CP684

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CP684

• Human Factors in Information Systems
• Week 3 - Memory...

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Memory operation

• Three main processes associated with the
  operation of memory
• Storage or Remembering
• Forgetting
• Retrieval

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• Storage or Remembering requires repeated exposure
  or rehearsal.
• Meaningful information is easier to remember.
• A list of words representing concepts is more
  difficult to remember than a set of words
  representing objects.
• Example

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Remember...

• Try to remember as many words as you can from the
  following list
• softly, smoothly, rapidly, hot, squirmy,
  indifferent, unuseable

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• How many did you manage?
• Now do the same with the following
• arm, scissors, printer, paintbrush, folder,
  pencil, alignment

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• How many could you recall?

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• keyboard commands require the commands to be
  remembered
• selecting commands from a screen require the
  commands to be recognized
• long commands using a large number of parameters
  are hard learn

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Forgetting

• Decay and Interference
• Decay Information decays more rapidly at first
  then decay slows down
• Interference New information causes loss of old
  information (aka recency effect)
• sometimes resistance to new material does the
  opposite!
• Office2000 is a good example

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Recency effect

• Last items presented are more easily
  remembered than earlier items.
• a task intervening between presentation and
  recall eliminates recency effect
• Example Office 2000 (again!) menu bars

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Retrieval

• Recall and Recognition
• Recall - Information is reproduced from memory
• Categorisation/structuring of information assists
  recall chunking
• Recognition - awareness that is viewed/acted on
  has been experienced previously.

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Memory/expectation?

• expectations of colours
• red - stop, danger, hot (but also speed)
• blue - cold
• green - go (but also calm, slow)

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Processing

• Anything that is seen by our eyes has to be
  processed
• processing difficulties depend on complexity of
  the visual scene and on our previous memory of
  that scene

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Visuals

• Images that we already are familiar with are
  simply matched to images stored in our memory
• takes little time and minimal effort
• example familiar icons such as diskette/save
  scissors/cut printer/printouts
• Grab a pen and paper

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Your turn...

• Write down what you just saw!

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Your turn again...

• Write down what you saw.

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Visual Processing

• You have learned/memorised modern English script
• Old English characters are unfamiliar - slow
  recognition if any at all!
• Modern English script simply needs to be mapped
  to a similar character in our memory -
  understanding is speedy!

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Seeing

• Hello?!

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What information do you memorise?

• Location of object(s)
• Shape of object(s)
• Relationship of object(s) to other object(s) on
  screen
• Pictures of icons
• Colors

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Processing of scenes

• visual understanding of a scene and the time it
  takes to learn the scene depends on the number of
  unique elements that we must identify in that
  scene
• If we have already learned the scene, we record
  it as one element
• Words are recorded as a single element.

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Type and legibility

• reading is done primarily by recognising the
  overall shape of words
• not by parsing
• all uppercase text
• is harder to read than lowercase
• has no distinctive features to catch eye

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Type and legibility

• Words do not make much sense if only the bottom
  half is visible

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Better?

• Legibility is linked to the top of words

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Complex scenes

• Examples of complex scenes related to Web pages
• much also relevant to GUI design

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Visual scanning stages
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Complex Scene
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Another example
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Design considerations

• Balance
• Equal weight of screen elements
• Left to right, top to bottom
• Consistency
• Create standard and consistent spacing on
  horizontal and vertical alignment points
• Predictability
• Put things in predictable locations on the screen

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MS-Word
Paintshop Pro
Netscape Navigator
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Last but not least...

• Like a good painting, guide the eye through the
  task in an obvious way
• Eye attractions are
• bright elements over less bright
• Isolated elements over grouped
• graphics before text
• colour before monochrome
• saturated as opposed to less saturated colors
• dark areas before light
• big as opposed to small elements
• unusual shapes over usual ones

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Design Implications

• Human processing capacity is very small
• Constant danger of overload
• Inexperienced users
• willing to be led slowly by the computer
• Experienced users
• wish to take the initiative and operate the
  system rapidly
• Good design depends primarily on a solid
  understanding of human behaviour!

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THE END