1. CMPUT 301: Lecture 17 Usability Paradigms and Principles Lecturer: Martin Jagersand Department of Computing Science University of Alberta Notes based on previous courses by Ken Wong, Eleni Stroulia Zach Dodds, Martin Jagersand

2. 2 Problems Development: How can we ensure the usability of an interactive system as we develop it? Evaluation: How can the usability of an interactive system be demonstrated or measured?

3. 3 Solutions Two complementary approaches: –paradigms –see successful examples as inspiration for future development –principles –derive theories for effective interaction using knowledge of sensory and perceptual psychology, sociology, and computing

4. 4 Approaches Paradigms 1.specific 2.technology driven 3.not well defined 4.practical Principles 1.General (applies whenever humans interact with each other or machines) 2.technology independent 3.Repeatable 4.Based on theory

5. 5 Paradigms Time-sharing: –40’s and 50’s: increasing computing power –Several users share the computing power of one central machine –shift from batch to interactive use –provide each user the illusion of a full computer –Unix [Dennis Ritchie et al. 1969 (Bell Labs)] –VM360,70,90 and CMS (IBM)

6. 6 Paradigms Video display units: –50’s 60’s –Display data as graphics –shift away from tty paper printouts Sketchpad [Ivan Sutherland 1962 (MIT)] –interact with visual objects to modify computer memory. –Visual-motor manipulation versus coding

7. 7 Paradigms Sketchpad: –light pen and 9” cathode ray tube –ran on 320 K RAM –user manipulates geometric shapes –object-oriented language –hierarchical structures –Spatial organization and saliency

8. 8 Paradigms Integrated environments: –use computers to enhance human solving of complex problems. –Assume naive human (revolutionary; at the time only experts used computers) –provide the right toolkit by composing the right tools (Carpenter analogy: re-uses tools) –NLS (oNLine System) [Douglas Englebart 1968 (SRI)]

9. 9 Paradigms oN Line System: –mouse, chording keyboard, high-resolution display –integrated, configurable, graphical environment –online word and outline editing –hypertext linking –electronic messaging –video conferencing

10. 10 Paradigms Short-sighted: I think there is a world market out there for maybe five computers. — Thomas Watson, chairman of IBM, 1943 There is no reason anyone would want a computer in their home. — Ken Olson, founder of DEC, 1977 Remember: Early days computers were used either for scientific calculations or by governments to keep track of individuals

11. 11 Paradigms Visionary: The best way to predict the future is to invent it. — Alan Kay

12. 12 Paradigms Personal computing: –computing for everyone (not just the intellectual elite) Papert: –Logo Alan Kay 1969 (U Utah) –Vision of Dynabook –Smalltalk

13. 13 Paradigms Dynabook: –cardboard prototype –portable and robust –touch screen –wireless –graphical user interface –so simple, a child could use it

14. 14 Paradigms Xerox PARC: –Smalltalk –object oriented language and environment –Ethernet –standard, layered communications protocols –client/server architecture –decentralized computing –laser printing –seamlessly transfer digital documents to paper

15. 15 Paradigms The metaphor: –use metaphors to teach new concepts –e.g., desktop metaphor for filing tasks, file, folder. –Note: precedes graphic desktop interfaces (Windows) –metaphors can only go so far –e.g., trash can, floppy disks, hard drives, etc. –non-intuitive situations –e.g., dragging floppy to trash to eject (Mac) –cultural bias

16. 16 Paradigms WIMP user interface: –put user in temporal control over the program –allow humans to switch/resume contexts –contexts are shown in windows

17. 17 Paradigms Early WIMP: –Alto –[Xerox PARC 1970s] –Star –[Xerox 1981] ($15000)

18. 18 Paradigms Early WIMP: –Lisa –[Apple, 1983] ($10000) –Macintosh –[Apple, 1984] ($2500)

19. 19 Paradigms Direct manipulation: (Schneiderman ’82) –visibility of the objects of interest –i.e., recognition, not recall –incremental action with rapid feedback –e.g., rubberbanding –reversible actions (undo) –i.e., encourage safe exploration –every choosable action is legal –e.g., graying out invalid choices –manipulation of objects directly –i.e., instead of command line –Needs high bandwidth interaction with human.

20. 20 Paradigms WYSIWYG: –what you see is what you get –minimize the difference between onscreen presentation and final printed product –not a panacea for usability –versus markup languages? Related to direct manipulation

21. 21 Paradigms Language versus action: –complicated, repetitive tasks are often tedious to do via direct manipulation –e.g., renaming the suffix of a group of files –use a scripting language as a kind of intermediary between the user and system –i.e., programmable, recordable, attachable –e.g., program by example

22. 22 Paradigms Hypertext: –authoring, navigating, and reading linked, non- linear information –Memex proposal [Vannevar Bush 1945] “As We May Think” –hypertext [Ted Nelson 1965 (Harvard U)]

23. 23 Paradigms Memex: –an information storage and retrieval “desk” –linking, indexing, annotation, trails –enhance human memory and associative capacity

24. 24 Paradigms Multi-modality: –use multiple human communication channels –combine visual, audio, and haptic channels (in better ways than through keyboard and VDU. Note that as humans we are always multimodal) –e.g., sound effects, notification, force feedback

25. 25 Paradigms CSCW: –computer supported cooperative work –network computers together to support human collaboration –asynchronous or synchronous –e.g., email, videoconferencing

26. 26 Paradigms The World Wide Web: –merging of hypertext, networking, and personal computing –Internet [1969 (DARPA et al.)] –WWW [Tim Berners-Lee 1989 (CERN)] –Mosaic web browser [Marc Andreesen 1993 (NCSA)]

27. 27 Paradigms Agent-based interfaces: –software agents act on the behalf of users –More than a direct command -> action mapping –e.g., email filtering agents, web crawlers

28. 28 Paradigms Ubiquitous computing: –computers are everywhere, but become no longer noticeable –electric motor analogy –utility  ubiquity  invisibility –special devices versus general devices –ubiquitous computing [Mark Weiser 1991 (Xerox PARC)]

29. 29 Paradigms Scales of computing: –yard-sized –e.g., SMART Board –foot-sized –e.g., tablet computer –inch-sized –e.g., Palm Pilot, electronic Post-Its?

30. 30 Paradigms Future?: –emerging technologies –wireless networking –voice recognition –pen-based computing –wearable computing –vision systems –biometrics –etc.

31. 31 Paradigms Future?: –moving from the traditional desktop to a “smart” environment –interacting in multiple modes: keyboard, voice, gesture, etc.

32. 32 End What did I learn today? What questions do I still have?