An additional note on invisibility comes with the manner in which visual symbols communicate (or do not communicate) messages. For instance, what should the symbol in Figure 1 represent? For someone in the developed world, this represents many things -- sound, amplification, radio, communication, and so on. But, like in the movie The Gods Must be Crazy, in which a Coke bottle falls from a plane and is picked up by a Bushman, what reference would some cultures have to the symbol? Now, if we contrast that with Figure 2, we find a more universal, but still subjective icon -- could it be growth, love (a Western concept), gardens, beauty, purity, sorow, etc. Each one of these is "invisible" in the sense that there can be as many interpretations as there are readers. When one combines this with a multi-panel comic (say in a newspaper or magazine) or graphic novel, then the interpretations of invisibility increase exponentially.

If we think of graphics as mind maps, and thing of the interpretation of...

A blank red octagon will likely tell most people to "stop" even without the words; a picture of a cross has different meanings, many religious; pictures of iconic myths and stories communicate more than just their prose, but morals, ethics, and cultural norms. This, in fact, is the invisibility of the comic -- the fact that the visual image, the type set, the setting, colors if used, etc. all contribute to the story and are available for all readers, regardless of culture, educational level, chronology, or age -- as long as there are appropriate cognitive skills.
Bibliography

Horrocks, D. "Inventing Comics." June 2011. Comics Journal. Web. Feburary 2013. .

McCloud, S. Understanding Comics: The Invisible Art. New York: William Morrow, 1994. Print.

Figure 2