Research Update

The Human Centered Systems

Research Program addresses human

performance-related issues that affect

highway system design. Current

human centered research focuses on

Highway Safety and Intelligent

Transportation Systems (ITS).

Human centered research products

include driver performance models,

highway system design guidelines,

and handbooks based upon empirical

human performance data collected in

the laboratory and in controlled,

on-the-road tests.

Research, Development, and Technology

Turner-Fairbank Highway

 Research Center

6300 Georgetown Pike

McLean, Virginia 22101-2296

DESIGNING EFFECTIVE

IN-VEHICLE ICONS

Introduction

This research update provides general human factors design information relevant to

the early phases of in-vehicle icon development and design. It reflects a subset of the

results to-date of a Federal Highway Administration (FHWA) project to develop a set

of clear, concise, and user-centered human factors design guidelines for in-vehicle

icons. An important element of this project is the involvement of a project working

group, comprised of over 20 representatives from the icon design, in-vehicle information systems, and human factors communities. This group has served as subject

matter experts and consultants to the project, helping to ensure that the resulting

design guidelines conform to icon designers’ specific needs with respect to content,

organization, and format.

Icons are visual representations or images used to symbolize an object, action, or

concept. Icons are among the oldest forms of communication and provide a number

of advantages over a text-only approach to presenting drivers with in-vehicle messages. For example, icons: (1) may be recognized more quickly and accurately than

text-only messages, (2) can be presented in a much smaller area than can text, and (3)

can convey information across many languages and cultures.

Despite the obvious applicability of icons to the design of ITS, such as advanced

traveler information systems (ATIS) and collision avoidance systems (CAS), poorly

designed icons can lead to driver confusion and errors and actually exacerbate

existing traffic problems. Although the use of icons is widespread, few guidelines

exist that can be confidently used by vehicle and electronics designers during icon

development. The lack of guidelines, standards, and a systematic framework to aid

icon design has resulted in design by consensus for many ITS-related icons, a lack of

scientific rigor in icon development, non-intuitive, and difficult-to-learn icons for invehicle messages, and multiple icons for the same message.

Human Factors Design Guidelines to Increase Icon

Effectiveness

Critical to icon development is a basic understanding of what icons are, as well as

general procedures that can be used during icon design in order to maximize their

effectiveness when used by the driving public. Of the 36 preliminary design guidelines that have been produced for this project, an entire chapter (6 guidelines) has

been devoted to such basic design issues. Below, design guidelines associated with

three general aspects of icon design have been summarized, reflecting key design

questions such as: (1) when should icons be used, (2) what kinds of icons are there,

and (3) what are the key components of an icon?

When should icons be used?

A critical element of icon design is understanding the criteria and issues that should

be considered when determining if an icon is the appropriate element to use to

display an in-vehicle message. Figure 1 (on the following page) shows some

HUMAN CENTERED

SYSTEMS
Figure 1. Examples of the appropriate use of icons.

Figure 2. Types of icons.

Icon Types Key Examples Other Examples

Image-Related

Concept-Related

Arbitrary

Fasten Seat Belt

Flash Function on a camera or

High Voltage symbol in

a power plant.

Addition symbol, First Aid

symbol, or International symbol

for the Red Cross.

Telephone ahead

Curve signs

U.S. Postal Service

Gas station ahead

Elevator

Medical Profession

Icon Design Issue Do This... ...Not This

Quick and accurate

recognition is necessary.

Displaying visual or spatial

concepts.

Presenting a set of

alternatives.

RESTROOMS GASOLINE

 LODGING TELEPHONE
examples of the appropriate use of

icons. Although all icons should be

tested and evaluated before final

implementation into vehicles, icons

should generally be used in place of

text when:

• quick and accurate recognition of

a message is necessary (e.g.,

warnings);

• displaying visual or spatial

concepts (e.g., augmented

signage);

• the driver will be performing a

visual search of alternatives (e.g.,

motorist services information);

• the amount of space on the display

is limited and presenting the

information textually will take up

more space than is available; and

• one already exists and has a

generally accepted meaning.

What types of icons can be used?

Icons can be classified based on their

resemblance to a particular in-vehicle

message or referent. Icons can fall into

one of three categories; examples and

summaries of these three categories are

presented to the left in figure 2.

Importantly, these three different types

of icons have different implications for

icon development and design.

1. Image-related icons are highly

pictorial representations of the

object or act they represent.

Image-related icons are directly

comprehended and should be

used whenever possible.

2. Concept-related icons are based

on an example or property of a

real object or action. Conceptrelated icons can be used if the

user can be expected to be able

to comprehend the context in

which the icon is presented.

3. Arbitrary icons do not resemble the

object or action they represent, but

become meaningful only through

convention and education. Arbitrary icons can be difficult to

recognize, hard to learn, and hard

to remember. They should be

Figure 3. Composition of an icon.

Table 1. Design guidelines for icon components.

Icon Component Human Factors Design Guidelines

Border • Can be used to show the extent of an icon (beginning and end).

Background • Don’t cover more than half the available area with objects.

• Avoid patterns in the background.

• Put the image clearly in front of the background.

• Place objects in the center and the background around the

periphery.

• Use unsaturated, cool colors for the background and saturated,

warm colors for the foreground image.

• Keep the background static; if anything blinks or moves, the

viewer perceives it as a foreground image.

• Limit the background image to a simple rendition of a recognizable,

concrete object.

Element • Use commonly accepted or standardized elements when possible.

• Elements should reflect design principles appropriate for increasing

 icon recognition, such as using the appropriate level of detail

and realism, and incorporating perceptual principles for icon

design.

Symbol • Circles should be used for presenting prohibition on mandatory

(Shapes) information.

• Triangles or diamonds should be used to present warning or

cautionary information.

• Squares or triangles should be used to present general information,

instructions, or safe condition information.

Text Label • Use only when necessary, especially when the icon is conceptrelated or arbitrary.

• Keep text to no more than two-three words.
Issued April 2000 Publication No. FHWA-RD-00-090

Researcher—This study was performed by the Battelle Human Factors Transportation Center, 4000 N.E. 41st Street,

Seattle, Washington 98105. The principle investigator for the contract is John L. Campbell, Ph.D.

Distribution—This technical summary is being distributed according to a standard distribution. Direct distribution is

being made to the Resource Centers, Divisions, and the customers in the automotive industry.

Availability—The guidelines document will be available in the fall of 2001.

Key Words—In-vehicle information systems, icons, symbols, advanced traveler information systems, intelligent

vehicle initiative.

For More Information—Contact Thomas M. Granda, Team Leader, HRDS, (202) 493-3365 or Christopher Monk,

Research Psychologist, SAIC, (202) 493-3382.

Notice—This Announcement is disseminated under the sponsorship of the Department of Transportation in the

interest of information exchange. The Announcement does not establish policies or regulations, nor does it imply

FHWA endorsement of the conclusions or recommendations. The U.S. Government assumes no liability for the

contents or their use.

used only if the user understands

the context in which they will be

presented and also possesses the

specialized knowledge required to

understand them.

What are the different parts of an icon

and how can they be designed to

maximize icon effectiveness?

Icons are complex visual images with a

number of different parts. Through

careful design, these different parts can

work together to increase the likelihood

that the icon will be comprehended by

drivers. Figure 3 summarizes the key

components of an icon; table 1 presents

human factors design guidelines

associated with each component.

Future Guideline

Development Activities

The 36 preliminary guidelines developed so far in this project reflect an

integration of existing empirical studies,

literature reviews and icon design

principles. They represent only a

necessary first step towards the larger

project goal of developing a clear and

comprehensive human factors design

handbook for in-vehicle icons that can

be used throughout the in-vehicle icon

design process. The preliminary guidelines provide both a valuable resource

for icon designers as well as a

“roadmap” that indicates key design

topics for which design guidelines are

needed, but little empirical data exist that

can be used to develop them. The next

phase of this project will involve

conducting a series of empirical studies

that will address critical icon design

issues. The final version of the handbook

will reflect both the results of these

empirical studies, as well as reviews of

the preliminary guidelines conducted by

the project working group and others

from the icon design community.