A SIGN IS A BROAD TERM encompassing a range of concepts. Symbols, indexes and icons are categories within this range. Each of these categories vary in their degree of abstraction. Symbols are the most abstract and are based on convention (everyone agrees on the meaning of the symbol). They don't look like the objects or concepts that they signify. Icons are at the other end of the spectrum. Icons do resemble the objects or ideas that they are referring to (the referent). Indexes fall between symbols and icons in their level of abstractness.

Distinctions are not often easy to make. A map for example, can be argued to be a symbol, an icon or an index with equal justification. Effective communication does not require us to differentiate between these types. An understanding of what sets them apart can, however, make our attempts at communication more effective.

Sewell (1994) classified signs into three categories. Signs that closely resembled what they were referring to were classed as pictorial. Signs that had no visible connection to the concept they referred to were classed as verbal. Verbal signs are more abstract and are understood through learning the conventions that determine their meaning. The words represented on signs are understood only when the viewer learns the meaning of the word. Sewell classifies those signs that fall between pictorial and verbal as graphic.

Eisner (1970) used a similar classification system but added an interesting fourth element which was not a sign in the typical sense. This class included signifiers of atmosphere and were used to evoke feelings. Mood music used in the movie industry is used effectively to signify changes in mood and enhance the visual message.

Research has shown us that symbols are not widely understood and that recognition patterns are determined, to a large extent, by the culture that the viewer comes from (Griffin & Gibbs, 1993; Griffin, 1994). Griffin (1994) pointed out that verbal context can make symbols easier to interpret. Signs, like the steep grade sign below combine a graphic with the words "steep grade". This increases the likelihood that the viewer will correctly interpret the signs meaning. Griffin, Peterson, Semali & Takakuwa (1995) conducted a study in four different countries with four distinct cultures.Their research showed that cultural differences were a predominant variable in the understanding of symbols. Australians, for example, immediately recognize the following sign as the indication that a garbage dump is 14 kilometers ahead. People from a North American culture would be unlikely to understand its meaning. 

The type of sign used in any particular situation is determined by a number of factors. A major factor in this selection will be the intended audience. Signs intended for children must recognize their limited reading abilities. Signs used to communicate to children, need to resemble the items to which they refer. A picture of an ice cream cone will be more effective than a sign with the word 'ice cream' displayed on it for users in this category.

Situations where the users are likely to be restricted by language barriers operate under similar restraints. Airports and other such areas likely to serve travelers with different languages require a more 'iconic' approach to their signs.

Some signs employ a combination of both 'verbal' and 'iconic' techniques which have the potential to convey meaning to a much broader range of users. This 'steep grade' sign uses both of these elements.

Our highways are surrounded by numerous examples of signs falling into all categories. The official state and federal signs are dominated by more abstract examples. These signs, such as the interstate sign pictured here, rely on a uniform convention. The color, shape and words contained in the sign, combine to convey the intended meaning. Users, who in this case are drivers, are trained to recognize their meaning and tested on that ability before being allowed to drive.

As instructional designers we will be called upon to develop instructional products which incorporate a number of signs. The object-oriented user interface is just one example. We need to be aware of our intended audience and ensure the signs we use can correctly communicate the desired information to that group. 

Greg Brososky
San Diego State University
Department of Educational Technology
Advanced Multimedia 561