Interactive Systems Design & Evaluation

1. Interactive Systems Design & Evaluation : John T Burns • e-mail jtb@dmu.ac.uk Mandatory Text User Interface design and Evaluation Debbie Stone et al Morgan Kaufman 2005 Recommended Text : Interaction Design Beyond HCI Preece Rodgers et al 2nd Ed 2007 User Centred Wed Design, McCracken & Wolfe Pearson Prentice Hall, 2004 Human Computer Interaction Smith – Atakan Pub Thomson 2006 ISDE J T Burns September2011

2. Objectives of this Lecture • To outline what we mean by ISDE • To define HCI • To demonstrate the need for ISDE • To indicate the scope of ISDE • To consider some general principles of HCI design ISDE J T Burns September2011

3. What is ISDE about? • Interactive systems are designed to enable communication between the system and the user • This takes place via the systems ‘user interface’ • ISDE is concerned with:- • Designing interactive systems to support human activities • Applying usability engineering techniques to evaluate the effectiveness and appropriateness of the design ISDE J T Burns September2011

4. Goals of interaction design • Develop usable products • Usability means easy to learn, effective to use and provide an enjoyable experience • Involve users in the design process ISDE J T Burns September2011

5. Some Interactive Devices ISDE J T Burns September2011

6. Some definitions – From HCI - ID • Human-Computer Interaction • a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of the major phenomena surrounding them • Interaction design • The design of spaces for human communication and interaction • User Interface • any boundary between the human user and the computer system (includes documentation and training material) • not restricted to screens, keyboards and mice ISDE J T Burns September2011

7. What is HCI • HCI is concerned about :- • Finding out how people use computers • Trying to ensure that systems are designed to closely match users’ needs • Ensuring that users can make sense of the information that is presented to them • Ensuring that the user can communicate/interact with the system • This is not always the case!! ISDE J T Burns September2011

8. Getting it wrong! • Some examples of bad design • The Dishwasher • The Vending Machine • The ATM ISDE J T Burns September2011

9. The dishwasher What is wrong with this display message? Error2 ISDE J T Burns September2011

10. Why is this vending machine so bad? • Need to push buttonfirst to activate reader • Normally insert bill first before making selection • Contravenes well known convention From: www.baddesigns.com ISDE J T Burns September2011

11. ATM ISDE J T Burns September2011

12. ISDE J T Burns September2011

13. Getting it right! • These illustrate 3 key factors that the designer needs to focus on • The user • The task • The environment • Next slide shows other factors ISDE J T Burns September2011

14. Organisational Factors Environmental Factors Health and Safety Factors Comfort Factors The User User Interface Task Factors Constraints System Functionality Productivity Factors ISDE J T Burns September2011

15. What is involved in the process of interaction design • Identify needs and establish requirements • Develop alternative designs • Build interactive prototypes that can be communicated and assessed • Evaluate what is being built throughout the process ISDE J T Burns September2011

16. Core characteristics of interaction design • users should be involved through the development of the project • specific usability and user experience goals need to be identified, clearly documented and agreed at the beginning of the project • iteration is needed through the core activities ISDE J T Burns September2011

17. Introduction to ISDE – Part 2 • Objectives • To outline general design principles • Justifying the need for good design • To identify features of good design • To consider design implications ISDE J T Burns September2011

18. Design principles • Wide range of design principles- guidelines or heuristics • Provide list of 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 • Design is complex not simply ticking checklist! • Great skill is required ISDE J T Burns September2011

19. Design Goals • Interactive designers aim to achieve the following • Safe secure design • Utility • Effectiveness • Efficiency • Usability • Appeal • They also apply & use general design principles ISDE J T Burns September2011

20. 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 ISDE J T Burns September2011

21. 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 ISDE J T Burns September2011

22. 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” ISDE J T Burns September2011

23. Constraints • Restricting the possible actions that can be performed • Helps prevent user from selecting incorrect options • Three main types (Norman, 1999) • physical • cultural • logical ISDE J T Burns September2011

24. 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? • Often used where safety is an issue – examples? ISDE J T Burns September2011

25. Logical constraints • Exploits people’s everyday common sense reasoning about the way the world works • An example is the logical relationship between physical layout of a device and the way it works as the next slide illustrates ISDE J T Burns September2011

26. 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 ISDE J T Burns September2011

27. 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 ISDE J T Burns September2011

28. Cultural constraints • Learned arbitrary conventions like red triangles for warning • Can be universal or culturally specific ISDE J T Burns September2011

29. Universal • Can you think of some icons for the following • Restaurants • Banks • Garage/Services ISDE J T Burns September2011

30. Mapping • Relationship between controls and their movements and the results in the world • Why is this a poor mapping of control buttons? ISDE J T Burns September2011

31. 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 ISDE J T Burns September2011

32. Activity on mappings • Which controls go with which rings (burners)? A B C D ISDE J T Burns September2011

33. Why is this a better design? ISDE J T Burns September2011

34. 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 ISDE J T Burns September2011

35. When consistency breaks down • What happens if there is more than one command starting with the same letter? • e.g. save, spelling, select, style • Have to find other initials or combinations of keys, thereby breaking the consistency rule • E.g. ctrl+S, ctrl+Sp, ctrl+shift+L • Increases learning burden on user, making them more prone to errors ISDE J T Burns September2011

36. Internal and external consistency • Internal consistency refers to designing operations to behave the same within an application • Difficult to achieve with complex interfaces • External consistency refers to designing operations, interfaces, etc., to be the same across applications and devices • Very rarely the case, based on different designer’s preference ISDE J T Burns September2011

37. Keypad numbers layout • A case of external inconsistency (a) phones, remote controls (b) calculators, computer keypads 8 9 1 2 7 3 4 5 6 4 5 6 8 9 1 2 7 3 0 0 ISDE J T Burns September2011

38. 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 popularized in interaction design to discuss how to design interface objects • E.g. scrollbars to afford moving up and down, icons to afford clicking on ISDE J T Burns September2011

39. 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 ISDE J T Burns September2011

40. Justifying HCI • Poor interface design can lead to • Increased errors • User frustration • Poor system performance • User rejection - particularly true for WWW ISDE J T Burns September2011

41. Justifying HCI • Good Interface design will provide • Fail-safe systems • Competitive advantages • Financial rewards • Increased efficiency • User satisfaction and enjoyment ISDE J T Burns September2011

42. What makes for a good interface? • A good interface will • Provide feedback • Provide easy reversal of actions (relieves anxiety) • Give users feeling that they are in control • Reduce reliance on STM ISDE J T Burns September2011

43. Think about a car... • how much knowledge about a car do you need to be able to drive it? • do the best designed cars give the driver the most information about the engine, suspension, etc? • good design of the interface to the car includes designing controls that are • obvious to use • behave in the way you expect • give fast feedback • are comfortable to use • hide unnecessary information from the user ISDE J T Burns September2011

44. Perspectives on design • users are often not interested in the program and use it only as a tool to achieve some task in their work • give me £20 from my current account (ATM) • draw me a section of the valve called P1023 in a place I can define (CAD system) • manufacturers are aware of the importance of usability... • ... but often do not know how to design for usability and how to test or evaluate it effectively ISDE J T Burns September2011

45. Continued perspectives... • think ‘design first, implementation second’ • design the interface first for usability, only compromise in the design for ease of implementation later if necessary • think how the system and interface should support what the user wants to do, rather than what the system is capable of doing ISDE J T Burns September2011

46. Misconceptions about user interface design • a usable system has lots of functions • ‘I know it’s a bit hard to use but it’s all described in the Help system’ • ‘I know it works - I’ve got the people in the office (or on the course) to use it’ • I tested it and everything worked so I know the interface is good ISDE J T Burns September2011

47. User Centred Design • all systems need not be designed to suit everyone... • .... but should be designed around the needs and capabilities of those people who will use them usability - concerned with making systems easy to learn, easy to use and efficient to use ISDE J T Burns September2011

48. Implications for the design process • there must be an early focus on users and tasks • there must be a clear understanding of what particular usability attributes are important • to ensure usability targets can be met, there must be testing of prototypes of the design from an early stage in the process • results from prototype testing need to be used to modify the design and this is then retested - i.e. there are iterations in the design - test cycle • software tools are needed to support this process - to enable designs to be built and modified with little programming overhead ISDE J T Burns September2011

49. Design Methods • There is no single ‘golden’ design method that can ensure successful interactive design • Requires designer to gain an understanding of the problem and apply appropriate techniques • Fundamental to achieving success is the need to shift continually between two types of design activity ISDE J T Burns September2011

50. Design Activities • Analysis • During analysis we test the design to ensure it is meeting our targets for usability and quality • Synthesis • Here we shape the design drawing on fresh ideas, previous experience and solutions to similar problems ISDE J T Burns September2011