IE 486 Work Analysis

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IE 486 Work Analysis Design II
Instructor Vincent Duffy, Ph.D. Associate
Professor Lecture 5 Cognition Information
Processing Tues. Jan. 30, 2007
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An overview capabilities and limitations of our
information processing related to HF Design
1. An example re limitations in cognition 2.
Information processing models 3. Object and
pattern recognition 4. Transfer to working
memory 5. Working memory 6. Long term memory 7.
Attention and mental resources 8. Conclusions
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IE 486 - Lecture 5 - QOTD

• QOTD 1 Ambiguous or unclear sensory features can
  be recognized as different objects depending on
  context. This illustrates___________.
• QOTD 2 The human sensory register can hold
  _____________. This illustrates ___________.

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1. An example re limitations in cognition

• Drive to downtown mall for holiday shopping
• Enter the malls 10 story parking structure
• Drive up spiral until you find a space near the
  elevator
• Proceed down the elevator and into the mall
• 5 hours later bring many bags of gifts for
  friends and relatives
• Return to the parking garage
• Get out on 6th floor but cant find the car!
• then wander to two other levels before finally
  locating the car.

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2. Information processing models

• Perceptual Encoding
• Central Processing
• Responding

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2. Information processing models

• Perceptual Encoding
• includes issues of chapter 4 5 on senses
• Bring knowledge to the sensory input give it
  meaning
• Central Processing
• Includes concerns about attentional resources
  and issues related to perception, memory and
  thoughts about the need for decision making
  related to chapter 6
• Responding
• The line between decision making and problem
  solving is a bit blurred
• Includes decision making chapter 7
• For additional detail see figure 6-1 p. 122

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Information processing model (p.122)
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3. Object and pattern recognition

• Feature analysis
• It is a 3 step process according to Anderson
• Break into component features
• Draw out stored patterns from long term memory
  to match the features
• Decide which stored pattern is the best match

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3. Object and pattern recognition

• Feature analysis
• It is a 3 step process according to Anderson
• Break into component features
• Draw out stored patterns from long term memory
  to match the features
• Decide which stored pattern is the best match
• Eg. If we see the word the enough times,
• we begin to process it automatically as a global
  shape
• rather than analyze the individual features
  (parts of letters and individual letters).

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3. Object and pattern recognition

• Top-down and bottom-up processing
• Ambiguous sensory features can be recognized as
  different objects depending on context.
• Illustrates the benefits of redundancy in
  presenting information.
• We may not need to know all of the letters of the
  word to recognize it.

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3. Object and pattern recognition

• QOTD 1 Top-down and bottom-up processing
• Ambiguous sensory features can be recognized as
  different objects depending on context.
• Illustrates the benefits of redundancy in
  presenting information.
• We may not need to know all of the letters of the
  word to recognize it.
• I cxn rxplxce xvexy txirx lextex of x sextexce
  xitx an x, anx yox stxll xan xanxge xo rxad xt
  ix wixh sxme xifxicxltx.

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3. Object and pattern recognition

• Top-down and bottom-up processing
• Ambiguous sensory features can be recognized as
  different objects depending on context.
• Illustrates the benefits of redundancy in
  presenting information.
• We may not need to know all of the letters of the
  word to recognize it.
• I cxn rxplxce xvexy txirx lextex of x sextexce
  xitx an x, anx yox stxll xan xanxge xo rxad xt
  ix wixh sxme xifxicxltx.
• Typically we think of object recognition as
  bottom up (eg. See the round object - ball).
• Yet context may tell us if it is a basketball or
  beach ball.

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3. Object and pattern recognition

• When stimulus is high quality, bottom up
  processing will be most influential.
• As quality of the signal/stimulus is degraded,
• increases in context and redundancy will be
  necessary
• to enable more top-down processing and high level
  of recognition.

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3. Object and pattern recognition

• When stimulus is high quality, bottom up
  processing will be most influential.
• As quality of the signal/stimulus is degraded,
• increases in context and redundancy will be
  necessary
• to enable more top-down processing and high level
  of recognition.
• Implications
• Designers should not do usability testing for
  icons in a lab
• without considering surrounding environment
  and/or task context.

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4. Transfer to working memory

• The human sensory register can hold
• visual information for about 1 second
• auditory information for about 3-5 seconds
• QOTD 2 Consider what does this illustrate?

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4. Transfer to working memory

• Limitations in information processing
• Only a limited amount of information can be
  brought from sensory to working memory
• Typically overlooked in system design

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4. Transfer to working memory

• Limitations in information processing
• Only a limited amount of information can be
  brought from sensory to working memory
• Typically overlooked in system design
• Working memory is limited in two ways
• Capacity and time
• Working memory is limited in
• how much information can be kept active
• how long it can be kept active

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5. Working memory

• A railroad switchman forgot he moved a train to
  an active track.
• The ensuing crash killed over 200 people
• Working memory holds two different types of
  information
• Verbal and spatial

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5. Working memory

• A railroad switchman forgot he moved a train to
  an active track.
• The ensuing crash killed over 200 people
• Working memory holds two different types of
  information
• Verbal and spatial
• Working memory is the temporary holding of
  information that is active
• Long term memory is considered the reactivation
  of information

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5. Working memory

• Working memory must be able to accommodate the
  demands and support active problem-solving
• Recall consideration given to capacity and time
  limitations
• Capacity
• 7 /- 2 chunks
• Physical and cognitive properties that bind items
  together
• Eg. 8 4 7 9 has 4 chunks
• 28 36 45 89 also has 4 chunks

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5. Working memory

• Working memory must be able to accommodate the
  demands and support active problem-solving
• Recall consideration given to capacity and time
  limitations
• Capacity
• 7 /- 2 chunks
• Physical and cognitive properties that bind items
  together
• Eg. 8 4 7 9 has 4 chunks
• 28 36 45 89 also has 4 chunks
• Chunking reduces the number of items in working
  memory and makes use of meaningful associations.
• Also, material can be more easily rehearsed.

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5. Working memory

• Some rules of thumb for design
• Minimize working memory load
• Give visual redundancy when possible
• Exploit chunking
• Note letters may be better than numbers
• Eg. 1-800-663-5900 has 8 chunks while 1-800 GET
  HELP has 3.

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5. Working memory

• Some rules of thumb for design
• Minimize working memory load
• Give visual redundancy when possible
• Exploit chunking
• Note letters may be better than numbers
• Eg. 1-800-663-5900 has 8 chunks while 1-800 GET
  HELP has 3.
• Keep numbers separate from letters
• Eg. License plates 458 GST is preferred.
• Instead of 4G58ST

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6. Long term memory

• Semantic memory
• General knowledge
• Event memory specific events- past and future
• Episodic memory past event
• Eg. An accident at work
• Prospective memory future
• Eg. Remember to do something

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6. Long term memory

• Design implications
• The user is unlikely to develop the same level of
  detail (recall) in the use of a product compared
  to the designer

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6. Long term memory

• Design implications
• The user is unlikely to develop the same level of
  detail (recall) in the use of a product compared
  to the designer
• Therefore, when possible, it is a good idea to
• Encourage frequent use of information
• Take advantage of frequency and recency
• then over time, the task may become more
  automatic
• Standardize and use memory aids
• Eg. Give list of instructions for sending fax
• Carefully design information to be remembered
• Make it meaningful and avoid the use of technical
  jargon when possible

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7. Attention and mental resources

• If we devote cognitive resources to one activity,
  others are likely to suffer
• Eg. Study of the use of cell phones and driving
  suggests that accidents are 5x more likely
• The rate is roughly equivalent to driving drunk
• Consider multiple resources
• Eg. One can not read a book and watch tv at the
  same time.
• However, one can listen to the spoken version of
  the book while watching tv.
• Visual and auditory processing requires separate
  resources.

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8. Conclusions

• Some general design implications
• Consider issues related to
• Divided attention,
• controlled vs. automatic processing
• multiple resources