Human – computer interaction Chaptter 2 – The memory
Interaction homme-ordinateur
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Memory types 1)
Immediate (sensory) memory :iconic, echoic, haptic
2)
Short term memory
3)
Long term memory
Stimuli received through the senses (vision, audition, haptiques)
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2
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Sensory memory 1)
Lasts between 0,5s et 2s
2)
Experiences proving its existence : a)
Move a finger in front of one eye : the finger is seen in several olaces at the same time
b)
Moving sparkles leave a persistent image
c)
Identifying the place where a souns is emitted needs that both ears receive the information, but the sound reaches one year first and neds time to reach the second one. A buffer memory is needed for the brain to get both sensations
Information in the sensory memory is transferred to the short term memory through a selection process which allows us to focus on one subject at a time. This can be a voluntary act (conversation test in a group) or an imposed one (like a unexpected sudden wound). What happens to the unselected informations ? Interaction homme-ordinateur
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Short term memory 1)
It is the « working » memory. It contains all information we use to act currently.
Information lasts for seconds Access time is les than 0.1 seconds 2)
Memory capacity of an average person is limited to 7 to 9 items but we operate
generally with 3 to 7 items at a time. These figures depend on the person, the item and the memorizing context (for instance the exposition time). Short term memory properties are crucial for the corrrect interpretation of reading, recognizing complex orders and executing complex tasks. If the number of items we have to work with is to big, we always find a way to group them in a way that helps us to memorize them. Experience : -
write down as many figures as you can out of this sequence
-
text analysis
-
telephone numbers
-
a computer command line with arguments paramètres
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Long term memory (1) This memeory stores factual information, procedural rules, experiental knowledge... There are 2 types of long term stored information : ➔ Declarative : can be expressed in words Episodic Semantic ➔ Procedural : corresponds to information that we use to execute some learned actions : cycling, swimming, mounting stairs, dress ourselves
Capacity : huge if not unlimited (debate) Access time longer than working memory, but less than 1 second Persistence : hours, days, month, years - if not for ever (debate). Information is moved from short term memory to the long term memory through a repetition process but not only : think about the long term effect of a psychological or physiological shock ! Interaction homme-ordinateur
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Long term memory (2)
Representing stored information ● Semantic models ● Procedural models ● Frame models
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The semantic model The semantic model is a graph in which the vertices (or nodes) reprsent concepts and oriented edges represent relations and dependencies between concepts. The graphs help us represent our knowledge about a subject or a domain Example (simplified) : I/O has
memory
CPU has
Electronic dvc.. Is a Is a
has
Chaine Hifi.
computer Processes
Is a
Is a
µ-computer Is a
desktop
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Needs electric power
Grd. syst. Is a portable
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Procedural model
The procedural model is used to represent the way we store our knowledge about situations in which we have to decide about doing something. It describes the way we bust behave in such situations through the use of IF/THEN like production rules Example : IF the dog limps THEN you must look at it's uprised paw
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The frame model Is used to repesent the way we store complex objects and/od events, normally described by several components and events. They are used as complementary to semantic and procedural models, to structure and hierarchically organize our knowledge The frame model is build using frames to fill with fixed, variable and default informations. Some enciclopedias are structured this way too. Example : The dog Default information genus : mammal manifestation : barks behaviour : domestic Fix information # members : 4 paws Variable information Color : Name : Interaction homme-ordinateur
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Memory processes Information aquisition and learning ●
Senses role
●
Time to learn
●
Rehearsal
Forgetting = loosing information ●
Decay, age...
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Interference : new information « covers » the old (telephone numbers)
●
Emotional factors
Information retrieval ●
Recall : information is reproduced from memory, after an intellectual effort
●
Recognition : the presentation of information provides the knowledge that it has
been seen (heared, experienced) before
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