cognitive models
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Cognitive Models. CS 160, Spring 2004 February 18. Why Model Human Performance?. To test understanding To predict influence of new technology. Model Human Processor. What is missing from MHP?. Haptic memory For touch Moving from sensory memory to WM - PowerPoint PPT PresentationTRANSCRIPT
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Cognitive Models
CS 160, Spring 2004February 18
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Why Model Human Performance?
To test understanding To predict influence of new
technology
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Model Human Processor
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What is missing from MHP?
Haptic memory* For touch
Moving from sensory memory to WM* Attention filters stimuli & passes to WM
Moving from WM to LTM* Rehearsal
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MHP Basics
Based on empirical data* Years of basic psychology experiments in the
literature
Three interacting subsystems* Perceptual, motor, cognitive
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MHP Basics
Sometimes serial, sometimes parallel* Serial in action & parallel in recognition
+Pressing key in response to light+Driving, reading signs, & hearing at once
Parameters* Processors have cycle time (T) ~ 100-200 ms* Memories have capacity, decay time, & type
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Memory
Working memory (short term)* Small capacity (7 ± 2 “chunks”)
+6174591765 vs. (617) 459-1765+DECIBMGMC vs. DEC IBM GMC
* Rapid access (~ 70ms) & decay (~200 ms)+pass to LTM after a few seconds
Long-term memory* Huge (if not “unlimited”)* Slower access time (~100 ms) w/ little decay
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MHP Principles of Operation
Recognize-Act Cycle of the CP* On each cycle contents in WM initiate actions
associatively linked to them in LTM* Actions modify the contents of WM
Discrimination Principle* Retrieval is determined by candidates that
exist in memory relative to retrieval cues* Interference by strongly activated chunks
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The Model Human Processor
Long-term Memory
Working MemoryVisual Image
StoreAuditory Image
Store
PerceptualProcessor
CognitiveProcessor
MotorProcessor
Eyes
Ears
Fingers, etc.
sensorybuffers
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Principles of Operation (cont.)
Variable Cog. Processor Rate Principle* CP cycle time Tc is shorter when greater effort
* Induced by increased task demands/information
* Decreases with practice
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Principles of Operation (cont.)
Fitts’ Law* Moving hand is a series of microcorrections,
each correction takes Tp + Tc + Tm = 240 msec
* Time Tpos to move the hand to target size S which is distance D away is given by: Tpos = a + b log2 (D/S + 1)
Summary* Time to move the hand depends only on the
relative precision required
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Fitts’ Law Example
Which will be faster on average?
TodaySundayMondayTuesday
WednesdayThursday
FridaySaturday
Pop-up Linear Menu
Pop-up Pie Menu
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Fitts’ Law Example
Pie menu: bigger targets for a given distance; 6.2 / k vs. 2 / k
TodaySundayMondayTuesday
WednesdayThursday
FridaySaturday
Pop-up Linear Menu
Pop-up Pie Menu
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Pie Menus
Pie menus have proven advantages, but you rarely see them (QWERTY phenomenon?).
Examples: Maya (animation tool), and many research systems like DENIM.
Still, open-source code for them exists.
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Principles of Operation (cont.)
Power Law of Practice* Task time on the nth trial follows a power law
Tn = T1 n-a + c, where a = .4, c = limiting constant
* i.e., you get faster the more times you do it!* Applies to skilled behavior (sensory & motor)* Does not apply to knowledge acquisition or
quality
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Power Law of Practice
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Perception
Stimuli that occur within one PP cycle fuse into a single concept* Frame rate necessary for movies to look real?
+time for 1 frame < Tp (100 msec) -> 10 frame/sec.
* Max. morse code rate can be similarly calculated
Perceptual causality* Two distinct stimuli can fuse if the first event
appears to cause the other* Events must occur in the same cycle
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Perceptual Causality
How soon must red ball move after cue ball collides with it?
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Perceptual Causality
Must move in < Tp (100 msec)
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Perceptual Causality
Must move in < Tp (100 msec)
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Break
Administrivia: Midterm is a week from Friday.* Material covered up to this Friday.* Closed book
In-class quizzes will start this week.
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Simple Experiment
Volunteer Start saying colors you see in list of
words* When slide comes up* As fast as you can
Say “done” when finished Everyone else time it…
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PaperHomeBackSchedulePageChange
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Simple Experiment
Do it again Say “done” when finished
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BlueRedBlackWhiteGreenYellow
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Memory
Interference* Two strong cues in working memory* Link to different chunks in long term memory
Why learn about memory?* Know what’s behind many HCI techniques* Helps you understand what users will “get”* Lots of people have memory difficulties
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Stage Theory
Working memory is small* Temporary storage
+decay+displacement
Maintenance rehearsal* Rote repetition* Not enough to learn information well
Answer to problem is organization* Faith Age Cold Idea Value Past Large* In a show of faith, the cold boy ran past the
church
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Stage Theory
Working Memory
Sensory Image Store
Long Term Memory
decay decay,displacement
chunking / elaboration
decay?interference?
maintenancerehearsal
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Elaboration
Relate new material to already learned material
Recodes information Attach meaning (make a story)
* e.g., sentences
Visual imagery Organize (chunking) Link to existing knowledge, categories
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LTM Forgetting
Causes for not remembering an item?* 1) Never stored: encoding failure* 2) Gone from storage: storage failure* 3) Can’t get out of storage: retrieval failure
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LTM Forgetting
Interference model of forgetting* One item reduces ability to retrieve another* Proactive interference
+earlier learning reduces ability to retrieve later info.
* Retroactive interference +later learning reduces the ability to
retrieve earlier info.
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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
We want to design UIs that rely on recognition!
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Facilitating Retrieval: Cues
Any stimulus that improves retrieval* Example: giving hints* Other examples in software?
+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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Summary
MHP: three interacting subsystems* Perceptual, motor, cognitive* Sometimes serial, sometimes parallel* We gave several principles of operation
Memory principles:* Several types: WM -> LTM progression* Interference causes recognition problems* Recognition over Recall