Mobile Phone Use in a Driving Simulation Task: Differences in Eye Movements

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Mobile Phone Use in a Driving Simulation Task
Differences in Eye Movements

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

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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)

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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).

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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)

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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).

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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

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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

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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)

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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

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Participants

• 16 (11 female) Clemson University undergraduate
  students
• 20/20 or corrected to 20/20 vision
• A valid drivers license
• At least 2 years driving experience (M 3.5
  years).
• One person was not able to participate due to
  poor tracking

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Apparatus

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

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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.

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Development of the Driving Simulator

• C, OpenGL, SDL
• Dynamic ROI generation
• Synchronization of frame rate and eye tracker
• Mirrors

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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

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Procedure

• Participants were given instructions
• Practice trials
• Calibration
• View trials (people in the mobile phone task
  spoke simultaneously)
• Answered a question about what occurred during
  the scene
• Confidence in their response

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Procedure

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

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Results

• People on the mobile phone answered fewer
  questions about the scene correctly F (1, 14)
  49.594, p lt .001 (37 vs. 68)
• People in the non-mobile phone group were more
  confident in their responses F (1, 200) 23.314,
  p lt .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)

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Results
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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

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Eye Data Analysis

• Removed bad data
• Velocity filter to determine fixations and
  durations
• ROI output from driving simulator compared with
  fixations

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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

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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

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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

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Discussion

• Language task
• Controlled speed of conversation
• Interest level
• Etc.
• Low-fidelity vs. high fidelity simulator
• Eye-data thinking phenomenon

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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

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Questions!