Technical Report UMTRI-98-4
`
`June, 1998
`
`Map Design: An On-the-Road Evaluation of
`the Time to Read Electronic Navigation Displays
`
`Christopher Nowakowski and Paul Green
`
`umtri
`
`HUMAN FACTORS
`
`FORD EX. 1021
`
`

`

`2. Government Accession No.
`
`1. Report No.
`UMTRI-98-4
`4. Title and Subtitle
`Map Design: An On-the-Road Evaluation of the Time
`to Read Electronic Navigation Displays
`
`Technical Report Documentation Page
`
`3. Recipient’s Catalog No.
`
`5. Report Date
`June, 1998
`6. Performing Organization Code
`account 364781
`8. Performing Organization Report No.
`UMTRI-98-4
`10. Work Unit no. (TRAIS)
`
`11. Contract or Grant No.
`
`13. Type of Report and Period Covered
`5/96 - 6/98
`14. Sponsoring Agency Code
`RCE #939421
`
`7. Author(s)
`Christopher Nowakowski and Paul Green
`9. Performing Organization Name and Address
`The University of Michigan
`Transportation Research Institute (UMTRI)
`2901 Baxter Rd, Ann Arbor, Michigan
`48109-2150 USA
`12. Sponsoring Agency Name and Address
`University of Michigan
`ITS Research Center of Excellence
`200 Engineering Programs Building, 2609 Draper Drive
`Ann Arbor, Michigan 48109 USA
`15. Supplementary Notes
`The ITS Research Center is supported by fees from industrial members and contracts
`from government agencies. Toyota was the primary sponsor for this project.
`16. Abstract
`This report covers the third of four experiments examining the time to read electronic
`maps while driving. Three factors were varied: (1) the number of streets displayed
`(12 street and 24 street maps), (2) the street label text size (10, 12, and 14 point), and
`(3) the time of day (day vs. night driving). Sixteen drivers (ages 18-30 and >65, both
`men and women) drove a test vehicle on public roads. Subjects were given three
`tasks while driving: (1) find the name of the street being driven, (2) find the name of a
`cross street ahead, and (3) find the location of a particular street on the map.
`
`The largest effect was age which increased task response times by 40 to 80%. Each
`additional labeled street increased the response time by 7 to 140 ms depending on
`the task (up to 30%). Using 14 point reduced response time by 200 ms (up to 10%).
`
`Subjective ratings by the drivers revealed uneasiness about their ability to drive
`safely when the task required more than 5 seconds to complete. To avoid this
`discomfort, using 14 point text and no more than 12 labeled streets is recommended.
`
`Further, average response times from on-the-road were within 15% of the mean for
`the same task in a previous simulator experiment. The pattern of results (factors
`significant, their relative impact) were also similar, validating the simulator results.
`17. Key Words
`18. Distribution Statement
`ITS, intelligent transportation systems,
`No restrictions. This document is
`human factors, ergonomics, driving,
`available to the public through the
`electronic maps, navigation systems,
`National Technical Information Service,
`route guidance, driver interface
`Springfield, Virginia 22161
`19. Security Classify. (of this report)
`20. Security Classify. (of this page)
`21. No. of pages
`(None)
`(None)
` 121
`Form DOT F 1700 7 (8-72)
`Reproduction of completed page authorized
`
`22. Price
`
`FORD EX. 1021
`
`

`

`ii
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`FORD EX. 1021
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`

`

`Map Design: An On-the-Road Evaluation
`of the Factors Affecting the
`Time to Read Electronic Maps
`UMTRI Technical Report 98-4
`University of Michigan
`Ann Arbor, Michigan, USA
`Christopher Nowakowski and Paul Green
`
`ISSUES
`
`1
`On-the-Road Evaluation
`1. When do drivers feel that map reading is unsafe while driving?
`2. How many streets should be displayed on an in-vehicle navigation system?
`3. What size text should be used for the street labels?
`4. What is the effect of time of day (day vs. night) on map reading?
`
`Simulator Validation
`1. How do the previous simulator results compare with the on-the-road results?
`
`2
`
`MAP TASKS
`
`Sample Map
`
`Task 1 - On Street
`What street are you on?
`Subject Finds: Edward
`Subject Responds: male M(
`
`key)
`
`Task 2 - Cross Street
`What is the 3rd Cross Street?
`Subject Finds: Suzanne
`( key)
`F
`Responds: female
`What is the 4th Cross Street?
`Subject Finds: only 3 streets
`(
`0
`key)
`Responds: not there
`
`Task 3 - Where is?
`Where is Jonathan?
`Response: behind
`Where is Florence?
`Response: left
`Where is David?
`Response: right
`Where is Albert?
`Response: ahead
`Where is Tammy?
`Response: not there
`
`( )
`
`( )
`
`( )
`
`( )
`
`( )
`0
`
`DAVID
`
`DEBORAH
`
`SUZANNE
`
`EDWARD T
`
`ALBERT
`
`HENRY
`
`JANET
`
`FRANK
`
`FLORENCE
`
`GRACE
`
`HERESA
`
`JONATHAN
`
`Response Keypad
`Task 3 Directional Keys
`right
`ahead
`left
`behind
`0 not there
`Tasks 1 and 2
`Response Keys
`0 not there
`male
`female
`
`0
`
`M F 0
`
`M F
`
`iii
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`

`3
`
`METHOD
`
`Expressway Driving Scenario
`
`Subjects
`Session
`1
`2
`Day
`Night
`Night
`Day
`
`Age 18 - 30
`Men Women
`2
`2
`2
`2
`
`Age >65
`Men Women
`2
`2
`2
`2
`
`Map
`
`Response
`Keypad
`
`Main Test Conditons
`Text Size
`12 Streets 24 Streets
`10 POINT
`12 POINT
`14 POINT
`
`(cid:214) (cid:214)(cid:214) (cid:214)(cid:214) (cid:214)
`
`4
`
`ON-THE-ROAD EVALUATION RESULTS
`
`Cumulative (%)
`
`100
`75
`50
`5
`
`02
`
`Task 2 - Cross Street
`20
`15
`10
`
`x = 3.4 s
`
`05
`
`Frequency (%)
`
`0
`
`5
`10
`15
`Response Time (s)
`
`Mature
`
`Young
`
`Error Rates
`1. Age Effect
`25
`20
`15
`10
`
`Error Rate (%)
`
`05
`
`2
`Task
`2. Number of Streets Effect
`20
`15
`10
`
` 24
`Streets
`
`12 Streets
`
`1
`
`2
`Task
`
`3
`
`05
`
`Error Rate (%)
`
`1
`
`3
`
`Cumulative (%)
`
`100
`80
`60
`40
`0
`
`02
`
`Cumulative (%)
`
`100
`75
`50
`5
`
`02
`
`Task 1 - On Street
`25
`20
`15
`10
`
`Frequency (%)
`
`6
`3
`0
`21
`4 5
`7 8
`Response Time (s)
`
`05
`
`x = 1.8 s
`
`Task 3 - Where is?
`15
`
`x = 5.2 s
`
`10
`
`05
`
`Frequency (%)
`
`0
`
`5
`15
`20
`10
`Response Time (s)
`
`Issue 1 - When is map reading unsafe?
`
`0
`
`5
`1
`8
`6
`4
`2
`3
`7
`Response Time (s)
`
`9
`
`iv
`
`5 4 3 2 1
`
`Very Unsafe
`Unsafe
`Sometimes Unsafe
`Safe
`
`Very Safe
`
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`

`

`Issue 2 - How many streets to display?
`Response time increase
`per each displayed street
`150
`
`10
`
`Task 3 Streets Effect
`
`Mature
`
`Recommendation:
`
`Display £12 Streets
`
`Young
`
`24
`12
`Streets displayed
`
`2468
`
`(s)
`
`1
`
`2
`Task
`
`3
`
`100
`(ms)
`
`50
`
`0
`
`Issue 3 - What text size to use?
`Task 1 Point Size Effect
`2.0
`1.9
`1.8
`1.7
`1.6
`1.5
`
`24 st.
`
`Task 2 Point Size Effect
`4.5
`4.0
`3.5
`3.0
`2.5
`
`12 st.
`
`10
`
`12
`Point Size
`
`14
`
`Recommendations:
`
`1. When possible,
` Use 14 point.
`
`2. Do not use <12 point
`
`(s)
`
`24 st.
`
`(s)
`
`12 st.
`
`10
`
`12
`Point Size
`
`14
`
`Issue 4 - Day/Night Effects
`Task 1 - Night learning
` is more difficult
`
`Task 3 - Night increases
` response time
`
`(s)
`
`2.1
`2.0
`1.9
`1.8
`1.7
`1.6
`
`(s)
`
`6.0
`5.5
`5.0
`4.5
`4.0
`Night
`Day
`
`1
`
`Session
`
`2
`
`1
`
`2
`
`Session
`
`Recommendation:
`
`Issues of color,
`luminance, and contrast
`for night-use maps
`need to be addressed
`in further reasearch.
`
`Response Time Regression Equations (ms)
`RT = 6710 + 325*(A) + 6.67*(S) + 33.75*(P)2 - 832.50*(P)
`Task 1 - On Street
`+ 9.58*(C)
`
`Task 2 - Cross Street
`
`RT = 1210 + 575*(A) + 370*(X) + 40.83*(S)
`+ 8.08*(P-12)*(SL)+ 40.83*(S-12)*[MINIMUM(1,X-2)]
`
`Task 3 - Where is?
`
`RT = [1630 + 1235*(A) + 380*(T) + 136*(S) + 27*(A)*(SL)
`+ 475*(L)]*(SR)
`
`v
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`

`

`Regression Equations Terms
`-1 if young
`{
`A = Age
`+1 if mature
`S = Number of streets (S ‡ 1)
`P = Point size (10 £ P £14)
`0 if £ 12 point
`{
`(P-12)(S-12.52) if > 12 pt.
`-1*(24-S) if S £ 12
`+1*(S-12) if S > 12
`
`SL = Street level
`
`{
`
`C = Clutter
`
`T = Time of day
`
`-1 for day
`{
`+1 for night
`X = Target cross street (X ‡ 1)
` -1 if ahead
`{
` 0 if not there
`+1 if behind, left or right
`
`L = Target location
`
`SR = Search result
`
`{
`
`1 if found
`1.70 if not found
`
`5
`
`SIMULATOR VALIDATION RESULTS
`
`Subjects
`
`Experiment
`
`Simulator
`On-the-Road
`
`Age 65<
`Age 18 - 30
`Men
`Women Men Women
`5
`5
`5
`5
`4
`4
`4
`4
`
`Trials per Subject
`Task 1
`Task 3
`6
`24
`24
`48
`
`Response Time Comparison
`Task 1 - On Street
`
`Cumulative (%)
`
`100
`75
`50
`25
`0
`75
`50
`25
`0
`
`Task 3 - Where is?
`
`Simulator
`x = 5.96 s
`
`On-the-Road
`x = 5.20 s
`
`0
`
`20
`15
`10
`5
`Response Time (s)
`
`246
`
`0246
`
`Frequency (%)
`
`Cumulative (%)
`
`100
`75
`50
`25
`0
`75
`50
`25
`0
`
`Simulator
`x = 1.64 s
`
`On-the-Road
`x = 1.79 s
`
`0
`
`4
`3
`2
`1
`Response Time (s)
`
`5
`
`20
`15
`10
`
`05
`
`15
`10
`
`05
`
`Frequency (%)
`
`Conclusions:
`The optimal point size
`was also dependent
`upon the display
`resolution and location
`(character visual angle).
`
`Differences in Experimental Findings
`Task 1 - Point Size Effects
`Task 3 - Point Size Effects
`2500
`7000
`
`Simulator
`
`6000
`
`5000
`
`4000
`
`(ms)
`
`On-the-Road
`
`Simulator
`
`10
`
`12
`Point Size
`
`14
`
`2000
`
`1500
`
`1000
`
`(ms)
`
`On-the-Road
`
`10
`
`12
`14
`Point Size
`
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`

`

`PREFACE
`
`This research was funded by the University of Michigan Intelligent Transportation
`Systems (ITS) Research Center for Excellence, formerly the IVHS Research Center for
`Excellence. The program is a consortium of companies and government agencies,
`working with the University, whose goal is to advance ITS research and
`implementation.
`
`The current sponsors are:
`
`• Ann Arbor Transit Authority
`• Automobile Association of America (AAA)
`• Chrysler Corporation
`• Federal Highway Administration (FHWA)
`• Ford Motor Company
`• General Motors Corporation
`• Hewlett Packard
`• Michigan Department of Transportation
`• Nissan Motors
`• NOVA Laboratories
`• Orbital Sciences
`• Road Commission of Oakland County
`• Ryder Trucks
`• Siemens Automotive
`• Toyota Motor Corporation
`
`We would like to thank the lead corporate sponsor for this project, Toyota Motor
`Corporation, for their support. Originally Cale Hodder, and now Jim Bauer (both from
`Toyota), have served as project technical monitors.
`
`Electronic maps are commonplace in automotive navigation systems in Japan, and
`soon will be common in the U.S. and Europe. To make such maps safe and easy to
`use while driving, it is important to know how engineering, individual, and task factors
`affect reading time, and how reading time can be minimized. The more time drivers
`spend looking in the vehicle, the less time they spend looking at the road, increasing
`the opportunity for crashes. Given the almost complete absence of literature on the
`time to read maps prior to this project, two specific issues were addressed.
`
`Issue 1: How long does it take to read an electronic local map as a function of label
`size and orientation, the number of streets shown, the percentage of streets
`labeled, display location, and the driver's task?
`
`Issue 2: When do drivers desire area maps instead of turn (intersection) displays?
`
`These issues were examined in 5 reports summarized on the next page:
`
`vii
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`

`Green, P. (1998). Reading Electronic Area Maps: An Annotated Bibliography ,
`(Technical Report UMTRI-98-38).
`
`This report contains a collection of abstracts generated by the author.
`Primary articles concerned performance differences in reading street
`names due to font, how people follow directions using street maps, etc.
`There were no articles in the literature that methodically considered how
`factors related to street map design affect task completion time.
`Secondary articles considered color coding, symbols for tourist
`information, etc.
`
`Authors to be determined (1998). Preliminary Examinations of the Time to Read
`Electronic Maps: The Effects of Text and Graphic Characteristics , (Technical Report
`UMTRI-98-36).
`
`This report summarizes the initial series of simulator experiments
`concerning reading electronic maps. Included were efforts to identify
`representative maps and street names for testing and a pilot experiment
`concerning the subjective legibility of various map typefaces. In the main
`experiment, the time to read the electronic maps was found as a function
`of text size, the number of streets, text orientation, and grid-likeness.
`
`Brooks, A. and Green, P. (1998). Map Design: A Simulator Evaluation of the Factors
`Affecting the Time to Read Electronic Navigation Displays , (Technical Report
`UMTRI-98-7).
`
`This report describes a simulator experiment that was an extension of the
`first main experiment. This extension examined situations when only
`some of the street names were labeled, small text sizes, and the effect of
`map location in the vehicle.
`
`Nowakowski, C. and Green, P. (1998). Map Design: An On-the-Road Evaluation of the
`Time to Read Electronic Navigation Displays , (Technical Report UMTRI-98-4).
`
`This report summarizes an on-the-road study that was run in parallel with
`the previous report and examined similar factors. The same text sizes
`and number of streets were used, but all the streets were labeled and the
`effect of day and night was studied. These results were used to bridge
`the laboratory results to real, on-the-road situations.
`
`Brooks, A., Nowakowski, C., and Green, P. (1998). Turn-by-Turn Displays versus
`Electronic Maps: An On-the-Road Comparison of Driver Glance Behavior , (Technical
`Report UMTRI-98-37).
`
`This report describes an on-the-road study that examined when and how
`often drivers look at turn-by-turn and electronic map displays in route
`guidance. Factors examined included road type (residential, freeway,
`etc.) and the distance to the next turn/decision point.
`
`viii
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`

`TABLE OF CONTENTS
`
`INTRODUCTION ........................................................................................1
`Overview..............................................................................................................................1
`Issues....................................................................................................................................2
`
`TEST PLAN ...............................................................................................5
`Test Participants..............................................................................................................5
`Test Activities and Their Sequence .......................................................................5
`Map Construction ............................................................................................................7
`Task Descriptions ...........................................................................................................7
`Practice 1: Keypad Practice (Male and Female) .....................................7
`Task 1: What Street Are You On? ....................................................................8
`Task 2: What Is the nth Cross Street? ..........................................................9
`Practice 2: Keypad Practice (Arrow Keys)................................................10
`Task 3: Where Is the Target Street?............................................................11
`Test Vehicle .....................................................................................................................11
`Test Route.........................................................................................................................14
`
`RESULTS................................................................................................17
`Data Reduction...............................................................................................................17
`
`Task 1: What Street Are You On? ........................................................................18
`Errors ...........................................................................................................................18
`Response Time........................................................................................................18
`Subject Effects (Age and Gender)....................................................................19
`Context Effects (Road, Time of Day, and Map Template).............................20
`Map Design Effects (Number of Streets and Point Size)..............................20
`Task 1 Response Time Prediction Model ...................................................21
`Driving Performance.............................................................................................22
`
`Task 2: What Is the nth Cross Street? ...............................................................22
`Errors ...........................................................................................................................22
`Subject Effects (Age and Gender)....................................................................22
`Context Effects......................................................................................................24
`Map Design Effects..............................................................................................24
`Response Time........................................................................................................25
`Subject Effects (Age and Gender)....................................................................26
`Context Effects (Road, Session, and Time of Day)........................................26
`Map Design Effects (Condition and Point Size).............................................27
`Task 2 Response Time Prediction Model ...................................................28
`Driving Performance.............................................................................................29
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`Task 3: Where Is the Target Street?...................................................................31
`Errors ...........................................................................................................................31
`Factors Influencing Error Rate...........................................................................33
`Response Time........................................................................................................34
`Subject Effects (Age and Gender)....................................................................35
`Context Effects (Road, Time of Day, and Response Location)....................36
`Map Design Effects (Number of Streets and Point Size).............................37
`Task 3 Response Time Prediction Model ...................................................38
`Driving Performance.............................................................................................39
`
`Subjective Task Ratings ............................................................................................41
`Driver Eye Movements................................................................................................43
`
`CONCLUSIONS.......................................................................................45
`
`SIMULATOR VALIDATION.......................................................................49
`Validation Method .........................................................................................................49
`
`Validation Results .........................................................................................................49
`Task 1: What Street Are You On? .................................................................49
`Context Effects......................................................................................................51
`Subject Effects......................................................................................................51
`Map Design Effects..............................................................................................52
`Task 3: Where is the Target Street?............................................................54
`Context Effects......................................................................................................56
`Subject Effects......................................................................................................57
`Map Design Effects..............................................................................................57
`
`Simulator Validation Conclusions ........................................................................59
`
`REFERENCES.........................................................................................61
`
`APPENDIX A - Participant Consent Forms..............................................63
`APPENDIX B - Subject Biographical Form..............................................65
`APPENDIX C - Instructions to Subjects...................................................67
`APPENDIX D - Map Examples.................................................................75
`APPENDIX E - Experimental Conditions by Task....................................81
`APPENDIX F - Test Vehicle Illustrations.................................................87
`APPENDIX G - Test Routes......................................................................89
`APPENDIX H - Listing of Invalid Trials and Outliers by Task..................93
`APPENDIX I
`- Lane Crossing Benchmark Images..................................95
`APPENDIX J - Table of Task 1 Error Trials.............................................97
`APPENDIX K - Task 1 Response Time ANOVA Table..............................99
`APPENDIX L - Task 2 Response Time ANOVA Table............................101
`APPENDIX M- Task 3 Error ANOVA Table............................................103
`APPENDIX N - Task 3 Response Time ANOVA Table............................105
`APPENDIX O - Simulator Validation Task 1 ANOVA Table ...................107
`APPENDIX P - Comparison of Display Positions ..................................109
`APPENDIX Q - Simulator Validation Task 3 ANOVA Table ...................111
`
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`

`Introduction
`
`Overview
`
`INTRODUCTION
`
`Recently there has been an influx of in-vehicle navigation systems into the United
`States, both as standard equipment (on the Acura RL and several Lexus vehicles) and
`as aftermarket products such as the Rockwell (now Magellan) PathMaster, the Alpine
`voice navigation system, and the Philips (now VDO) Carin system. A major concern is
`that the in-vehicle maps provided by navigation systems may be difficult to read,
`distracting drivers from attending to the road ahead. Such distractions could provide
`increased opportunities for crashes (Green, 1997) as is suspected for cellular phones
`(Goodman, Bents, Tijerina, Wierwille, Lerner, and Benel, 1997).
`
`In recognition of this safety concern, Paul Green is developing a Society of Automotive
`Engineers (SAE) standard, a precursor to an International Standards Organization
`(ISO) standard, on what drivers should be permitted to do with a navigation system
`while a vehicle is in motion. Of considerable value in developing such a standard
`would be baseline data on how long it takes to read a map as a function of its content
`and the task to be completed. Accordingly, this project is a timely coincidence.
`
`There have been numerous studies concerning matters relating to human factors and
`the design of navigation displays. (See Green, 1992 for a review.) Almost all of the
`prior research has considered issues relating to the modality to be used for navigation
`information and attentional demands of particular implementations (Dingus, McGehee,
`Hulse, Jahns, Manakkal, Mollenhauer, and Fleischman, 1995; Green, Hoekstra, and
`Williams, 1993; Green, Williams, Hoekstra, George, and Wen, 1993), not the impact of
`specific map characteristics such as is addressed by this series of experiments.
`Therefore, this project breaks new ground.
`
`The first report of this project was an annotated bibliography of the research on
`reading electronic area maps (Green, 1998). The report verified the a priori notion that
`relevant literature was limited. The vast majority of studies concern how colors should
`be assigned to areas on a map (states or provinces) so no two adjacent areas have
`the same color.
`
`Several significant pilot studies were conducted as part of the first experiment. Those
`studies identified typical content of electronic maps (number of streets, street name
`length, etc. for the United States) and developed a task set representative of what
`drivers do. The first major laboratory experiment, conducted in a driving simulator,
`examined the time to read electronic maps as a function of numerous map display
`factors (Green, 1998). A total of 20 drivers (10 under 30 years of age and 10 over 65
`years of age) operated a driving simulator while performing one of three tasks: (1)
`identifying the street being driven, (2) identifying a particular cross street, or (3)
`locating a particular street on a map. These same three representative tasks have
`been used consistently in this project. Further, they are interesting experimentally as
`they vary in complexity and completion time.
`
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`

`

`Introduction
`
`Variables examined in the first experiment included: (1) the number of streets shown
`(6 through 36), (2) label point size (12 and 18 point), (3) the street configuration (grid
`verses nongrid), and (4) the street label orientation (horizontal, vertical, and vertical
`stacked).
`
`The results were that the response times increased as the number of streets shown
`increased. For the label size, the reading time for 18 point text was significantly slower
`(by 11 percent) than for 12 point, especially with a large number of streets on the map.
`Large point sizes combined with many visible streets created a cluttered map which
`dramatically increased the drivers’ response times. Additionally, drivers were able to
`read the maps faster when the maps were based on a grid layout, rather than a less
`structured, more random arrangement. The regularity of the grid facilitated search.
`Finally, the best label orientations were horizontal for horizontal streets and vertical for
`vertical streets, even though horizontal text is normally easier to read. In this case, the
`vertical text facilitated the association of each label with a particular line representing a
`street.
`
`Following the initial laboratory experiment, a second laboratory experiment was
`conducted in parallel with this on-the-road study to reexamine some of the map
`display factors (Brooks and Green, 1998). Using the same three tasks as the first
`experiment, the variables examined in the second experiment included: (1) the
`number of streets (12 through 36), (2) label point size (10, 12, and 14 point), (3)
`percentage of streets labeled (33, 66, 100 percent), (4) display location (high or low on
`the center console).
`
`The results of the second laboratory experiment showed that labeled streets increased
`the response times more than the unlabeled streets for most of the tasks, and a
`maximum of 12 labeled streets should be used on the map to optimize search
`performance. The experiment also found that the use of 10 point text increased the
`response times for all tasks, especially for older drivers. In general 14 point text was
`preferred, although clutter effects were seen when using that point size on maps
`containing more than 16 labeled streets. The effect of display location was only tested
`using the first task, identify the street being driven. The higher location produced
`slightly faster response times (by 10 percent).
`
`Issues
`
`All of the initial work was conducted in a driving simulator to provide consistent test
`conditions and reduce cost. However, once the relationships of the key factors were
`established, it was necessary to determine the necessary adjustment of the laboratory
`data to predict on-the-road performance. Consequently, some of the test conditions
`from the previous simulator study (plus some additional conditions of interest) were
`explored on the road.
`
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`Introduction
`
`There were four key issues:
`
`1. When do drivers feel that map reading is unsafe while driving?
`
`Maps should not be so complex that they require an excessively long time to read. The
`major concern is that if drivers are not looking at the road, the risk of a crash increases.
`Prior to this research, there was a minimum of data on what drivers thought to be
`excessive. (See Hada, 1994 as an example.) One way to determine when drivers
`began to feel uncomfortable was to ask them to rate the tasks on a scale with regard to
`interference with driving and perceived safety.
`
`2. What size text and how many streets should be displayed?
`
`The first experiment tested only 12- and 18-point text sizes for street names, both of
`which are larger than the text used in some U.S. navigation systems. Unresolved was
`the impact of smaller font sizes on map reading times. Since the first experiment
`showed a large street’s effect and an interaction between streets and text size, the
`number of streets displayed was also included as a factor in the on-the-road
`experiment.
`
`3. How does the ambient lighting (time of day) affect map reading?
`
`Altering the ambient light changes both the display contrast and its overall luminance
`level. The lighting levels in the UMTRI simulator approximated dusk. Although some
`adjustments can be made, limits of the scene projector output make simulating a wide
`range of conditions, especially daylight, difficult. (This is true of all driving simulators of
`which the authors are aware.) Accordingly, on-road driving was used to examine the
`effects of ambient lighting. Readers should remember that changes in scene
`luminance and interior illumination occur together, and furthermore, day-night
`differences were accompanied by changes in traffic volume.
`
`4. How do the simulator results compare with the on-the-road results?
`
`Experiments were conducted, for the most part, in the driving simulator because the
`conditions could be well controlled, especially traffic, leading to more stable results.
`Further, Michigan winters made collecting on-the-road data impossible. Rain in the
`spring and fall can likewise be problematic leading to schedule delays. Since the data
`was collected to predict on-the-road performance, differences between the two
`contexts were examined experimentally by replicating a subset of the test conditions
`from the driving-simulator experiment in the on-the-road experiment.
`
`As an aside, the fourth experiment, which is in the planning stages as this report is
`being written, will consider when drivers want maps and when turn displays should be
`provided. The rationale is that for reasons of space and cost, only a single display
`may be available. The ideal situation would be for the navigation computer to "know"
`at any given moment which display format a driver might desire, and automatically
`present it, rather that forcing a driver to press a key each time a different format display
`should appear.
`
`3
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`4
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`FORD EX. 1021
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`Test Plan
`
`Test Participants
`
`TEST PLAN
`
`A total of 16 licensed drivers (8 men and 8 women equally drawn from two age
`groups) participated in the experiment. The subjects were randomly selected from the
`UMTRI human factors subject database of past subjects, friends of the staff, and those
`recruited through newspaper advertisements. Only those who had not participated in
`a previous map study or any other recent UMTRI study were recruited. Subjects were
`tested on one of two roads, M-14 or I-94, and in one of two time sequences, either day
`before night or night before day, with a minimum of three days between sessions.
`(See Table 1.) The eight subjects tested on M-14 were each paid $20 for each
`session with a bonus of $15 for completing both sessions. The I-94 subjects were paid
`an extra $10 paid to compensate for the longer drive to the test site. Three additional
`subjects were tested on M-14 but discarded to preserve a balanced design after the
`unexpected start of road construction required relocation of the test site.
`
`Table 1. Subjects.
`
`Road
`
`M-14
`
`I-94
`
`Time Sequence
`(session 1, 2)
`
`Day, night
`Night, day
`Day, night
`Night, day
`
`Young (19 - 25)
`(mean=22)
`Men
`Women
`1
`1
`1
`1
`1
`1
`1
`1
`
`Mature (65 - 75)
`(mean=68)
`Men
`Women
`1
`1
`1
`1
`1
`1
`1
`1
`
`Corrected visual acuity over all subjects ranged from 20/15 to 20/100 with means of
`20/18 for younger subjects and 20/37 for older subjects. Seventy-five percent of the
`subjects wore either glasses or contacts.
`
`Subjects drove an average of 12,000 miles per year with no differences due to age or
`gender. Only one subject had seen or used an in-vehicle navigation system, having
`participated in an on-road study of a navigation system four years ago (Green,
`Williams, Hoekstra, George, and Wen, 1993). Subjects reported, on average, that they
`had used maps 3 to 4 times over the past 6 months and that their computer use was
`daily, except for a few older subjects whose computer use was infrequent or never.
`
`Test Activities and Their Sequence
`
`Each subject began by completing a consent form (Appendix A), a biographical form
`(Appendix B), and having their vision checked. See Appendix C for the complete
`instructions to subjects.
`
`Each experimental session consisted of two practice tasks and three experimental
`tasks. (See Table 2.) During each 8-minute, 24-trial sequence, subjects drove
`approximately 8 miles. An example or two of each task was shown to the subject
`before the start of the experiment while pa