Lectures 32: Attention and Models of Information Processing

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Lectures 32 Attention and Models of Information
Processing
Readings Chapanis (Chapanis, 1996, chapter 6,
pages 206-211)
09/10/99
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Motivating Questions

• How do people process information?
• How do people figure out and attend to what is
  important?
• How can we design accordingly?

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The Human Brain
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Simplified Information Processing Model
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Operator-Machine Model
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Human Information Processing
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Human-Machine System Processing
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Definition of Attention

• a filtering process carried out by the brain.
• we "pay attention to," select out, or concentrate
  on those things we want to receive,
• we filter out the rest.

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Three Types of Attention

• Selective attention (choose what to focus on)
• Divided attention (trying to do more than one
  thing at once)
• Captured attention (designing stimuli that
  capture people's attention)

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Things we generally dont pay attention to when
writing

• the noise of the keys on the keyboard
• the sound of traffic outside
• the humming of the computer
• dirt on the computer screen
• variations of line width in the computer font
• Heartbeat, breathing, etc.

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Tasks require us to block out non-task information

• E.g., the fact that the hands feel cool, the
  neck is sore, the breathing is slow
• Work performance shouldnt suffer because of an
  itch in ones shoulder, or because one feels the
  pressure of the back of ones legs against the
  chair etc.
• If we couldn't block out non-task information,
  then it would be very hard to get work done.

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Selective Attention

• we choose which piece of information we want to
  focus on amongst all the available information.
• It is a bit like choosing a sandwich from a tray
  of sandwiches.
• Stimuli can by selected by
• moving eyes - to the item of interest
• turning heads - to the sounds we want to hear.

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"Cocktail-party Effect"

• occurs when several people are talking at the
  same time and you want to focus on, or listen to
  , one particular person.
• We do this task quite well.
• Cocktail party - noisy environment where there
  are many conversations going on at the same time.

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Selection and Attention (Norman)
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Eye Movements and Attention
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Perception-Action Cycle
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Perceptual Cycle in a Nuclear Power Plant
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Definition of Divided Attention

• Time sharing
• Happens when one operator is required to perform
  two or more different tasks simultaneously or in
  rapid alternation.
• Results in degraded performance if combined
  demands of tasks exceed the capacity of the
  individual.

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Capturing Attention

• use of alerting signals or critical information
  to shift attention from a task at hand to an
  alarm, caution and warning displays.
• E.g., the warning sound of an emergency vehicle.

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Design of Alarms I

• should be sufficiently different from other
  sources of sensory input in the environment
• immediately recognizable as alarms.
• each abnormal condition should trigger a unique
  alarm
• (ie. it should be possible to identify rapidly
  the condition to which the alarm is calling
  attention.)
• it should be easy to determine the source of the
  alarm

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Design of Alarms II

• convey information about the approximate level of
  the danger, hazard, or abnormality
• prioritize in the case of multiple simultaneous
  abnormal conditions
• Prioritize according to importance or degree of
  hazard
• signal only the most important condition(s)
• alarms for lesser problems should be suppressed.
• dont worry about a hangnail if a main artery is
  severed!

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Lessons Learned

• Attention directs mental and perceptual resources
  to task relevant information
• Different types of attention
• Different types of attentional resource
• Need to design tasks and displays to capture and
  use human attention appropriately

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Factors Affecting Operator Performance

• machine interfaces environments in which the
  operators work
• instructions provided
• quality and quantity of training
• physical and mental stress
• operator's nutritional and psychological needs

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Discussion Question

• Why can perform some things at the same time
  without apparent harm, while other combinations
  of activities seem to conflict with each other?
• look at the pattern of conflicts and synergies
• Examine underlying factors that determine
  competition between attentional resources.

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Visual vs. Auditory Channel
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The Gas-Tank Model
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Resource Model

• performance will suffer if the demands of the
  task exceed available resources.
• Imagine a gas tank full of attentional resources
• If you don't have enough gas in the tank, then
  you can't complete the task.
• where does the gas come from?
• Is there one type of gas or many?
• How is new gas obtained, or the gas tank
  refilled? Does the size of the gas tank grow or
  shrink in different conditions?
• How many different gas tanks are there?

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Multiple Attentional Resources
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Conclusions

• Attention is vital for Work
• Attention links perception and cognition
• Researchers are still studying attention
• Design for task requirements, e.g., capturing
  attention, helping the person to select the
  important information, and helping the person to
  allocate multiple attentional resources to the
  task