Usability goals

1. Usability goals • Effective to use (Man kan göra det man vill göra.) • Efficient to use (Bra invävnad av funktionaliteten i människans pågående aktivitet, dvs. minimalt merarbete.) • Safe to use • Have good utility (Man kan göra det man vill göra på det sätt man vill. • Easy to learn • Easy to remember how to use

2. User experience goals • Satisfying - rewarding • Fun - support creativity • Enjoyable - emotionally fulfilling • Entertaining …and more • Helpful • Motivating • Aesthetically pleasing • Motivating

3. Usability and user experience goals • How do usability goals differ from user experience goals? • Are there trade-offs between the two kinds of goals? • e.g. can a product be both fun and safe? • How easy is it to measure usability versus user experience goals?

4. Design principles • Generalizable abstractions for thinking about different aspects of design • The do’s and don’ts of interaction design • What to provide and what not to provide at the interface • Derived from a mix of theory-based knowledge, experience and common-sense

5. Visibility • This is a control panel for an elevator. • How does it work? • Push a button for the floor you want? • Nothing happens. Push any other button? Still nothing. What do you need to do? It is not visible as to what to do! From: www.baddesigns.com

6. Visibility …you need to insert your room card in the slot by the buttons to get the elevator to work! How would you make this action more visible? • make the card reader more obvious • provide an auditory message, that says what to do (which language?) • provide a big label next to the card reader that flashes when someone enters • make relevant parts visible • make what has to be done obvious

7. Feedback • Sending information back to the user about what has been done • Includes sound, highlighting, animation and combinations of these • e.g. when screen button clicked on provides sound or red highlight feedback: “ccclichhk”

8. Constraints • Restricting the possible actions that can be performed • Helps prevent user from selecting incorrect options • Three main types (Norman, 1999) • physical • cultural • logical

9. Physical constraints • Refer to the way physical objects restrict the movement of things • E.g. only one way you can insert a key into a lock • How many ways can you insert a CD or DVD disk into a computer? • How physically constraining is this action? • How does it differ from the insertion of a floppy disk into a computer?

10. Logical constraints • Exploits people’s everyday common sense reasoning about the way the world works • An example is they logical relationship between physical layout of a device and the way it works as the next slide illustrates

11. Logical or ambiguous design? • Where do you plug the mouse? • Where do you plug the keyboard? • top or bottom connector? • Do the color coded icons help? From: www.baddesigns.com

12. How to design them more logically (i) A provides direct adjacent mapping between icon and connector (ii) B provides color coding to associate the connectors with the labels From: www.baddesigns.com

13. Cultural constraints • Learned arbitrary conventions like red triangles for warning • Can be universal or culturally specific

14. Which are universal and which are culturally-specific?

15. Mapping • Relationship between controls and their movements and the results in the world • Why is this a poor mapping of control buttons?

16. Mapping • Why is this a better mapping? • The control buttons are mapped better onto the sequence of actions of fast rewind, rewind, play and fast forward

17. Consistency • Design interfaces to have similar operations and use similar elements for similar tasks • For example: • always use ctrl key plus first initial of the command for an operation – ctrl+C, ctrl+S, ctrl+O • Main benefit is consistent interfaces are easier to learn and use

18. Affordances: to give a clue • Refers to an attribute of an object that allows people to know how to use it • e.g. a mouse button invites pushing, a door handle affords pulling • Norman (1988) used the term to discuss the design of everyday objects • Since has been much popularised in interaction design to discuss how to design interface objects • e.g. scrollbars to afford moving up and down, icons to afford clicking on

19. What does ‘affordance’ have to offer interaction design? • Interfaces are virtual and do not have affordances like physical objects • Norman argues it does not make sense to talk about interfaces in terms of ‘real’ affordances • Instead interfaces are better conceptualised as ‘perceived’ affordances • Learned conventions of arbitrary mappings between action and effect at the interface • Some mappings are better than others

20. Activity • Physical affordances: How do the following physical objects afford? Are they obvious?

21. Activity • Virtual affordances How do the following screen objects afford? What if you were a novice user? Would you know what to do with them?

22. Usability principles • Similar to design principles, except more prescriptive • Used mainly as the basis for evaluating systems • Provide a framework for heuristic evaluation

23. Usability principles (Nielsen 2001) • Visibility of system status • Match between system and the real world • User control and freedom • Consistency and standards • Help users recognize, diagnose and recover from errors • Error prevention • Recognition rather than recall • Flexibility and efficiency of use • Aesthetic and minimalist design • Help and documentation

24. Understanding and conceptualizing interaction

25. Recap • HCI has moved beyond designing interfaces for desktop machines • About extending and supporting all manner of human activities in all manner of places • Facilitating user experiences through designing interactions • Make work effective, efficient and safer • Improve and enhance learning and training • Provide enjoyable and exciting entertainment • Enhance communication and understanding • Support new forms of creativity and expression

26. Understanding the problem space • What do you want to create? • What are your assumptions? • Will it achieve what you hope it will?

27. A framework for analysing the problem space • Are there problems with an existing product? • Why do you think there are problems? • Why do you think your proposed ideas might be useful? • How would you see people using it with their current way of doing things? • How will it support people in their activities? • Will it really help them?

28. An example • What were the assumptions made by cell phone companies when developing WAP services? • Was it a solution looking for a problem?

29. Assumptions: realistic or wish-list? • People want to be kept informed of up-to-date news wherever they are - reasonable • People want to interact with information on the move - reasonable • People are happy using a very small display and using an extremely restricted interface - not reasonable • People will be happy doing things on a cell phone that they normally do on their PCs (e.g. surf the web, read email, shop, bet, play video games) - reasonable only for a very select bunch of users

30. From problem space to design space • Having a good understanding of the problem space can help inform the design space • e.g. what kind of interface, behavior, functionality to provide • But before deciding upon these it is important to develop a conceptual model

31. Conceptual model • Need to first think about how the system will appear to users (i.e. how they will understand it) • A conceptual model is a high level description of: • “the proposed system in terms of a set of integrated ideas and concepts about what it should do, behave and look like, that will be understandable by the users in the manner intended”

32. First steps in formulating a conceptual model • What will the users be doing when carrying out their tasks? • How will the system support these? • What kind of interface metaphor, if any, will be appropriate? • What kinds of interaction modes and styles to use? Always keep in mind when making design decisions how the user will understand the underlying conceptual model

33. Conceptual models • Many kinds and ways of classifying them • Here we describe them in terms of core activities and objects • Also in terms of interface metaphors

34. Conceptual models based on activities • Giving instructions • issuing commands using keyboard and function keys and selecting options via menus • Conversing • interacting with the system as if having a conversation • Manipulating and navigating • acting on objects and interacting with virtual objects • Exploring and browsing • finding out and learning things

35. 1. Giving instructions • Where users instruct the system and tell it what to do • e.g. tell the time, print a file, save a file • Very common conceptual model, underlying a diversity of devices and systems • e.g. CAD, word processors, VCRs, vending machines • Main benefit is that instructing supports quick and efficient interaction • good for repetitive kinds of actions performed on multiple objects

36. 2. Conversing • Underlying model of having a conversation with another human • Range from simple voice recognition menu-driven systems to more complex ‘natural language’ dialogues • Examples include timetables, search engines, advice-giving systems, help systems • Recently, much interest in having virtual agents at the interface, who converse with you, e.g. Microsoft’s Bob and Clippy

37. Pros and cons of conversational model • Allows users, especially novices and technophobes, to interact with the system in a way that is familiar • makes them feel comfortable, at ease and less scared • Misunderstandings can arise when the system does not know how to parse what the user says • e.g. child types into a search engine, that uses natural language the question: “How many legs does a centipede have?” and the system responds:

39. 3. Manipulating and navigating • Involves dragging, selecting, opening, closing and zooming actions on virtual objects • Exploit’s users’ knowledge of how they move and manipulate in the physical world • Exemplified by (i) what you see is what you get (WYSIWYG) and (ii) the direct manipulation approach (DM) • Shneiderman (1983) coined the term DM, came from his fascination with computer games at the time

40. Core principles of DM • Continuous representation of objects and actions of interest • Physical actions and button pressing instead of issuing commands with complex syntax • Rapid reversible actions with immediate feedback on object of interest

41. Why are DM interfaces so enjoyable? • Novices can learn the basic functionality quickly • Experienced users can work extremely rapidly to carry out a wide range of tasks, even defining new functions • Intermittent users can retain operational concepts over time • Error messages rarely needed • Users can immediately see if their actions are furthering their goals and if not do something else • Users experience less anxiety • Users gain confidence and mastery and feel in control

42. What are the disadvantages with DM? • Some people take the metaphor of direct manipulation too literally • Not all tasks can be described by objects and not all actions can be done directly • Some tasks are better achieved through delegating • e.g. spell checking • Can become screen space ‘gobblers’ • Moving a mouse around the screen can be slower than pressing function keys to do same actions

43. 4. Exploring and browsing • Similar to how people browse information with existing media (e.g. newspapers, magazines, libraries, pamphlets) • Information is structured to allow flexibility in way user is able to search for information • e.g. multimedia, web

44. Conceptual models based on objects • Usually based on an analogy with something in the physical world • Examples include books, tools, vehicles • Classic: Star Interfacebased on officeobjects Johnson et al (1989)

45. Another classic: the spreadsheet (Bricklin) • Analogous to ledger sheet • Interactive and computational • Easy to understand • Greatly extending what accountants and others could do www.bricklin.com/history/refcards.htm

46. Which conceptual model is best? • Direct manipulation is good for ‘doing’ types of tasks, e.g. designing, drawing, flying, driving, sizing windows • Issuing instructions is good for repetitive tasks, e.g. spell-checking, file management • Having a conversation is good for children, computer-phobic, disabled users and specialised applications (e.g. phone services) • Hybrid conceptual models are often employed, where different ways of carrying out the same actions is supported at the interface - but can take longer to learn

47. Interface metaphors • Interface designed to be similar to a physical entity but also has own properties • e.g. desktop metaphor, web portals • Can be based on activity, object or a combination of both • Exploit user’s familiar knowledge, helping them to understand ‘the unfamiliar’ • Conjures up the essence of the unfamiliar activity, enabling users to leverage of this to understand more aspects of the unfamiliar functionality

48. Benefits of interface metaphors • Makes learning new systems easier • Helps users understand the underlying conceptual model • Can be very innovative and enable the realm of computers and their applications to be made more accessible to a greater diversity of users

49. Problems with interface metaphors • Break conventional and cultural rules • e.g. recycle bin placed on desktop • Can constrain designers in the way they conceptualize a problem space • Conflict with design principles • Forces users to only understand the system in terms of the metaphor • Designers can inadvertently use bad existing designs and transfer the bad parts over • Limits designers’ imagination in coming up with new conceptual models

50. Conceptual models: from interaction mode to style • Interaction mode: • what the user is doing when interacting with a system, e.g. instructing, talking, browsing or other • Interaction style: • the kind of interface used to support the mode, e.g. speech, menu-based, gesture