lecture 2: usability
TRANSCRIPT
CMSC 434 Introduction to Human Computer Interaction Spring 2010 1
Lecture 2: Usability
January 27
CMSC 434 Introduction to Human Computer Interaction Spring 2010 2
What is Usability?
• How easy is it for users to perform a particular task using a system or device?
• How well a system or device can support the users to perform a particular task?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 3
Usability of doors
1. Why do door knobs always turn the same direction to open?
2. Why do door knobs installed at waist height? 3. Why do some people rather use a small side
door next to a large revolving door? 4. Why do some doors have knobs, some bars? 5. Why do doors have dampers and closers? 6. Why do doors have see through windows? 7. Why do doors lock only from outside with keys? 8. Why do people decorate doors?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 4
Five attributes of usability
• Easy to learn • Efficient to use • Easy to remember • Few user errors • Subjectively pleasing
CMSC 434 Introduction to Human Computer Interaction Spring 2010 5
CMSC 434 Introduction to Human Computer Interaction Spring 2010 6
CMSC 434 Introduction to Human Computer Interaction Spring 2010 7
CMSC 434 Introduction to Human Computer Interaction Spring 2010 8
CMSC 434 Introduction to Human Computer Interaction Spring 2010 9
CMSC 434 Introduction to Human Computer Interaction Spring 2010 10
Five attributes of usability
• Easy to learn • Efficient to use • Easy to remember • Few user errors • Subjectively pleasing
CMSC 434 Introduction to Human Computer Interaction Spring 2010 11
Three aspects of HCI
• Design • Evaluation • Implementation
CMSC 434 Introduction to Human Computer Interaction Spring 2010 12
1. Easy to learn
• Evaluation – Can users learn to perform the correct
interactions?
• Design – How can we provide the right guidance to
help users learn the interactions easily?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 13
CMSC 434 Introduction to Human Computer Interaction Spring 2010 14
2. Efficient to use
• Evaluation – How fast can users perform the correct
interactions?
• Design – How can we optimize the interface design
for faster interactions?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 15
CMSC 434 Introduction to Human Computer Interaction Spring 2010 16
3. Easy to remember
• Evaluation – Can users remember the correct
interactions?
• Design – What reminders can we provide to help
users remember the correct interactions?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 17
CMSC 434 Introduction to Human Computer Interaction Spring 2010 18
4. Few user errors
• Evaluation – Is it likely or unlikely for users to make
interaction errors by accident?
• Design – How can we identify and eliminate design
elements prone to user accidents?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 19
CMSC 434 Introduction to Human Computer Interaction Spring 2010 20
5. Subjectively pleasing
• Evaluation – Are users pleased with the way they interact
with the system?
• Design – How do we introduce design features to
reduce stress and increase satisfaction?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 21
CMSC 434 Introduction to Human Computer Interaction Spring 2010 22
People complain about usability problems
Real users’ complaints about VLC Player (1/2) • Hard-to-guess shortcuts to operate with the
movie. • Non-responsive shortcuts in WX interface. • Unresponsive stop/play. • Preferences are way too big. You can navigate
thru them all the day long and you won't find what you're really looking for.
(cont…)
CMSC 434 Introduction to Human Computer Interaction Spring 2010 23
People complain about usability problems
Real users’ complaints about VLC Player (2/2) • Hard to remember what filters have been
enabled. • Adding/removing a video filter during
playback often causes video window to resize.
• The fullscreen mode is always left between two videos, which is annoying when using playlists. It should only be disabled manually.
CMSC 434 Introduction to Human Computer Interaction Spring 2010 24
Usability Engineering
• Focus on assessing and making recommendations to improve usability
• Research and design process that ensures a product with good usability
CMSC 434 Introduction to Human Computer Interaction Spring 2010 25
Benefits of usability engineering to companies
• Increase customer satisfaction • Increase sales and revenues • Reduce development time and costs • Reduce maintenance costs • Decrease training and support costs
Example: IBM
CMSC 434 Introduction to Human Computer Interaction Spring 2010 26
A day in life of a usability engineer
Lani Hathway at EA Sports (1/2) • Interview project team members about
their product, usability concerns, design process
• Attend team meetings on strategy, feature design, schedule, and other hot topics
• Help teams set usability goals (cont...)
CMSC 434 Introduction to Human Computer Interaction Spring 2010 27
A day in life of a usability engineer
Lani Hathway at EA Sports (2/2) • Drive user research activities such as
gathering data for creating user personas, task lists and scenarios
• Design usability tests • Present results from usability tests and
other user research to project teams • Summarize results from usability tests
into design guidelines or style guides
CMSC 434 Introduction to Human Computer Interaction Spring 2010 28
Usability is relative to
• Users • Tasks • Locations • Time
CMSC 434 Introduction to Human Computer Interaction Spring 2010 29
Five attributes of usability
Usability
Utility
Usefulness Few errors
Memorizability
Learnbility
Efficiency
Satisfaction Practical acceptability
Speed
Security
Reliability
Cost
Size
Social acceptability
System acceptability
CMSC 434 Introduction to Human Computer Interaction Spring 2010 30
The new iMac • LED backlighting • More pixels, better picture • Stunning from every angle • Quad-core power • Revved-up graphics • More memory and storage • Built-in Wi-Fi • Wireless keyboard • iSight • The world’s first multi-touch mouse • Ports for everything • Wall mountable
CMSC 434 Introduction to Human Computer Interaction Spring 2010 31
Tradeoffs
• Usability attributes – Efficient or easy to learn – Efficient or robust to user errors – Easy to learn or easy to remember
• User groups – Experts or novices
• Tasks – Reading, typing, coding or drawing
CMSC 434 Introduction to Human Computer Interaction Spring 2010 32
Activity: Me vs. Users
1. IDE or Command line? 2. Default or personalization? 3. On-access or on-demand virus scan? 4. Show or hide captions? 5. Folders or search? 6. Speed or stamina? 7. Browser default page?
CMSC 434 Introduction to Human Computer Interaction Spring 2010 33
What are the usability tradeoffs of these keyboard designs?
Multi-tap Keyboard Slideout Keyboard Touchscreen
CMSC 434 Introduction to Human Computer Interaction Spring 2010 34
• Homework: Implementation 1 – Due next Monday (2/1)
• Micro homework: take a picture of a door – The one you used more often. – The one you think should be fixed.
• Project: Preferences – Due next Monday (2/1) – Choose from three possible themes
• Design for improving health • Design for a special user population • Redesign a bad website
CMSC 434 Introduction to Human Computer Interaction Spring 2010 35
CMSC 434 Introduction to Human Computer Interaction Spring 2010 36
CMSC 434 Introduction to Human Computer Interaction Spring 2010 37
Activity: Amazon Reviews