CIS465: Adv. Info. Sys. Memory Systems

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CIS465 Adv. Info. Sys.Memory Systems

• Min Song
• Information Systems Dept.

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The Human Information Processing System

• To support human systems, need to know something
  about its basic characteristics
• memory
• performance characteristics
• behavior of input and output channels
• internal architecture

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The Human Information Processing System

• As with computer, one basic activity is info
  processing.
• HC Interface is for exchanging information
• So, focus on user as info processing system, and
  study how the user handles info input and output.

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Basic Information Processing Units
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Human Constraints and Task Accomplishment

• Limited available resources.
• High use, reduced processing
• Resource-limited Tasks
• Data-limited Tasks

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Reduce Memory Load

• Reduce demands on user's short-term memory
• Establish meaningful defaults
• Define intuitive short-cuts
• Visual layout of user interface should be based
  on a familiar real world metaphor
• Disclose information in a progressive fashion

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Competition for Critical Resources

• Multiple tasks interfere and compete with each
  other.
• Two basic tasks in any form of user interaction
• Functional user works with the content of the
  problem at hand (e.g., laying out a financial
  plan on a spreadsheet)
• Operational user works with the tools provided
  to do the task (e.g., moving the cursor around
  the spreadsheet or invoking spreadsheet commands).

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Competition for Critical Resources

• Functional and operational aspects compete for
  same scarce resources.
• Skill in task performance can free up cognitive
  resources
• overlearning, chunking

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Basic Processes of Human and Computer Systems

• Computers work in cycles
• read input data, convert to internal form
  (read-scan phase)
• interpret the data (think phase),
• provide an output response to the input (response
  phase).
• Humans process data in a similar cycle
• read and/or scan the input data presented to them
  (read-scan)
• interpret this data by thinking about it (think
  phase)
• prepare appropriate response by sending signals
  to the motor system (e.g., speech) (response).

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Basic Processes of Human and Computer Systems

• Three basic human systems handle input and output
  for the cycle
• 1. the perceptual system (read-scan)
• 2. the cognitive system (think)
• 3. the motor system (respond)

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The Perceptual System

• The basic perceptual systems are
• auditory
• visual
• touch
• Each has a buffer, preprocessing and connection
  to cognitive system

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The Cognitive System

• holds new information short term memory (STM)
  aka WM
• tries to match it to elements in long term memory
  (LTM)
• If the information is completely new,
• relatively few matches are found
• user has to rehearse info in STM to keep it from
  decaying
• might store it in LTM

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The Cognitive System

• Example of rehearsal remembering a phone number

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Short Term Memory

• small capacity, fast read/write speeds, highly
  volatile
• Tasks which can cause forgetting in STM include
  those with
• distractions (e.g., multiple attention grabbing
  items happening at the same time).
• low discrimination between presented information
• large number of unique (unrelated) items

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Long Term Memory

• unlimited capacity, slow read/write speeds (about
  5 seconds per item stored), fairly stable
• forgettinglosing links, not nodes
• recall tends to be more general than specific
• declarative facts
• procedural rules, how to do things

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The Motor System

• comprised of many different muscle systems
• controlled primarily by the visual system
• Motor movements viewed by the visual system,
  which sends its information on to the cognitive
  system, which then makes minor adjustments in the
  motor movements. These are sent as commands to
  the muscles to adjust the movement.

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