General Development Procedures for In- Vehicle Icons John L. Campbell Battelle Human Factors Transportation Center Seattle, Washington May 22, 2003 ITS

General Development Procedures for In-Vehicle Icons

John L. Campbell

Battelle Human Factors Transportation Center

Seattle, Washington

May 22, 2003ITS AMERICA

May, 2003

2

Discussion Topics

Overview of Icon Project

Review of Icon Design Guidelines

Icon Project Summary

3

Overview of Icon Project3 Project Phases

Analytical: Review current in-vehicle icon use and designer needs for human factors

information for in-vehicle icons.

Empirical: Conduct experiments to address high-priority research gaps in the icon design literature.

Integrative: Develop both preliminary and final human factors design guidelines for in-vehicle icons.

4

Overview of Icon Project Working Group: Role in the Project

Participate in regular teleconferences to discuss project status, deliverables, and future plans

Review project reports and provide feedback Provide relevant information and documents to the

project team Identify the needed content, organization, and

format for the guidelines Serve as reviewers for the in-progress guidelines Provide more formal evaluation of draft guidelines

handbook and IDEA software tool

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Review of Icon Design Guidelines Specific Goals for the Icon Design Guidelines Relevant to a range of in-vehicle devices and

applications. Clear and understandable to automotive designers with

different backgrounds and HF knowledge. Easy-to use during the entire icon development process. Identify when to use in-vehicle icons. Design aid and resource for the development and evaluation

of new symbols.

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Review of Icon Design GuidelinesSummary of Icon Design Handbook

Chapter 2: General Issues in Icon Design (6 Guidelines)Chapter 3: Icon Legibility (5 Guidelines)Chapter 4: Icon Recognition (6 Guidelines)Chapter 5: Icon Interpretation (8 Guidelines)Chapter 6: The Auditory Presentation of In-Vehicle

Information (11 Guidelines)Chapter 7: Evaluating In-Vehicle Icons (6 Guidelines)Chapter 8: Icon Collection (Candidate/Sample Icons for

>400 IVIS messages)

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Review of Icon Design Guidelines General Presentation Format

DETERMINING THE APPROPRIATE LUMINANCE UNIFORMITY WITHIN AN ICON

Introduction: Luminance uniformity refers to the consistency of luminance values across an icon. Moderate


Introduction:nonuniformities in luminance may only lead to the perception, by the driver, that the display is of poor quality. With great nonuniformities in luminance, however, drivers may not be provided with sufficient luminance andContrast to ensure adequate legibility in certain areas of the display.

Icon Design Guidelines ICON LEGIBILITY May 17, 1999 Icon Design Guidelines ICON LEGIBILITY May 17, 1999

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Right-hand page

References

CrossReferences

DesignIssues

Discussion

AbbreviatedHandbook Title(Both Pages)

AbbreviatedChapter Title(Both Pages)

Revision Date(Both Pages)Guideline Title Bar Scale Rating

Introduction

DesignGuideline

References:1. Mueller, C. G. (1951). Frequency of seeing functions for intensity discrimination at various levels of

adapting intensity. Journal of General Psychology, 34, 463-474.2. Boff, K. R., Kaufman, L., & Thomas, J. P. (1986). Handbook of perception and human performance. New

York: J. Wiley & Sons.3. Farrell, R. J., & Booth, J. M. (1984). Design handbook for imagery interpretation equipment. Seattle,

WA: Boeing Aerospace Company.4. American National Standards Institute. (1988). American national standard for human factors engineering

of visual display workstations. Santa Monica, CA: Human Factors and Ergonomics Society.5. MIL-STD-1472D. (1989). Human engineering design criteria for military systems, equipment and

facilities. Washington, DC: U.S. Government Printing Office.

Discussion: Threshold Luminance Discrimination Data. Although observers in Reference 1 could discriminate lights that differed in luminance by as little as 10 percent, these data were obtained when they were trying to detect a luminance difference between a background and a target under ideal laboratory conditions (see Reference 2 also). Thus, 10 percent represents a threshold luminance discrimination value and is far too conservative for IVIS use, in which the issue of concern is the driver's ability to notice luminance differences under normal driving or normal viewing conditions.

Tolerance for Luminance Variations. Reference 3 indicates that luminance in cathode ray tubes (CRTs) typically varies by as much as 37 percent and is either not noticed or is considered to be acceptable by observers. Reference 4 recommends that luminance variations remain below 50 percent. Reference 5 indicates that while the preferred limit for luminance variation across optical projection displays is 33 percent, an unacceptable limit is 66 percent.

Conclusions. The design objectives provided above reflect a composite of the information provided by References 3, 4, and 5. Specifically, if luminance differences up to 37 percent are not always noticed by observers and if 33 percent represents a preferred limit, then 33 percent seems to be an acceptable limit for small-area luminance nonuniformities (i.e., within an individual element or segment). Both 50 percent and 66 percent have been suggested as absolute upper limits on luminance nonuniformities.

Design Issues: Causes. Luminance nonuniformities are generally caused by the display itself. In vacuum fluorescent displays (VFDs) being viewed directly, for example, these might be caused by poor phosphor distribution on the inside of the anodes, or by fluctuations in the power supply output.

Cross References:Determining the Appropriate Contrast within an Icon, p. 3-4

Measuring Luminance Nonuniformity

Luminance A Luminance B

Within a segment or element of an icon, measure at twolocations using a photometer with a spot size small

enough to fit inside the segment or element.

% ElementNonuniformity

= |(Luminance min) - (Luminance max)|

(Luminance max)(Eq. 1)

Where: Luminance min= the smaller luminance valueLuminance max= the greater luminance value

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Left-hand pagePage Numbers

Figure,Table, orGraphic

Design Guidelines

Provide no more than 33% Element Nonuniformity (within an individual element or segment).

Design Guidelines

Based Equally on Expert Judgmentand Experimental Data

Based Primarily onExperimental Data

Based Primarily onExpert Judgment


Introduction: Luminance uniformity refers to the consistency of luminance values across an icon. Moderate


Introduction:nonuniformities in luminance may only lead to the perception, by the driver, that the display is of poor quality. With great nonuniformities in luminance, however, drivers may not be provided with sufficient luminance andContrast to ensure adequate legibility in certain areas of the display.

Icon Design Guidelines ICON LEGIBILITY May 17, 1999 Icon Design Guidelines ICON LEGIBILITY May 17, 1999

3-3

Right-hand page

References

CrossReferences

DesignIssues

Discussion

AbbreviatedHandbook Title(Both Pages)

AbbreviatedChapter Title(Both Pages)

Revision Date(Both Pages)Guideline Title Bar Scale Rating

Introduction

DesignGuideline

References:1. Mueller, C. G. (1951). Frequency of seeing functions for intensity discrimination at various levels of

adapting intensity. Journal of General Psychology, 34, 463-474.2. Boff, K. R., Kaufman, L., & Thomas, J. P. (1986). Handbook of perception and human performance. New

York: J. Wiley & Sons.3. Farrell, R. J., & Booth, J. M. (1984). Design handbook for imagery interpretation equipment. Seattle,

WA: Boeing Aerospace Company.4. American National Standards Institute. (1988). American national standard for human factors engineering

of visual display workstations. Santa Monica, CA: Human Factors and Ergonomics Society.5. MIL-STD-1472D. (1989). Human engineering design criteria for military systems, equipment and

facilities. Washington, DC: U.S. Government Printing Office.

Discussion: Threshold Luminance Discrimination Data. Although observers in Reference 1 could discriminate lights that differed in luminance by as little as 10 percent, these data were obtained when they were trying to detect a luminance difference between a background and a target under ideal laboratory conditions (see Reference 2 also). Thus, 10 percent represents a threshold luminance discrimination value and is far too conservative for IVIS use, in which the issue of concern is the driver's ability to notice luminance differences under normal driving or normal viewing conditions.

Tolerance for Luminance Variations. Reference 3 indicates that luminance in cathode ray tubes (CRTs) typically varies by as much as 37 percent and is either not noticed or is considered to be acceptable by observers. Reference 4 recommends that luminance variations remain below 50 percent. Reference 5 indicates that while the preferred limit for luminance variation across optical projection displays is 33 percent, an unacceptable limit is 66 percent.

Conclusions. The design objectives provided above reflect a composite of the information provided by References 3, 4, and 5. Specifically, if luminance differences up to 37 percent are not always noticed by observers and if 33 percent represents a preferred limit, then 33 percent seems to be an acceptable limit for small-area luminance nonuniformities (i.e., within an individual element or segment). Both 50 percent and 66 percent have been suggested as absolute upper limits on luminance nonuniformities.

Design Issues: Causes. Luminance nonuniformities are generally caused by the display itself. In vacuum fluorescent displays (VFDs) being viewed directly, for example, these might be caused by poor phosphor distribution on the inside of the anodes, or by fluctuations in the power supply output.

Cross References:Determining the Appropriate Contrast within an Icon, p. 3-4

Measuring Luminance Nonuniformity

Luminance A Luminance B














(Luminance max)

|(Luminance min) - (Luminance max)|



3-2

Left-hand pagePage Numbers

Figure,Table, orGraphic

Design Guidelines


Design Guidelines




Design Guidelines


Design Guidelines




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Icon Legibility Sample Guideline: Designing Effective Text Labels

Low Clearance Ahead

Effective Use of Text Label

Overheight vehicles takeanother route aroundrestricted clearance.

Ineffective Use of Text Label

Use both uppercase andlowercase letters.

Avoid using italicsto emphasize words.

The space between lines should beat least 1/30 the line length.

Make the type >0.27 degreesvisual angle.

Use a clear andsimple font.

Keep text labels brief - use no more than 2 to 3 words.

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Icon RecognitionSample Guideline: Perceptual Principles of Icon Design

Icon Design Parameter Recommendation Do This… …Not This

Figure/Ground Relationship Emphasize a clear, stable, and solid relationship between the elements of the symbol and its background.

Figure Edges Relatively solid shapes are better than thin or dotted-line edges unless the element in question depicts action or movement.

Closure Use closed figures without discontinuous lines, outlines, or disjointed elements that can result in a fragmented figure.

Simplicity Icons should be simple with only the necessary detail included. Removal of these details should result in low recognition.

Unity All parts of the symbol should be enclosed within a single boundary

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Icon InterpretationSample Guideline: Identifying Icons as Part of a Group

DESCRIPTION EXAMPLE

Common boundary identifies agroup of icons as conveyingwarning information.

Icons identified by a common levelof detail and abstraction.

Icons identified by a commonstyle.

Icons grouped by border,background, color, and style.

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Auditory Presentation of In-Vehicle InformationSample Guideline: Determining the Appropriate Auditory Signal

FUNCTIONS EXAMPLE MESSAGE SIMPLE TONES EARCONS AUDITORY

ICONSSPEECH

MESSAGES

Status Indication Navigation system on and functioning Good Good Fair Poor

Alerting (Attentional)

Generic warning indicator (to divert attention to a display)

Good Fair Poor Poor

Warning (Informational)

Rear-end collision avoidance warning indicator

Fair Poor Good Fair

Presentation of Qualitative Information

Location of next available lodging Poor Poor Poor Good

Presentation of Quantitative Information

Cost of upcoming toll bridge Poor Poor Poor-Fair Good

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Evaluation of GuidelinesSample Guideline: Overview of Evaluation Procedures

Are candidateicons developedand/or in use?

(see Chapter 8)

PoorResponse?

Conduct Comprehension/Recognition Tests (see page 7-8)

• Prepare Test Materials• Provide Subjects with Instruction• Test Candidate Symbols with a Representa-

tive Group of Subjects• Analyze Data• Interpret Results




Conduct Appropriateness Ranking Tests (see page 7-6)

• Reproduce Production Test Icons• Randomize Presentation Order to Test Icons• Rank Order Test Icons• Calculate Scale Values• Select Candidates for Further Study



Use Production Test to Generate Ideas for Icon (see page 7-4)

• Identify Messages for Icons• Generate Candidate Symbols/Icons• Evaluate Candidate Symbols/Icons• Identify Candidate Icons for Further Testing



Testing may be complete. As necessary, Re-design Icons and Repeat Evaluations.

Consider alternate approaches to evaluations (see page 7-12).



Conduct Matching Tests (see page 7-10)• Prepare Test Materials• Provide Instructions to Subjects• Conduct Test• Analyze Data• Interpret Results


Yes

No

No Yes

Conduct analyses to determine that the iconsconform to design principles and guidelines for:

• Legibility (see Chapter 3)

• Recognizability (see Chapter 4)

• Interpretability (see Chapter 5)





Testing may be complete. Proceed as necessary.


Are candidateicons developedand/or in use?

(see Chapter 8)

PoorResponse?





















Yes

No

No Yes











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Icon IDEA: Icon Development and Evaluation Assistant

A searchable database of 431 icons, organized by specific in-vehicle system functions and subfunctions,

Evaluation scores for each of the icons in the database that reflect critical human factors design characteristics of the icons,

Recommendations for improving the design of icons evaluated by the IDEA tool,

Comprehension ratings from 160 experimental subjects for a subset of the icons, and

The ability to add and evaluate new icons.

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Icon Project Summary

Key Products• Icon Design Guidelines

• IDEA Software Tool

• Icon Testing Procedures for SAE & ISO

Documents

General Development Procedures for In- Vehicle Icons John L. Campbell Battelle Human Factors Transportation Center Seattle, Washington May 22, 2003 ITS