Human Memory

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Human Memory

• Input Stimuli

Attention
Rehearsal
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Taxonomy of Forgetting

• Decay - loss over time
• Displacement - loss by exceeding capacity
• Interference - loss by confusion of similar things

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Summary of Sensory Memories

• Function buffers data from environment
• Capacity large
• Duration very short
• Forgetting decay

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Experiment

• Remember as many letters as you can

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P K S J H L Y M O
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B I G O L D M A N
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Working Memory (or STM)

• Short term information store
• Used to support information processing
• Thinking
• Problem solving
• People have some control over STM
• Rehearsal
• WM decays pretty rapidly
• A few seconds or minutes
• WM has a limited capacity - displacement
• The magic number 7 plus or minus two.

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Summary of Working Memory

• Function support problem solving, thinking
• Capacity very small - 7 plus or minus 2
• The bottleneck in memory
• Duration short
• Forgetting displacement and decay

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Pay Attention .

• 3153122367

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What is the number?
315 312 2367

• Information can be grouped into chunked so that
  we can increase our short-term memory to 7 /- 2
  chunks

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Another Example

• HEC ATR ANU PTH ETR EET

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What is the String?

• THE CAT RAN UP THE TREE
• HEC ATR ANU PTH ETR EET
• Patterns and meanings helps to increase capacity
  of short-term memory.

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Now, Whats the number again?
3153122367

• Would you promise me that you would remember this
  number next class?
• If it counts for 50 of the grade, could you do
  that?

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Chunking Defined

• Recoding small bits of information into a larger
  meaningful unit
• Why?
• Easier to keep in working memory!
• Avoids WM overload - chunk takes up only one
  place in WM

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Long-Term Memory (LTM)

• Long-term memory stores everything that we know
  -- facts, experience, knowledge, procedural rules
  of behavior, language
• LTM has huge capacity
• LTM has a relatively slow access compared to
  short-term memory
• Forgetting also occurs slowly

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Writing to Memory

• Writing to permanent memory is SLOW
• lets see if we can demonstrate this
• Get paper, get pencil
• Get ready
• try to remember the words I will say
• when I say write, write them all down in any
  order you choose

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Recognition List

• Dog
• Pencil
• Cheese
• Picture
• Tack
• Tree
• Sock
• Horse
• Cup
• Room

• Shoe
• Paper
• Clock
• Olive
• Book
• Flower
• Bicycle
• House
• Stove
• Pipe

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Contents of LTM

• Episodic
• Semantic

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Retrieval is an Active Process

• Episodic contents are autobiographical
• Memory is a reconstruction process
• what were you doing on Monday in the third week
  of September in 1996?
• In the house you lived in two houses ago, how
  many windows were there?

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Long-term Memory

• Semantic contents and associations - have to do
  with concepts and relationships

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Aids to Retrieval from LTM

• Recognition is easier than recall
• Interfaces should give cues so that the user can
  retrieve via recognition
• Menu items (words)
• Icons (images)

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Summary of LTM

• Function long-term storage
• Capacity very large
• Duration long
• Forgetting decay and interference
• LTM is not a videotape
• It is reconstructive

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Stage Theory
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Stage Theory

• Working memory is small
• Temporary storage implies decay and displacement
• Maintenance rehearsal
• Rote repetition
• Not enough to learn information well
• Answer to problem is organization

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Elaboration

• Relate new material to other material already
  learned
• Recodes information
• Attach meaning (make a story)
• e.g., sentences
• Visual imagery
• Organize (chunking)
• Link to existing knowledge, categories

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Memory - Why is it Relevant?

• Working memory
• 7 plus or minus 2 dont overload users
  WM
• LTM
• Provide cues for retrieval by recognition, not
  recall
• Names, icons, etc. should be meaningful, but what
  does meaningful mean?
• what makes sense to you may be nonsense to me
• meaningful is based on experience
• we have our own individual experiences

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Recognition over Recall

• Recall
• Info reproduced from memory
• Recognition
• Presentation of info provides knowledge that info
  has been seen before
• Easier because of cues to retrieval

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Facilitating Retrieval Cues

• Any stimulus that improves retrieval
• Example giving hints
• Software examples icons, labels, menu names,
  etc.
• Anything related to
• Item or situation where it was learned
• Can facilitate memory in any system
• What are we taking advantage of?
• Recognition over recall!

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Focusing attention at the interface

• Structuring information
• Spatial and temporal cues
• Color
• Alerting techniques
• Flashing and reverse video and auditory warnings

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Summary and implications

• Memory
• Three types sensory, WM, LTM
• Use cues in WM to get to LTM
• Interference can make LTM hard to access
• Cues can make it easier to access LTM

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Learning

• People are always learning.
• People use prior learning to support new leaning.
• People often learn by doing
• But learning style varies
• Users dont read manuals but work by copying and
  asking

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Learning difficulties

• Learning is difficult
• Learners lack basic knowledge
• Learners have trouble following directions
• Interface features may not be obvious
• Help facilities do not always help

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Design implications

• Design interfaces that encourage exploration
• Design interfaces that constrain and guide users
  to select appropriate actions
• Dynamically link representations and abstractions
  that need to be learned

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Problem Solving

• People like to solve problems
• People dont like unsolvable problems.
• Process of finding solution to unfamiliar task
  using knowledge.
• Operates within human information processing
  system (e.g., STM limits, etc.)
• analogical mapping
• Chunking
• Conceptual rather than superficial grouping of
  problems
• Think of different types of problem solving based
  on level of experience or skill

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Reading

• Several stages
• Visual pattern perceived
• Decoded using internal representation of language
• Interpreted using knowledge of syntax, semantics,
  pragmatics
• Perception occurs during latter.
• Word shape is important to recognition.
• Negative contrast improves reading from computer
  screen.

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Individual Differences

• Long term sex, physical and intellectual
  abilities
• Short term effect of stress or fatigue
• Changing through time age
• Ask yourself Will my design decision exclude a
  section of the user population?

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