecture based on the book: Architecture and Symbols: Learning from Las Vegas by Robert Venturi. The author described architecture in Las Vegas as either being 1) architectural features submerged in a symbol (think a building shaped like a tea pot) or 2) ornament being applied independently of architecture (cesar's palace). Venturi argues that the architectural structure itself should be a symbol of what it is, so that a hotel is visually a hotel and that the ornament act independent from it. Sometimes, symbols can be derived from architecture, as seen with the first McDonald's store. The arching yellow lines later became embodied in the corporate logo.