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					Measurement of Workload by Peripheral Arterial
                Tone (PAT)

Allon Kahana, Daniel Gopher, Arthur Grunwald, Cristina Iani
                       Peretz Lavie




               Technion – Israel Institute of Technology
                         Haifa 32000, Israel



                            Minerva presentation
  VINTHEC II
     Introduction
            PAT – Peripheral arterial tone. Development of Itamar
             and the Technion.
            The PAT measures peripheral vasoconstriction, that is
             argued to indicate sympathetic activity.
            Three different laboratory studies found the PAT to be
             sensitive for mental work load:
              Iani, C., Gopher, D., Lavie, P. (2001)
              Iani, C., Gopher, D., Grunwald, A.J. and Lavie, P. (2002)
              Yariv Y. (thesis, 2004)




                                   Minerva presentation
VINTHEC II
    The present study


            The aim of the study –
              To investigate the feasibility of using the PAT in a
               simulated natural environment
              To compare the PAT measure of work load to Heart rate
               and Pupil dilation measures.
              To check sensitivity of the PAT to long term load and
               short duration load.




                             Minerva presentation
VINTHEC II
    The present study


            Study was conducted as part of a European research
             project – VINTHEC II – Visual Interaction and
             Human Effectiveness in the Cockpit.
            The experiment took place at the NLR full scale and
             full motion flight simulator at Amsterdam




                            Minerva presentation
VINTHEC II
The present study



            Ten air crews of two pilots flew two flights each.
            All flights were conducted on a Fokker 100
             simulator that simulated a generic two engine
             medium size commercial plane.
            The cockpit is very similar to Boeing 767, 737.




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Experiment setting

      Each crew flew 2 flights
      First flight with no unusual events
      Second flight with some un expected events
            After take off – purser reports ‘sick passenger’
            Primary flight display of the pilot flying failus
            Purser reports – passenger with heart attack
            Primary flight display failure (2nd time)
            The instrument landing system fails
      Flights were as standard as possible (each event
       occurred under the same flight conditions).

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VINTHEC II
Full scale flight simulator




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             Minerva presentation
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What is the PAT?
Monitoring Peripheral Arterial Tone




                   Minerva presentation
 VINTHEC II
The PAT system




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    Data analysis

      PAT, Heart Rate and Pupil Dilation were scaled to the
       rest level or to the 30 seconds ‘pre-event’ level.
      Long term work load analysis - Rest level Vs. flight level
       of load
      Post event analysis – measures analysis during the 30
       seconds following event onset (5 sec intervals)




                         Minerva presentation
VINTHEC II
             PAT system




              Minerva presentation
VINTHEC II
                             PAT data

     Vasoconstriction amplitude




                           Minerva presentation
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    Results
 Three different analyses:
  Comparison of PAT scores, Heart rate and Pupil dilation during
   Rest and flight phases.
  Comparison of post-event PAT scores, Heart rate and Pupil
   dilation.
  Reaction differences between pilots within the air crews.




                        Minerva presentation
VINTHEC II
         Comparative work load measures during flight
                           PAT                                                     Pupil Dilation

       30                                                               10
       20                                                                8
                                                                         6
       10                                                                4
        0                                                                2
    % -10                                                             % 0
                                                                        -2
      -20
      -30
                       *                                                -4
                                                                        -6
      -40                             **                                -8
      -50                                                              -10
                Rest   Flight     Pilot     Pilot                               Rest       Flight    Pilot    Pilot
                                 flying      not                                                    flying     not
                                           flying                                                            flying



* - sig. difference Rest Vs. Flight                                                    Heart rate

** - Sig. difference Pilot Flying Vs                                      20

    Pilot Not Flying                                                      10

                                                                      %    0
                                                                                       *
                                                                          -10

                                                                          -20
                                                                                Rest       Flight    Pilot    Pilot
                                                                                                    flying     not
                                               Minerva presentation                                          flying
   VINTHEC II
         Event related (all events) PAT scores, Heart rate and Pupil diameter
                                        scores

                           PAT data                                                       Pupil diameter

         0                                                            5

        -5                                                            4
                                                                      3
   % -10                                                          %
                                                                      2
      -15
                                                                      1
      -20                                                             0
         event         5   10     15       20      25   30            event          5      10    15   20   25   30
Sig. decrease of PAT                                          Sig. Pupil dialation



                                                        Heart Rate

                                       5
                                       4
                                       3
                                   %
                                       2
                                       1
                                       0
                                       event       Minerva presentation
                                                   5   10     15   20                25      30
      VINTHEC II                Sig. increase HR
        Event related measures (Primary flight display failure)

                        PAT                                                  Pupil diameter

    0                                                      10

   -5                                                      8
                                                           6
% -10                                                 %
                                                           4
  -15
                                                           2
  -20                                                      0
    event      5   10     15        20   25   30                event        5   10   15      20   25   30



                                              Heart Rate

                               10
                                8
                                6
                              % 4
                                2
                                0
                               -2
                                event
                                         Minerva presentation
                                         5    10    15    20            25       30
  VINTHEC II
Longer event related measures (Heart attack and glide slope failure)

                      PAT data                                           Pupil diameter

       0                                                   5
                                                           4
      -5
                                                           3
 %                                                     %
     -10                                                   2
                                                           1
     -15                                                   0
       event      5   10   15        20   25   30           event   5      10    15   20   25   30



                                               Heart Rate

                                 3

                                 2
                            %
                                 1

                                 0
                                 event
                                          Minerva presentation
                                          5    10    15   20        25      30
     VINTHEC II
     Event related scores – Captain Vs. First officers

               10

                5
                                                        Captain-
                0                                       PD

                                                        First
             % -5                                       Officer-PD

                                                        Captain-
              -10                                       PAT

                                                        First
              -15                                       Officer-
                                                        PAT
              -20
                event   5   10    15    20    25   30




                            Minerva presentation
VINTHEC II
                          Event related - Time shift

                              2 sec
                      5        diff



                      0




                   % -5




                    -10

             PD
             PAT

                    -15
                      event       5       10     15     20   25   30
                                                Time




                                      Minerva presentation
VINTHEC II
 Results
  Time gaps between maximum reaction of PAT, Heart rate and Pupil diameter:
   Pupil diameter – 10 sec

   PAT – 12 sec

   Heart rate – 25 sec


                   First phase - Moving                   Production of new
                   resources to the brain                 resources

                          Pupil
                          dilation                    Increased               Increase heart
      Event                                           blood
                                                                              rate
      onset                                           pressure/flow

                              Vasoconstriction
Event

  0            5               10                15              20                 25
                    Pupil                  PAT                        Heart rate
                   dilation     Minerva presentation
                                         reaction                      reaction
 VINTHEC II
                           Conclusions I
                         Overall load of flight


     1. PAT measures are sensitive to the overall continuous load
of
         flight. Average increase of load during flight is 37%, relative
to
         rest period.

     2. There is a significant difference between PF and PNF in
     overall
        load. The pilot not flying reveals higher load levels.



                              Minerva presentation
     VINTHEC II
                      Conclusions II
             Response to specific flight events


1.There is an additional increase in load in response to event
which is
  significantly identified by the PAT measures, Pupil dilation
and decrease in heart rate.

2. The load increase for captains is much higher than for first
   officers, independent of the role that they assume in the
present
   flight (PF or PNF).


                       Minerva presentation
VINTHEC II
                    Conclusions III



1.PAT measure is a good technique to measure mental load
   •Sensitive
   •Valid
   •Non intrusive
   •Both continuous work load and discreet event related work
   load can be measured concurrently.




                      Minerva presentation
VINTHEC II

				
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