Cornell University Ergonomics Web
Cornell University Ergonomics Web
DEA 3250/6510 CLASS NOTES
Ergonomic Considerations for Graphic Design
Graphic Symbols
1. Definition and Qualities - A graphic
symbol (GS) is an optically perceptible figure produced by means of writing,
designing, printing, or other techniques (icon on a computer screen). A
good graphical symbol should transmit a clear and unambiguous message independent
of language, ability, object, or concept. GS are used in static (e.g. stop
sign) and dynamic (e.g. speedometer) displays.
2. Functions of Graphic Displays -
a. Identify - a product, service, action, prohibited action.
b. Qualify - describe a variation of an identity.
c. Instruct - describe an operation or how to use, e.g. safety instructions
on airplanes.
d. Command - indicate that something must be done or must not be
done.
e. Warn - draw attention to danger.
f. Indicate - give types of information like direction or quantity
3. Design Criteria -
a. Image content - Content must be unambiguous.
b. Consistency - Symbol elements must not be similar to elements
used in other graphic images where the element has a different meaning.
c. Easy to Read - Symbol should be easy to read quickly and accurately
and provoke a quick response (especially if it's a warning symbol).
d. Reproducibly - Symbol must be easy to reproduce at any size and
on any print medium.
e. Multiple Symbols - Multiple symbols can be used to augment understanding
but no more than three should be used in a display.
4. Design Process
a. Identify need
b. Identify purpose - Create a clear and unambiguous description of
the purpose of the symbol and identify any position and/or movement information,
e.g. push bar door release.
c. Design graphic
d. Test - symbol for legibility, comprehension, etc., relative to criteria.
Be sure to target the right population.
e. Example - Highway signs (Kline et al, 1991) were tested with eight
men and eight women in each of three age groups: young /24 years 18-34;
middle/54 (45-60); and elderly /69 (61-72). Two lighting conditions (daylight
and dusk) were examined. Results were that people can recognize icons much
better at a distance than text.
5. International Standards -
ISO 3461 (1976) - Graphic symbols - general principles for presentation
ISO/ TR/7239 (1989) - Development and principles for application
of public information symbols.
Click here for a list of ISO Graphic Standards
Basic Pattern (template)
3 squares, 2 circles, 2 rectangles,
and a regular octagon
- build symbols within
6. Principles of Good Symbol Design
-
a. Silhouette is preferable to an outline
(context should be a different color)
b. Only details which contribute to better symbol comprehension should
be included.
c. Left/right symmetrical symbols are preferable to asymmetrical
symbols
d. Symbols which are similar in height and width are preferable to
long narrow shapes. (height: width ratio <4:1).
e. Symbols which convey directional information should be reversible.
f. Size of significant details (M) should be at least 1 mm for every
meter viewing distance.
g. Line width of significant details should not be
less that 1/2 mm for every meter viewing distance.
h. Distance between edge of symbol and inner edge of the enclosure
should not exceed 1-1/2 mm or 2.5 mm if the edges are parallel (per meter
distance).
i. General purpose symbols should be within a 15° viewing angle;
if critical symbol, reduce to <5°.
j. Symbol size, for legibility: Z = .012D (meters) D=distance
Conspicuity - Z = .025D
7. Hazard Signs - Serve safety functions: alert to possible danger,
advise, and avoid injury.
a. Standard Format - has three parts:
(1) Hazard intensity panel - shows the type of warning and reads
either "DANGER", "WARNING", or "CAUTION."
(2) Pictogram panel - Primary alert message identifies nature
of the hazard. (May identify consequences if ignored.)
(3) Instruction message panel - Message on how to avoid the hazard.
b. Key words -
DANGER - when there's an immediate hazard that will result in severe personal injury
or death.
WARNING
- immediate hazard could result in severe personal injury or death.
CAUTION - if immediate hazard could result in minor personal injury.
c. Size - If the sign is large and vertical - stretch the message
panel down. If horizontal - stretch to the right
d. Bilingual considerations - Put the most common language at the center, the next
above, below that, etc.