Mobile Phone Use in a Driving Simulation Task: Differences in

Eye Movements

Stacy Balk, Kristin Moore,Will Spearman, & Jay Steele

The Problem

Each year there are nearly 43,000 traffic collisions (NHTSA, 2005)

Traffic crashes are responsible for 40 percent of deaths of people aged 15-20 (National Transportation Board, 2005)

Inattention is the most sighted cause for traffic crashes (NHTSA, 2000)

Background

When driving, & mental workload is increased (e.g. high traffic, visual clutter, etc.) drivers are less able to maintain high situation awareness.

A reduction in situation awareness may result in a lowered ability to optimally perform driving tasks (Gugerty 1997).

Background Cont.

In addition to normal aspects of driving, conversing on mobile phones has been shown to dramatically increase mental workload (Recarte & Nunes, 2003).

This is especially troubling due to the recent increase in the popularity of mobile phones (Incisive Interactive Marketing, 2005)

Background Cont.

85% of all mobile phone owners talk on their phones at least occasionally while driving (NHTSA, 1997)

21% of crashes or near crashes reported by respondents involved at least one driver using a mobile phone (Seo & Torabi, 2004).

Previous Work

Strayer & Johnston (2001) found participants who used a mobile phone (both hand-held and hands free) performed worse in a driving task compared with participants who passively listened to radio broadcasts or books on tape.

Thus the ‘hands’ aspect is not what degrades driving performance

Previous Work cont.

Strayer et al. found that people that talking on mobile phones in a driving task were more likely to experience ‘looked-but-failed-to-see’ errors (2003)

Crundall et al. (2004) found that people talking on mobile phones have shorter fixation durations – which may account for ‘looked-but-failed-to-see’ errors

Previous Work cont.

It has been well established that talking while driving degrades driving performance.

It is not known, however, which aspects of ‘good’ driving are affected when talking on a mobile phone while driving (Gugerty, 2004)

Purpose

Engaging in TMWD increases driving errors as well as ‘looked-but-failed-to-see’ errors, it is not known how visual search strategies are modified according to the specific driving task.

The current study sought to quantify if/how visual search patterns change while engaging in a mobile phone conversation as well as combined with potentially hazardous driving situations

Participants

16 (11 female) Clemson University undergraduate students

20/20 or corrected to 20/20 vision A valid drivers’ licenseAt least 2 years driving experience (M =

3.5 years). One person was not able to participate

due to poor tracking

Apparatus

Tobii 1750 eye tracker Sampling rate of 50 hertz 1280 x 1024 display 17 LCD screen

Design

Between subjects, 2 x 2 design. 8 people (3 male, 5 female) participated in

the mobile phone condition 8 people (2 male, x 6 female) participated

in the non-mobile phone condition. All participants viewed 12 trials with 4

vehicles and 12 trials with 7 vehicles in the driving scene.

Development of the Driving Simulator

C++, OpenGL, SDLDynamic ROI generationSynchronization of frame rate and eye

trackerMirrors

Language task

Pimsleur Japanese language learning compact disk set for beginners

3 language aspects: Listening Repeat Generate

Synced to begin and end with each driving scene

Procedure

Participants were given instructionsPractice trialsCalibrationView trials (people in the mobile phone

task ‘spoke’ simultaneously)Answered a question about what occurred

during the sceneConfidence in their response

Procedure

After the completion of the 24 trials, people responded to a questionnaire about their attitudes and thoughts about mobile phones

Results

People on the mobile phone answered fewer questions about the scene correctly F (1, 14) = 49.594, p < .001 (37% vs. 68%)

People in the non-mobile phone group were more confident in their responses F (1, 200) = 23.314, p < .001. (4.03 vs. 3.18)

Overall people answered more questions with 4 vehicles correctly than with 7 F (1, 380) = 11.861, p = .001. (60% vs. 44%)

Results

Survey Results

All participants owned a mobile phone On average, participants reported using their

mobile phone ‘sometimes – often’ while driving 4 participants reported using their phone nearly

every time they drove. All felt others’ driving performance is degraded

while TMWD However, 7 of the 16 participants felt their

driving performance was only degraded slightly or not at all

Eye Data Analysis

Removed bad dataVelocity filter to determine fixations and

durationsROI output from driving simulator

compared with fixations

Eye Data Results - Overall

Mobile Phone Fewer total valid points

Percentage of fixations of total eye points were not different

No Mobile Phone Larger number of total

fixations

The spread of the fixations were not different

Eye Data Results – ROIs over whole task

Mobile Phone Less time spent in the

ROI Duration of fixations

was less (supports looked-but-failed-to see hypothesis)

No Mobile Phone More fixations in the

ROI

Eye Data Results – ROIs during the event

Mobile Phone Less time spent in the

ROI Duration of fixations

was less (supports looked-but-failed-to see hypothesis)

No Mobile Phone More fixations in the

ROI

Discussion

Language task: Controlled speed of conversation Interest level Etc.

Low-fidelity vs. high fidelity simulatorEye-data ‘thinking’ phenomenon

Conclusions / future work

People may not be aware of decreased performance when TMWD

Repeat the expt. with a more ‘involved’ task

Examine the validity of the language task

Questions!