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
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
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
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
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
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
7
Q
Implications of Fitts’s Law 2
A
- Linear pop ip vs pie menus:
- not widely used
- external consistency
- layout simplicty
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
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
10
Q
Invisible Triangular Zone
A
- Pointing straight to submenu without unusual corrections
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
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
13
Q
Keyboard Shortcuts
A
- Ctrl C and V
- Pending delete
- Keyboard comments:
- Easily memorable key combos
- Accessibility benefits (users that cant see well)
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
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
