Measuring Cognitive Distraction in the Vehicle

Joel CooperPrecision Driving Research

David StrayerUniversity of Utah

Trends and usage

Evaluated 403 vehicle models from top 14 manufacturers•98.3% offered Bluetooth pairing•89.8% screen in center stack•50.4% offered smartphone application integration.•94.3% offered a USB port

Available functions•Make Calls•Send and received text messages•Send and receive emails•Update social media•Control radio, climate, gps, etc.

The Driver Distraction Triad

Eyes off the Road

Manual:

Visual: Cognitive:High

Low

Moderate

Hands off the Wheel

Mind off the Drive

Trends and Questions• The Apps are coming…• Hands and eyes free is increasingly seen as the solution to

visual distraction

Generally speaking, the same task will be less dangerous if it can be achieved via an auditory / vocal interactions rather than visual / manual interactions. However…

Potential risk is momentary demand and exposure

Q: Are the potential risks of some auditory/vocal tasks greater than others?

Overview of AAA Project

• Most comprehensive study undertaken on mental workload

• Systematic analysis, 3 studies, 150 participants, 8 conditions

• Analysis of different sources of distraction• Driving simulator • Instrumented vehicle

• Develop taxonomy of cognitive mental workload• Category 1 – Workload associated with Baseline Driving • Category 5 – Workload associated with Highly Demanding

Secondary task

Sources of Cognitive Distraction

• Baseline Driving• Listen to Radio• Audio Book• Passenger Conversation

• Hands-free cell conversation• Hands-held cell conversation• Speech-to-Text task• Mental Math (OSPAN)

Evaluation Platforms

Measures

• Primary• Secondary

• Physiological• Subjective

Developing a Metric of CognitiveWorkload

• Problem: Measuring cognitive workload is notoriously difficult

• Objective: Develop robust instrument of cognitive distraction• Older technologies (e.g., radio, cell phone, etc.)• Newer technologies (e.g., speech-based in-vehicle

communication)

• Standardized rating system• Similar to other rating systems (e.g., Richter, Saffir-Simpson, etc.)

where higher ratings are indicative of greater cognitive distraction

Video of Instrumented Vehicle

Brake Reaction Time

Scanning for Hazards at Intersections

NASA TLX – Mental Workload

Cognitive Workload Scale

What does this mean in terms of risk?

• Mental Workload Distraction

• Mental Workload Risk

Increases in mental workload led to:•Reduced visual scanning for hazards•Reduced brake response time•Reduced attentional capacity (as measured by the p300 ERP)

What does this mean in terms of risk?From other research

•Inattentional blindness•Impaired judgment and decision making•General reduction in visual scanning•Reduced frequency of lane changes•Reduced stopping at intersections

However…

•Reduced fatigue•Reduced boredom•Improved lane maintenance•Increased visual attention toward forward roadway

Summary of Results

• Category 1: Baseline, Radio, Book• Category 2: Conversations (HH, HF,

Passenger)• Category 3: Text to Speech• Category 5: Mental Math

Summary and Results

• Proceed with caution!• Text-to-Speech systems may be more

mentally demanding than conversations.

Low frequency/ high risk potentially equal to high frequency/ low risk

Future Directions

• How does the quality of speech affect workload?

• How do errors in understanding affect workload?

• How does an actual system, such as Siri, fit on the scale?

• Are structured interactions more/less demanding than unstructured interctions?

Thank You!