ATTENTION!!!

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ATTENTION!!!
ATTENTION RESOURCES
From page 147 of Wickens et al.
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ATTENTION!!!

• A "flexible, sharable, processing resource of
  limited availability".
• Our ability to attend to several things at once
  (time-sharing) depends on
• Controlled vs automatic processing
• Skill
• Which resource(s) required
• Attention tasks can be divided into 4
  categories ...

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1. Selective Attention

• "requires the monitoring of several channels
  (sources) of information to perform a single
  task.
• Example scanning cockpit instruments
• Limitations
• As the number of channels of information
  increases, performance declines (even when the
  overall signal rate is the same).
• Can select inappropriate aspect(s) of the
  environment to process.
• "Cognitive tunnel vision" in complex environments
  with many displays, especially under stress.
  (Example 1972 Eastern Airlines crash in the
  Everglades).
• Errors associated with Selective Attention are
  generally the result of an intentional, but
  unwise choice.

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Selective Attention

• Design Guidelines
• Place frequently sampled displays together.
• Place sequentially sampled displays together.
• Use external aids/reminders to help people
  remember when the display was last sampled.

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2. Focused Attention

• Requires attending to one source of information
  at the exclusion of all others
• Examples
• Trying to study while someone else is talking on
  the phone
• Trying to enter numerical data into Excel while
  others are discussing basketball scores and
  stats.
• Limitations
• Impossible to ignore a visual stimulus within 1
  degree of visual angle of the visual information
  you are interested in.
• Auditory stimuli sufficiently loud with respect
  to the signal you are interested in, and/or
  similar to it, can interfere with the signal.
• Errors associated with focused attention are
  generally unintentional, driven by the
  environment.

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Focused Attention

• Design Guidelines Parallel vs serial processing
• Parallel processing is helpful when
• two tightly coupled tasks are performed
  simultaneously
• e.g., control roll and pitch of aircraft
• two or more information sources imply common
  action (redundancy gain)
• Parallel processing is harmful when
• similar aspects of different stimuli must be
  processed (resource competition)
• e.g., listen to air traffic control and input
  waypoints into the onboard computer
• two or more stimuli imply different actions
• e.g., a batter distracted by a moth

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3. Sustained Attention

• "the ability of observers to maintain attention
  and remain alert over prolonged periods of time."
• Example Security guard watching monitor for
  intruders.
• Limitations
• Vigilance decrement - a decline in the speed and
  accuracy of signal detection with time on the
  task (found more in the laboratory than in real
  world tasks).

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Sustained Attention

• Design Guidelines
• Appropriate work-rest schedules and task
  variation.
• Increase the conspicuity of the signal.
• Reduce uncertainty as to when and where.
• Training.

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4. Divided Attention

• "two or more separate tasks must be performed at
  the same time, and attention must be paid to
  both.
• Example Driving and talking to a passenger.
• Limitations
• Time-sharing ...

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The Resource Metaphor of Attention

• Time-sharing (or doing two tasks simultaneously)
  is difficult because we have limited attention
  resources.
• The Performance-Resource Function (PRF)

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The Performance Operating Characteristic (POC)
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Limitations of the "single-resource" theory of
attention

• Difficulty insensitivity
• In some experiments it has been shown that making
  one time-shared task more difficult has no effect
  on the performance of the other.
• Perfect time-sharing
• Structural alteration effects
• In some experiments it has been shown that
  altering the structure (but NOT the difficulty)
  of one task affects performance on the other.
• Example Manual vs vocal responses to a tone
  discrimination task while tracking.

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Multiple-Resource Theory

• Instead of one "pool" of resources, there are
  several different capacities of resources
• Codes spatial or verbal
• Modalities visual or auditory
• Stages of processing early (encoding/central
  processing) or late (responding)
• The more resources are shared, the more tasks
  will interfere.

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Multiple-Resource Theory

• To the extent that tasks demand separate rather
  than common resources
• Time-sharing will be more efficient
• Difficulty insensitivity will be observed
• The POC will be more "boxy"

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Limitation of Multiple Resource Theory

• The three proposed dimensions (stages, codes,
  modalities) do not account for all experimental
  findings. For example
• Tasks with different rhythmic requirements are
  hard to time-share.
• Control dynamics affect the efficiency of
  time-sharing a manual tracking task with another
  task.

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Implications Design Recommendations

• Since spatial and verbal codes draw upon separate
  resources, time-sharing manual and verbal
  responses is highly efficient (assuming that the
  manual response is spatial in nature and that the
  vocal response is verbal). Example
• pilots fly the airplane (spatial, manual task)
  and simultaneously talk to air traffic control
  (verbal, vocal task).
• This example also demonstrates different
  modalities (visual and auditory) which also draw
  from separate resources
• therefore
• Design systems to support a mix of manual and
  vocal responses for time-shared tasks.

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Multiple Resource Theory

• The effect of training
• Training can make tasks data limited rather than
  resource limited
• Data limited tasks can coexist more easily than
  resource-limited
• Reasoning behind part-task training paradigms
• People can also be trained to timeshare tasks
  more efficiently
• Rapid switching between tasks
• True multi-tasking