Human Cognitive Abilities                      CS 160                     Fall 1998              Professor James Landay9/1...
Interface Hall of Shame or Fame?For setting cache size in MS InternetExplorer (since changed)Slider from 1% to 100%9/15/98...
Interface Hall of Shame or Fame?What if you have a big disk? (e.g., 4GB * forced to have at least a 40MB cache * takes awa...
Human Cognitive Abilities                      CS 160                     Fall 1998              Professor James Landay9/1...
OutlineReviewModels of human performanceModel human processor (MHP)AdministriviaPerceptionMemory9/15/98                   ...
ReviewColor can be helpful, but easily misusedWhy do we have problems with blue? * less blue photoreceptors * almost none ...
Why Model Human Performance?To test understandingTo predict influence of new technology9/15/98                          7
Engineering Models of Human             PerformancePredictiveQuantitative *   time to perform *   time to learn *   number...
The Model Human Processor   Developed by Card, Moran, & Newell (‘83)                                Long-term Memory      ...
What is missing from MHP?Haptic memory * for touchMoving from sensory memory to WM * attention filters stimuli & passes to...
MHP BasicsBased on empirical dataThree interacting subsystems * perceptual, motor, cognitiveSometimes serial, sometimes pa...
MemoryWorking memory (short term) * small capacity (7 ± 2 “chunks”)     + 6174591765 vs. (617) 459-1765     + DECIBMGMC vs...
MHP Principles of OperationRecognize-Act Cycle of the CP * on each cycle contents in WM initiate actions   associatively l...
The Model Human Processor   Developed by Card, Moran, & Newell (‘83)                                Long-term Memory      ...
Principles of Operation (cont.)Variable Cog. Processor Rate Principle * CP cycle time Tc is shorter when greater effort * ...
Principles of Operation (cont.)Fitts’ Law * moving hand is a series of microcorrections     + correction takes Tp + Tc + T...
Fitts’ Law Example  Pop-up Linear Menu          Pop-up Pie Menu         Today         Sunday        Monday        Tuesday ...
Principles of Operation (cont.)Power Law of Practice * task time on the nth trial follows a power law    + Tn = T1 n-a, wh...
AdministrivaOn-line assignment turn-in * no FTP * for now come FTP in NT lab * looking for good site grabberNew version of...
PerceptionStimuli that occur within one PP cycle fuseinto a single concept * movies (frame rate)     + Frame rate > 1 / Tp...
Perceptual Causality    How fast does 2nd ball need to move?     * must move in < Tp (100 msec)9/15/98                    ...
Simple ExperimentVolunteerStart saying colors you see in list of words* when slide comes up* as fast as you canSay “done” ...
PapelHogarEspaldaCalendarioPaginaCambio
AzulRojoNegroBlancoVerdeAmarillo
MemoryInterference * two strong cues in working memory * link to different chunks in long term memoryWhy learn about memor...
Stage TheoryWorking memory is small * temporary storage     + decay     + displacementMaintenance rehearsal * rote repetit...
Stage Theory                          maintenance                           rehearsal      Sensory        Working        L...
ElaborationRelate new material to already learnedmaterialRecodes informationAttach meaning (make a story) * e.g., sentence...
LTM Forgetting Causes for not remembering an item? 1) never stored: encoding failure 2) gone from storage: storage failure...
Recognition over RecallRecall * info reproduced from memoryRecognition * presentation of info provides knowledge that info...
Facilitating Retrieval: CuesAny stimulus that improves retrieval * example: giving hints * other examples in software?    ...
SummaryMHP * three interacting subsystems?     + perceptual, motor, cognitive * sometimes serial, sometimes parallel * par...
Summary (cont.)Memory * three types?     + sensor, WM, & LTM * use cues in ? to get to ?     + WM -> LTM * interference ca...
Next TimeDiscussion * Interaction Styles in discussion on Wed.     + read Dix 3.5-3.6, 3.8-3.10Lecture * Low-fidelity prot...
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Cognitive abilities[1]

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Cognitive abilities[1]

  1. 1. Human Cognitive Abilities CS 160 Fall 1998 Professor James Landay9/15/98 1
  2. 2. Interface Hall of Shame or Fame?For setting cache size in MS InternetExplorer (since changed)Slider from 1% to 100%9/15/98 2
  3. 3. Interface Hall of Shame or Fame?What if you have a big disk? (e.g., 4GB * forced to have at least a 40MB cache * takes away control from the userWhat if they don’t know their disk size?9/15/98 3
  4. 4. Human Cognitive Abilities CS 160 Fall 1998 Professor James Landay9/15/98 4
  5. 5. OutlineReviewModels of human performanceModel human processor (MHP)AdministriviaPerceptionMemory9/15/98 5
  6. 6. ReviewColor can be helpful, but easily misusedWhy do we have problems with blue? * less blue photoreceptors * almost none in the center of the retina (focus) * brightness determines edges + blue not used for brightness * gets even worse with ageColor deficiency? * red-green or different photopigment response9/15/98 6
  7. 7. Why Model Human Performance?To test understandingTo predict influence of new technology9/15/98 7
  8. 8. Engineering Models of Human PerformancePredictiveQuantitative * time to perform * time to learn * number and type of errors * time to recover from errorsLearnable & usable by systems designersUsefully approximate9/15/98 8
  9. 9. The Model Human Processor Developed by Card, Moran, & Newell (‘83) Long-term Memory Working Memory sensory Visual Image Auditory Image buffers Store Store (Dix)Eyes Perceptual Motor Cognitive Processor Processor ProcessorEars 9/15/98 Fingers, etc. 9
  10. 10. What is missing from MHP?Haptic memory * for touchMoving from sensory memory to WM * attention filters stimuli & passes to WMMoving from WM to LTM * rehearsel9/15/98 10
  11. 11. MHP BasicsBased on empirical dataThree interacting subsystems * perceptual, motor, cognitiveSometimes serial, sometimes parallel * serial in action & parallel in recognition + pressing key in response to light + driving, reading signs, & hearing at onceParameters * processors have cycle time (T) ~ 100-200 ms * memories have capacity, decay time, & type9/15/98 11
  12. 12. MemoryWorking 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 secondsLong-term memory * episodic & semantic * huge (if not “unlimited”) * slower access time (~100 ms) w/ little decay9/15/98 12
  13. 13. MHP Principles of OperationRecognize-Act Cycle of the CP * on each cycle contents in WM initiate actions associatively linked to them in LTM * actions modify the contents of WMDiscrimination Principle * retrieval is determined by candidates that exist in memory relative to retrieval cues * interference by strongly activated chunks9/15/98 13
  14. 14. The Model Human Processor Developed by Card, Moran, & Newell (‘83) Long-term Memory Working Memory sensory Visual Image Auditory Image buffers Store Store (Dix)Eyes Perceptual Motor Cognitive Processor Processor ProcessorEars 9/15/98 Fingers, etc. 14
  15. 15. 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 practice9/15/98 15
  16. 16. Principles of Operation (cont.)Fitts’ Law * moving hand is a series of microcorrections + 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 required9/15/98 16
  17. 17. Fitts’ Law Example Pop-up Linear Menu Pop-up Pie Menu Today Sunday Monday Tuesday Wednesday Thursday Friday SaturdayWhich will be faster on average? * pie menu (bigger targets & less distance)9/15/98 17
  18. 18. Principles of Operation (cont.)Power Law of Practice * task time on the nth trial follows a power law + Tn = T1 n-a, where a = .4 + i.e., you get faster the more times you do it! + applies to skilled behavior (sensory & motor) + does not apply to knowledge acquisition or qualityRationality Principle * people act to attain goals through rational action + Goals + Task + Operations + Info. Inputs + Knowledge + Process-limits -> Behavior9/15/98 18
  19. 19. AdministrivaOn-line assignment turn-in * no FTP * for now come FTP in NT lab * looking for good site grabberNew version of NotePals client * notes are visible to “group” by default (not public) + groups are your project teamsQuestions on homework? * tasks don’t have to use “formal” style of book * lots of stuff on Club CS1609/15/98 19
  20. 20. PerceptionStimuli that occur within one PP cycle fuseinto a single concept * movies (frame rate) + Frame rate > 1 / Tp = 1/(100 msec/frame) = 10 f/sec * morse code listening ratePerceptual causality * two distinct stimuli can fuse if the first event appears to cause the other * events must occur in the same cycle9/15/98 20
  21. 21. Perceptual Causality How fast does 2nd ball need to move? * must move in < Tp (100 msec)9/15/98 21
  22. 22. Simple ExperimentVolunteerStart saying colors you see in list of words* when slide comes up* as fast as you canSay “done” when finished9/15/98 22
  23. 23. PapelHogarEspaldaCalendarioPaginaCambio
  24. 24. AzulRojoNegroBlancoVerdeAmarillo
  25. 25. MemoryInterference * two strong cues in working memory * link to different chunks in long term memoryWhy learn about memory? * know what’s behind many HCI techniques * helps you understand what users will “get” * aging population of users9/15/98 25
  26. 26. Stage TheoryWorking memory is small * temporary storage + decay + displacementMaintenance rehearsal * rote repetition * not enough to learn information wellAnswer to problem is organization * Faith Age Cold Idea Value Past Large * In a show of faith, the cold boy ran past the church9/15/98 26
  27. 27. Stage Theory maintenance rehearsal Sensory Working Long Term Image Store Memory Memory decay decay, decay? displacement interference? chunking / elaboration9/15/98 27
  28. 28. ElaborationRelate new material to already learnedmaterialRecodes informationAttach meaning (make a story) * e.g., sentencesVisual imageryOrganize (chunking)Link to existing knowledge, categories9/15/98 28
  29. 29. 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 Interference model of forgetting * one item reduces ability to retrieve another * proactive interference (3) + earlier learning reduces ability to retrieve later info. * retroactive interference (3 & 2) + later learning reduces the ability to retrieve9/15/98earlier info. 29
  30. 30. Recognition over RecallRecall * info reproduced from memoryRecognition * presentation of info provides knowledge that info has been seen before * easier because of cues to retrieval9/15/98 30
  31. 31. Facilitating Retrieval: CuesAny 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 learnedCan Facilitate memory in any systemWhat are we taking advantage of? * recognition over recall!9/15/98 31
  32. 32. SummaryMHP * three interacting subsystems? + perceptual, motor, cognitive * sometimes serial, sometimes parallel * parameters? + processors have cycle time (T) + memories have capacity, decay time, and type * ten principles of operation (we showed 6)Perceive distinct events in same cycle as one9/15/98 32
  33. 33. Summary (cont.)Memory * three types? + sensor, WM, & LTM * use cues in ? to get to ? + WM -> LTM * interference can make hard to access? + LTMCues can make it easier to access LTM9/15/98 33
  34. 34. Next TimeDiscussion * Interaction Styles in discussion on Wed. + read Dix 3.5-3.6, 3.8-3.10Lecture * Low-fidelity prototyping / Wizard of Oz + read article by Rettig (need for next assignment) + also online but very slow, will put up a link to the color pictures9/15/98 34
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