An Empirical Investigation into
                    Dual Task Trade-offs while
                       Driving and Dialing
...
acknowledgments




           •     Dan Markley and Mark Zuber
                -    hacking the TORCS software and hardwa...
the problem of doing more than one
        thing at once

           •     people frequently use a mobile device while
   ...
the problem of doing more than one
        thing at once

           •     making use illegal does not work
              ...
approaches

           •     design heuristics
                -    Green’s 15-second rule: IF a task can be completed in ...
why interleave tasks?



           •     psychological constraints limit task parallelism
                -    To drive w...
how might limited resources be divided
        between two or more continuous tasks?

           •     simple model
      ...
explore permutations ...


                Task A
              Switch Cost
                Task B
                       ...
speed/accuracy trade-off
        (Brumby et al., 2007, CHI)
                                                            st...
the question at hand ...


          •     previous studies have focused exclusively on
                demonstrating dele...
experiment: main points


        •     8 participants

        •     dialing task on a clam-shell phone
             -   ...
experiment: main points


           •     driving speed manipulated:                   fast vs. slow


           •     t...
results: dial time



                                                            •   single-task dial time is
           ...
results: lateral
                                                                 deviation




    •    single-task later...
task objective affects strategy
        more likely to switch between chunks than within chunks (xxx-xxx-xxxx)




Duncan ...
summary of findings

           •     people can adjust their multitasking strategy
                 dependent on task obje...
implications


           •     total time distracted is less important than
                 extent to which driver makes...
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An Empirical Investigation into Dual Task Trade-offs while Driving and Dialing

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Describes an experiment investigating strategic variability in cell-phone dialing while driving. Results suggest that designing devices to facilitate bursts of interaction might help alleviate egregious effects of use while driving.

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An Empirical Investigation into Dual Task Trade-offs while Driving and Dialing

  1. 1. An Empirical Investigation into Dual Task Trade-offs while Driving and Dialing Duncan Brumby University College London Dario Salvucci Drexel University Andrew Howes University of Manchester Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  2. 2. acknowledgments • Dan Markley and Mark Zuber - hacking the TORCS software and hardware integration • funding: National Science Foundation (NSF) Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  3. 3. the problem of doing more than one thing at once • people frequently use a mobile device while doing something else ... - we listen to our iPod while walking through the city - we use a cell phone while we are driving a car • there is clearly a problem with doing this ... - “iPod oblivion” lead New York to contemplate banning iPod use on city streets (toptechnews.com, Feb. 2007) - driver distraction is a major contributing cause of traffic accidents Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  4. 4. the problem of doing more than one thing at once • making use illegal does not work - many countries have banned the use of handheld devices while driving ... but people continue to use their phones - in the UK 90% compliance with the introduction of ban in 2003 has since slipped to 75% compliance -- some 10 million drivers (“careless talk”, news.bbc.co.uk, 2007) • can we better design mobile devices for use in dynamic multitasking environments? Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  5. 5. approaches • design heuristics - Green’s 15-second rule: IF a task can be completed in less than 15-seconds, THEN it is safe for a driver to engage in that task • empirical data - people tend to dial in bursts of three or four digits at a time before returning attention to primary driving task • cognitive modeling - used to better understand how people multitask Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  6. 6. why interleave tasks? • psychological constraints limit task parallelism - To drive we have to look at the road - ... to write a SMS text message we have to look at the phone, - ... but the eyes have a limited field of effective view, - ... and this will lead to strategic choice. Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  7. 7. how might limited resources be divided between two or more continuous tasks? • simple model - at any given time task A or task B can be “active” - model the information flow between tasks - assume that switching between tasks carries a time cost (Allport, Styles, & Hsieh, 1994, Attention & Performance XV) Task A Switch Cost Task B Time (s) Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  8. 8. explore permutations ... Task A Switch Cost Task B Time (s) Task A Switch Cost Task B Time (s) as an upper bound there are some 28 = 256 possible ways to enter 9 key-presses while driving. Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  9. 9. speed/accuracy trade-off (Brumby et al., 2007, CHI) strategy space shows average performance for each of some 263,000 modeled strategies KEY: FA = Fastest C1F = fastest 3-4 chunking C2F = fastest 3-2-2 chunking C1S = safest 3-4 chunking C2S = safest 3-2-2 chunking SF = safest Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  10. 10. the question at hand ... • previous studies have focused exclusively on demonstrating deleterious effects of distraction • no attempt to understand possible strategic variability in behavior • we designed an experiment to investigate dual-task trade-offs • question: does task objective affect behavior? Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  11. 11. experiment: main points • 8 participants • dialing task on a clam-shell phone - repeatedly enter same 10-digit number: highly practiced - encouraged to dial as quickly as possible -- feedback given - errors had to be corrected; built-in speed/accuracy trade-off • driving task in a simulator - drive as close to the lane center as possible -- feedback given - control steering only; no acceleration or brake Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  12. 12. experiment: main points • driving speed manipulated: fast vs. slow • task objective manipulated: dialing vs. driving - participants instructed to focus on dialing as quickly as possible or on steering as safely as possible (within-subjects design, counter- balanced) - feedback given only on focus variable at end of trial • question: how does task objective affect dial- time and lateral deviation? Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  13. 13. results: dial time • single-task dial time is equivalent to dual-task dial time in the focus-on- dialing condition. • but dial time is greater when focusing on steering in dual-task conditions. Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  14. 14. results: lateral deviation • single-task lateral deviation is equivalent to dual-task lateral deviation in the focus-on-steering condition • at faster driving speeds, lateral deviation is greater when focusing on dialing in dual-task conditions. Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  15. 15. task objective affects strategy more likely to switch between chunks than within chunks (xxx-xxx-xxxx) Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  16. 16. summary of findings • people can adjust their multitasking strategy dependent on task objectives • strategy choice has consequences for performance: cannot both dial quickly and drive safely • safer to take the time to make frequent glances back to the road, even when the secondary task takes only 5 seconds Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com
  17. 17. implications • total time distracted is less important than extent to which driver makes frequent glances back to the road ... • therefore, design mobile devices to facilitate short bursts of interaction • more generally: people will use mobile devices while engaging in other important tasks, design ought to support multitasking Duncan Brumby, UCL Interaction Centre | DBrumby@gmail.com

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