Efficiency Flashcards

1
Q

Chunking

A
  • Chunk is a unit of memory or perception:
  • Define symbols and activation of past experience
  • Depends on both presentation and what we already know
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2
Q

Working Memory

A
  • Where you do your conscious thinking:
  • not separate in the brain
  • Capacity of working memory:
  • Small 4+/-1 chunks
  • A good UI wont put heavy demands on users working memory
  • Data put in working memory disappears in a short time:
  • Short lived: around 10 secs
  • Maintenance rehearsal - repeating the items to yourself fends off decay
  • Elaborative rehearsal - make connections with existing chunks
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3
Q

Improve Efficiency of Output 1

A
  • Our ability to form chunks in working memory:
  • how the information is presented
  • what we already know
  • Present information in easily recognised chunks
  • Efficiency slide 15 pic
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4
Q

Improve Efficiency of Output 2

A
  • Take advantage of this as a desinger:
  • dont present info as long as long undifferentiated strings of random characters or numbers
  • break them up into 3- or 4- character groups
  • find a way to make the chunks more familiar
  • Not just to random numbers or hashes but to all kinds of data
  • Efficiency slide 15 pic
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5
Q

Pointing: Fitts’s Flaw

A
  • Fundamental law of human sensory motor system
  • Time T to move your hand to target of size S at distance D away is (RT, MT)
  • T =RT +MT = a+b log (D/S + 1)
  • Depends on index of difficult log (D/S + 1)
  • Using a mouse to point at a target on a screen
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6
Q

Implications of Fitts’s Law 1

A
  • Targets at screen edge are easy to hit
  • Because it acts as a target with an infinite size
  • Edge of screen real estate is precious
  • Mac menubar beats windows menubar
  • Unclickable margins are foolish
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7
Q

Implications of Fitts’s Law 2

A
  • Linear pop ip vs pie menus:
  • not widely used
  • external consistency
  • layout simplicty
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8
Q

Improve Mouse Efficiency 1

A
  • Make frequently used targets big:
  • Size matters for Fitts’s law
  • The bigger the target the easier the pointing task is
  • Put targets used together near each other
  • Use screen corners and edges
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9
Q

Mouse Movements: Steering Tasks

A
  • Time T to move your hand through a tunnel of length D and width S is:
  • T = a+b D/S
  • Safety presentation slide 5
  • Index of difficult is now linear not logarithmic:
  • So steering is much harder than pointing
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10
Q

Invisible Triangular Zone

A
  • Pointing straight to submenu without unusual corrections
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11
Q

Improve Mouse Efficiency 2

A
  • Avoid steering whenever possible
  • When you cant avoid it, minimise steering distance
  • Cascading submenus are much worse when the menu items long
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12
Q

Predictive Evaluation

A
  • How we can predict the efficiency of a UI before we build it:
  • Predictive evaluation uses an engineering model of human cognition to predict usability
  • E.g. deleting a word
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13
Q

Keyboard Shortcuts

A
  • Ctrl C and V
  • Pending delete
  • Keyboard comments:
  • Easily memorable key combos
  • Accessibility benefits (users that cant see well)
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14
Q

Defaults and pending Delete

A
  • Safety slide 12
  • Common answers already filled into a form:
  • Provide shortcuts to both novices and frequent users
  • having the default costs nothing
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15
Q

History

A
  • Offer recently used or frequently used choices:
  • Making file opening more difficult
  • Keep histories of user’s previous choices, not just files but of any values that might be useful e.g. Open recent
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16
Q

Autocomplete

A
  • Minimises typing

- Helps with efficiency and safety

17
Q

Aggregation

A
  • Adds efficiency
  • User can collect number of items and handle them all at once
  • e.g. ticking boxes of list of emails then pressing delete in hotmail
18
Q

Anticipation

A
  • Put all needed info and tools for a particular task within user’s easy reach
  • increases learnability (user doesn’t have to learn about other places to perform task)
  • Increases efficiency (even if other places are known you arent force to navigate to the to get the job done
  • Operations are available elsewhere in windows