Components of Perceptibility in Symbol Signs

Easterby (1970) : described symbol signs as having five basic components:

(a) pragmatic, the context in which the symbol will be used;

(b) semantic, the symbol's relationship to its referent;

(c) syntactic, the symbol's relationship to others in the set,

(d) visibility, how well the symbol can be seen;

(e) discriminability, how well the symbol is differentiated from others.

Vizualization of Easterby's five components of symbol perceptibility (Boling, Johnson & Kirkely, 1994)

Each of the five components affects the other four and contributes to the symbol's overall perceptibility. No one component alone determines a symbol's effectiveness.

On this page we demonstrate the five components of perceptibility using a fictional HyperCard stack entitled Student Research Assistant. The symbol/sign used for each demonstration is the button Notecards, which contains both a pictorial sym bol and a text label. The Notecards button provides access to research notecards the student has created previously.

Pragmatic component

The pragmatic component is a symbol's context. The viewer's ability to perceive the function of the Notecards button accurately is affected by the context in which the button is encountered. A symbol's context has multiple components. In th is example, the name and implied function of the stack itself are one component, the symbol's grouping with three others by virtue of their similar visual treatment is another.

Semantic component

The semantic component is a symbol's relationship to its referent. This relationship may be concrete, as is the case when the image of a pencil is used to indicate the pencil tool in an electric palette. The relationship may also be abst ract, as is the case when a red circle is used to mean "stop."

Syntactic component

The syntactic component is the symbol's relationship to the entire symbol set of which it is a part. The location of the symbols in relation to each other is part of the syntactic component for any one symbol in the set, as is the symbol's positio n within the frame of the stack.

Visbility component

The visibility component refers to whether the symbol may be seen at all, and with what degree of clarity. Although visbility would seem to be the easiest component to acheive effectively, it can suffer when a symbol is moved from a color display to gray-scale or black and white, or when the viewer suffers from color-blindess or lack of visual acuity.

Discriminability component

The discriminability component describes how well a symbol may be differentiated from the others in a set. Symbols differing from each other only in detail may not be sufficiently differentiated for the viewer to identify reliably the one he wants.

References

Boling, E., Johnson, L., & Kirkley, S. (1994). A quick and dirty dozen: guidelines for using icons. HyperNEXUS, 4(2), 5-7.

Easterby, R. S. (1970). The perception of symbols for machine displays. Ergonomics, 13(1), 149-158.