2_Usability.pdf

Usability Introduction to HCI Hasti Seifi Arizona State University  2 A2: Find a Group Each group needs 5 members A Google sheet for help with group formation Link posted in A2 description...

Usability Introduction to HCI Hasti Seifi Arizona State University  2 A2: Find a Group Each group needs 5 members A Google sheet for help with group formation Link posted in A2 description Contact people directly to make a group Contact your TA if you face dif culty ([email protected]) fi  3 Future Assignments A2- Team and Project Proposal Select a topic A3- Human Capabilities A4- Analysing users and their tasks A5- Creating and evaluating paper prototypes A6- Making digital prototypes A7- Heuristic evaluation A8- User testing A9- Design for emerging interfaces A10- Portfolio preparation  4 A2: What is a good topic? A n unsup ported ac tivit y or h um an need The solution can be a mobile app or website Involves a t l e a s t 4 - 5 t a s k s, more than 1-2 screen Yo u c a n a c c e s s t h e r e a l u s e r s It is ok to redesign an existing interface/app, but the redesign should be about new tasks/functionality rather than how the interface looks N O T E: Topics that are the same as previous semesters will be rejected. Good examples Bad examples A system for students to carpool Authentication system by eye colour A collaborative DJing interface for parties Redesign Slack to show number of views A system for checking food allergies during grocery shopping A communication system for airplane pilots  5 User Task vs. Interface Feature U s e r t a s k is about WHAT the user needs or wants to be able to do. C a n b e i m p l e m e n t e d i n d i ff e r e n t w a y s , s o i n d e p e n d e n t o f s o l u t i o n Ta sk exampl e: “u s er w an t s t o h a v e a r e c ip e f o r in g r e d ie n t s t h e y have” Interface feature is about H O W to support or implement a solution to su ppo rt th e us er task. E xa mpl e of fea ture s “a sea rch fu nct io n f or r ec ip es ” “fil te rs to narrow dow n an d sor t r ec ipes ” “an A I agen t that c r ea t e s n ew r ec ipes ” Av o i d p r o p o s i n g a n i n te r fa c e /s o l u ti o n ( n o i m a g e s o f i n te r fa c e a t a l l )  6 A2: Example Topics from Previous Semesters Yo u c a n a c c e s s i t o n C a n v a s a n d i n A 2 d e s c r i p t i o n.  7 Lear ning Objectives 1. Understand why human-centred interaction design matters 2. Identify main elements of usability 3. A n a l y z e u s a b i l i t y o f a n i n t e r a c t i v e s y s t e m  Interaction Design: Why? From expert users to everyone Mainframe Personal Ubiquitous Computer Computer Computing 1960s 1980s Now  Interaction Design: Why? From expert users to everyone Changing user interfaces XeroxStar Apple iBooks 1981 2012  Interaction Design: Why? From expert users to everyone Changing user interfaces The cost/benefit argument “The rule of thumb in many usability-aware organizations is that the cost-benefit ratio for usability is $1:$10-$100. Once a system is in development, correcting a problem costs 10 times as much as fixing the same problem in design. If the system has been released, it costs 100 times as much relative to fixing in design.” ( To m G il b & Sus an na h Fin z i, Pr i n ci ple s of S of t wa re E n gin e e rin g M an a g em en t  Interaction Design: Why? From expert users to everyone Changing user interfaces The cost/benefit argument S afety reasons Three Main Island: Nuclear accident Author/Copyright holder: John G. Kemeny. Copyright terms and license: Public Domain  12 Three aspects of human-centred design Usabilit y User Experience Acces sib ility  13 Among many! Six usability milestones The design of Fitts’ Law everyday things ISO definition 1954 1988 1998 1937 1985 1993 Model 302 Designing for Usability phone Usability engineering  14 1937 - Model 302 phone Designed by Henry Dreyfuss - pioneer in the field of ergonomics Focus on designing products which accommodate human needs Understand how people interact with objects in the physical world to design for s a f e t y and c o m f o r t (less focus on efficiency) S E E M O R E P R O J E C T S A T C R E A T I V E M A R K E T. C O M / S L I D E P R O  15 1954 - Fitts’ Law Mo d el o f human psychomotor behaviour by Paul Morris Fitts The time required to point a target is a function of the distance to the target and the width of the target  16 1985 - Designing for Usability Three principles of design Earl y fo cus on u se r s a n d t as k s Empi rica l measu r em en t Iterative Design The first desktop was released around 1964  17 1988 - The Design of Everyday Things Wr i t t e n b y D o n N o r m a n ( A p p l e , H P, N i e l s e n N o r m a n G r o u p ) Focus on the interplay between people and technology to make products understandable and usable Search for Norman doors S E E M O R E P R O J E C T S A T C R E A T I V E M A R K E T. C O M / S L I D E P R O  18 1993 - Usability Engineering Wr i t t e n b y J a k o b N i e l s e n Focus on c o s t - e f f e c t i v e m e t h o d s that can be quickly implemented E.g.: H e uris tic e va lua t ion ( gu idelines f or ex per t e v a lu a t i o n ) S E E M O R E P R O J E C T S A T C R E A T I V E M A R K E T. C O M / S L I D E P R O  19 Six usability milestones Usability standard The design of Fitts’ Law everyday things ISO definition 1954 1988 1998 1937 1985 1993 Model 302 Designing for Usability phone Usability engineering  20 Nielsen 1993: What makes people accept and use a c o mp u t e r sy s te m ? Nielsen 1993 - Chapter 2  21 Components of Usability Usability is not a single, one-dimensional property of a user interface. U s a b i l i t y a n a l y s i s o f t e n d e a l s w i t h t h e s e f i ve com p o n e n t s Nielsen 1993 - Chapter 2  22 Easy to Lear n Focus on new users Ideally: learn by exploration How to measure: time to achieve specific level proficiency, time to find a feature  23 Easy to Remember Occasional use H o w t o m e a s u r e : p a s t u s e r w h o h a s b e e n a w a y, l o n g i t u d i n a l s t u d y, memo ry ex peri m en ts  24 Efficient to Use E ffic ien t: low re so urc es ( e. g. , t im e, m ent al load) E xis tin g user o r e x p e r t p e r f o r m a n c e Defining expertise How to measure: time to complete a task No extra steps (or at least let people skip) Reduce repetitive data entry  25 Easy to Lear n vs. Efficient to Use D i ff e r e n c e i n f o c u s i n g o n n o v i c e o r e x p e r t A system can support both A c ce lera tors, d es c r ip t iv e la bels , def ault s , s hor t & lo n g m e n u s  26 Examples of accelerators, … Templates and defaults Keyboard shortcut Activate/deactivate interface elements  Few (Catasrophic) Errors 27 P eop le wi l l mak e e rror s Ty p e s o f e r r o r s , a n d t h e i r c o n s e q u e n c e How to reduce the chance of error? How to reduce impact of errors? How do these examples reduce errors? Which one results in fewer/less severe errors?  Subjectively Pleasing 28 How to measure: user rating, observational metrics, voluntary use, physiological data Risk: user bias  29 Six usability milestones Usability standard The design of Fitts’ Law everyday things ISO definition 1954 1988 1998 1937 1985 1993 Model 302 Designing for Usability phone Usability engineering  30 1998 - ISO Definition of Usability The e f f e c t i v e n e s s , e f f i c i e n c y, a n d satisfaction with which s p e c i f i e d users achieve s p e c i f i e d g o a l s in particular environments Efficiency Effectiveness Satisfaction Nielsen 1993 - Chapter 2  31 Usability: Focus on Users Who is the user of your system? What knowledge and abilities they have? What are their interests?  32 Usability: Focus on tasks Focus on completing a task P eop le h ave goa ls wh en int e r ac t ing wit h s y s t em s D i ff e r e n t u s e r s m i g h t h a v e d i ff e r e n t g o a l s E xa mpl e goal s: p ur c ha se a f lig ht t ic k et f or t wo peo p l e , wa r m u p f o o d , se nd mo ney to a frie nd  33 The Seven Stages of Actions Goals Intention Evaluation of to act interpretations Sequence of Interpreting actions the perception Execution of the Perceiving the action sequence state of the world The World  34 To achieve those goals… … peop le face two gu l f s The gulf of execution The golf of evaluation Goa ls Gulf of exec ution Gu lf of ev alu ation Compu te r Systems  35 Gulf of execution C o n c e r n e d w i t h t r a n s l a t i n g goals into actions D i s c o v e r a b i l i t y: How do I know what I can do? Does the system provide actions that correspond to the intentions of the user? Goals Gulf of exec ution Compu ter Systems  36 Gulf of evaluation Concerned with deciding whether actions were successful Feedback : “Does the system provide a physical representation that can b e directly perceived and that it is directly interpretable in terms of the intentions and expectations of the person?” [Norman, 1988] Goals Gu lf of ev alu ation Compu ter Systems  37 Discuss with your neighbour or think on your own - what does usability mean? - Identify users of canvas. - Identify 2 goals/tasks for Canvas - Use the usability terminology to analyse usability of Canvas for those tasks.