Conspicuity of motorcycles in traffic:

Evidence from change-blindness experiments

1

2

3

Introduction

1981*

*Hurt, Ouellet, & Thom (1981)4

35%

65%

Motorcycle Collisions: Multiple Vehicles

Other

Right-of-WayViolation

26%

74%

Motorcycle Collision Types

Single VehicleCollision

Multiple VehicleCollision

Typical Right-of-Way Violation

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Introduction

Common belief: Collisions are due to conspicuityMotorcycles are difficult to detect because they are small

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Countermeasures:Daytime running lights

Introduction

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ThenNow

Introduction

Countermeasures:Headlight modulators

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ThenNow

Introduction

Countermeasures:Fluorescent jackets

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ThenNow

Does enhanced conspicuity reduce collisions?

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Does enhanced conspicuity reduce collisions?

*ACEM (2009)

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35%

65%

1981

28%

72%

2009*

Other

Failure to Seethe Motorcycle

20%

80%

2009*

SingleVehicleCollision

MultipleVehicleCollision

26%

74%

1981

Motorcycle Collision TypesMotorcycle Collisions: Multiple Vehicles

Introduction

If motorcycle collisions are due to poor conspicuity,

And if we have improved motorcycle conspicuity,

Then why have failure-to-see collisions increased?

Are these collisions really due to poor conspicuity?

Are motorcycles even inconspicuous?

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Change-Blindness

Are motorcycles less conspicuous than cars?

Demo

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Are motorcycles less conspicuous than cars?

Change Blindness is a measure of attention

We notice changes for attended objects

Change-Blindness

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Static Change-Blindness

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Static Change-Blindness

1895% Confidence Interval

Are motorcycles detected less frequently than cars?

Sager et al. (In Review)

Static Change-Blindness

Detection times

1995% Confidence Interval

1

3

5

7

9

11

Car Motorcycle

Re

acti

on

Tim

e (

s)

Static Change-Blindness: Discussion

Motorcycles are visible:

Higher detection rates than cars

Similar detection times to cars

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Contrast

Saliency (Sensory Conspicuity)

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Orientation

Saliency (sensory conspicuity)

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Spatial Frequency

Saliency (sensory conspicuity)

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Colour

Saliency (sensory conspicuity)

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Static Change-Blindness

Saliency maps and Gaze Maps

Perception is More than Sensation

Context

Intention

Memory

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Static Change-Blindness

Car and Motorcycle Gaze Maps

Static Change-Blindness: Discussion

Motorcycles are not invisible:Higher detection ratesSimilar detection timesSimilar gaze maps

Saliency maps do not predict gaze maps

Solving motorcycle collisions through conspicuityIs solving a problem that does not existAnd it is solving it the wrong way

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Dynamic Change-Blindness

But these images were static

What happens when people actually drive?

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Dynamic Change-Blindness

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Dynamic Change-Blindness 1

Ss Drove down a straight road

Screens flickered onceA parked vehicle was removed

Ss indicate change detection

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Dynamic Change-Blindness 1

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0

10

20

30

40

50

60

70

80

90

100

Motorcycle Car

Pe

rcen

t d

ete

ctio

nDetection Rate

t58 = 2.03p = .047

Motorcycles are detected more frequently than cars

95% Confidence Interval

Ss Drove toward intersection

Screens flickered onceA vehicle was removed on

half the trials(entering or exiting)(car or motorcycle)

Ss indicate change detection

Dynamic Change-Blindness 2

SDT: Was ist das?

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Target present Target absent

Target reported

Hit False Alarm

Target not reported

MissCorrect

Rejection

Dynamic Change-Blindness 2

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Motorcycle Car

d'

Sensitivity

0

1

2

3

4

5

6

7

8

Motorcycle Car

β

Bias

t40 = 3.48p = .001

t40 = .24p = .81

95% Confidence Interval

Dynamic Change-Blindness: Discussion

Results replicate findings from static change blindness experiments

Motorcycles are not invisible:Higher sensitivity for motorcycles than for cars

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Conclusion

Motorcycles are (very) visible.

Why?

Sensory conspicuity is not the issue.

Efforts should be directed at education

Because the problem is likely a judgement issue

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Acknowledgments

Daniel M. BernsteinFarhad D. DasturDavid J. Froc

RAsDawn-Leah McDonaldJohn Dema-alaKevin SmithCarley WoodAndrew LoweryAmaris TokJackie KingAaron Richardson

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Questions?

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Additional Slides

Braking Behaviour

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Additional Results

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0

2

4

6

8

Car Motorcycle

Me

an F

ixat

ion

Co

un

t

Fixation Count

95% Confidence Interval

Additional Results

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0

1

1

2

2

3

Car Motorcycle

Tim

e t

o F

irst

Fix

atio

n (

s)

Time to First Fixation

95% Confidence Interval

Additional Results

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0

200

400

600

800

1,000

1,200

Car MotorcycleMe

an T

ime

on

Tar

get

(ms)

Time On Target

95% Confidence Interval