Lecture 2: Usability. January 27

Transcription

1 Lecture 2: Usability January 27 1

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? 2

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? 3

4 Five attributes of usability Easy to learn Efficient to use Easy to remember Few user errors Subjectively pleasing 4

5 Spring 2010 CMSC 434 Introduction to Human Computer Interaction 5

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10 Five attributes of usability Easy to learn Efficient to use Easy to remember Few user errors Subjectively pleasing 10

11 Three aspects of HCI Design Evaluation Implementation 11

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? 12

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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? 14

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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? 16

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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? 18

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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? 20

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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 ) 22

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. 23

24 Usability Engineering Focus on assessing and making recommendations to improve usability Research and design process that ensures a product with good usability 24

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 25

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...) 26

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 27

28 Usability is relative to Users Tasks Locations Time 28

29 Five attributes of usability System acceptability Social acceptability Practical acceptability Usefulness Security Cost Speed Size Reliability Usability Utility Learnbility Memorizability Few errors Efficiency Satisfaction 29

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 30

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 31

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? 32

33 What are the usability tradeoffs of these keyboard designs? Multi-tap Keyboard Slideout Keyboard Touchscreen 33

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 34

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37 Activity: Amazon Reviews 37