Download memory system

Human Computer Interaction (HCI)
Dr. Muhammad Tahir
Chapter 3
Human Memory
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Memory
 Name
the persons you met today?
 Count the number of items you last purchased from market?
 Objects are missed out
 Objects recalled in wrong order
Why?
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Memory
Why?
Its our ability to store and retrieve information !
i.e. this is the job of our memory system !
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Memory
 How
memory works?
 How we remember things?
 How we recall / retrieve information?
 What happens when we forget?
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Memory
There are three types of memory function:
Sensory memories
Short-term memory
Long-term memory
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Sensory Memory (SM)
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Sensory memory
 Buffers for the information received through senses
 Iconic memory:
 buffer for visual stimuli
 Echoic memory:
 buffer for aural stimuli
 Haptic memory:
 buffer for tactile stimuli
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Sensory memory
 Buffers for the information received through senses
 Constantly overwritten by new information
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Sensory memory
 Iconic memory
 Move finger in front of the eye
 Creates a persistent image
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Sensory memory
 Echoic memory
 Provides play-back of information
 Asking question while reading!
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Sensory memory
 Haptic memory
 Receive information through the sense of touch
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Short Term Memory (STM)
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Short-term memory (STM)
 Also known as working memory
 Scratch-pad for temporary recall of information
 To store information required for a short amount of time
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Short-term memory (STM)
 Examples:
 Multiply 35 by 6
 Read one sentence
 i.e. used to store intermediate results
 Rapid access ~ 70ms
 Rapid decay ~ 200ms
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STM Examples
 Limited capacity 7± 2 chunks
 Chunking can increase the STM capacity
212348278493202
0121 414 2626
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STM Examples
 Patterns can also increase the STM capacity
HEC ATR ANU PTH ETR EET
Difficult to remember
THE CAT RAN UP THE TREE
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STM
 Closure
 You look up a number in telephone directory
 You rehearse it before dialling
 Once dialling is complete, there is a feel of relief
 This is called closure
 Helpful in chunking of information
 Helpful in providing feedback to novice and expert users
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STM
 Free recall
 Recalling lists in any order
 Easier than recalling in order
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STM
 Primacy effect
In a list of items
 Words at the beginning of the list are generally well remembered
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STM
 Recency effect
In a list of items
 Words at the end of the list are generally well remembered
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STM
 Interference
 Primacy / Recency effect is eliminated due to interference
For example counting backwards !
 Does not affect the already stored information
o Thus there exists another type of memory
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Long Term Memory (LTM)
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Long-term memory (LTM)
 Repository for all our knowledge
 slow access ~ 1/10 second
 slow decay, if any
 huge or unlimited capacity
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Long-term memory (LTM)
 Stores information from STM through rehearsal
 episodic
– memory of events and experiences in serial form
– what you had for dinner, where you went on saturday
– reconstruction of events possible
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Long-term memory (LTM)
 Stores information from STM through rehearsal
 semantic
– structured memory of facts, concepts, skills acquired
– what different words mean, how many inches in a foot
– semantic LTM derived from episodic LTM
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Long-term memory (cont.)
 Semantic memory structure
 allows access to information
 represents relationships between bits of information
 supports inference (e.g. dog: 4 legs, hound: 4 legs)
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LTM - semantic network
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Semantic network as a model of
memory organization
Long-term memory (cont.)
 Model: semantic network
 inheritance – child nodes inherit properties of parent nodes
 relationships between bits of information
 supports inference through inheritance
 Knowledge is organized by association (e.g. cartoon dog character)
 Example: story of unfamiliar culture / recall
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LTM - semantic network
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Semantic network as a model of
memory organization
Activities of LTM
 Three main activities
 Information storage or remembering
 Forgetting
 Information retrieval
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LTM - Storage of information
 Rehearsal
 information moves from STM to LTM
 Total time hypothesis
 amount retained proportional to rehearsal time
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LTM - Storage of information
 Only repetition is not enough
 If information is not meaningful, difficult to remember
 Faith, Age, Cold, Logic, Idea, Value, Past
 Boat, Tree, Cat, Child, Plate, Mosque, Head
Which set is easy to remember?
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LTM - Forgetting
 Decay
 information is lost gradually but very slowly
 Interference
 new information replaces old
 Change of telephone numbers
 old may interfere with new
 You drive to your old house rather than the new one
 LTM forgetting is affected by emotions
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LTM - Retrieval
 Recall
 Information reproduced from memory
 Can be assisted by cues, e.g. categories, imagery (ex: lists)
 Let users categorize/visualize categories (helps in easy recall)
Child, red, plane, dog, friend, blood, cold, tree, big, angry
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LTM - Retrieval
 Recognition
 Information gives knowledge that it has been seen before
 Less complex than recall - information is cue
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Improve your memory by
1- Visualizing things
2- Creating associations between them
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Memory role in interface design
 Don’t play with user’s memory
 Enter date in the following formats:
xx/xx/xx
xx/xx/xxxx
xx/xxx/xx
?
 Give users visual and audible cues to complete their tasks
 Beep for an error message
 Copying of data (bar chart / progress bar gradually filled in)
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Memory role in interface design
 Users are not expected to remember a different sequence
of events
 Change of QWERTY keyboard to AZERTY keyboard
 Stroop Effect
Red Green Blue Black
Red Green Blue Black
Red Green Blue Black
Red Green Blue Black
Read text first and then the text colour. Try again!
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Memory role in interface design
 Stroop Effect
Red Green Blue Black
Red Green Blue Black
Red Green Blue Black
Red Green Blue Black
 Result
 Once people are learned to read, they read whatever is put in front
of them
 In case of two sources of information, people slow down
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Memory role in interface design
 Stroop Effect
Red Green Blue Black
Red Green Blue Black
Red Green Blue Black
Red Green Blue Black
 Result
 When presented with two sources of information (e.g. text and
colour), you can’t avoid reading !
 Used to check processing speed and selective attention
(concentrating on one aspect and ignoring others)
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HCI: Recommended books
1.
Human Computer Interaction by Alan Dix , Janet Finlay,
Gregory D. Abowd, Russell Beale … (main text)
2.
The essence of Human Computer Interaction by Christine
Faulkner
3.
The psychology of everyday things by Donald Norman
Additional valuable resource:
www.hcibib.org
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