1. User Interface Design Yonsei University 2 nd Semester, 2013 Sanghyun Park

2. Topics Covered  Design Issues  UI Design Process  Interface Evaluation

3. User Interface  User interfaces should be designed to match the skills, experience and expectations of its anticipated users  System users often judge a system by its interface rather than its functionality  A poorly designed interface can cause a user to make catastrophic errors  Poor user interface design is the reason why so many software systems are never used

4. Human Factors In Interface Design  Limited short-term memory  People make mistakes  People are different  People have different interaction preferences

5. User Interface Design Principles

6. Design Issues In User Interfaces  The designer of a user interface to a computer is faced with two key questions:  How should the user interact with the computer system?  How should information from the computer system be presented to the user?  A coherent user interface must integrate user interaction with information presentation

7. User Interaction Styles (1/2)  Direct manipulation  Menu selection  Form fill-in  Command language  Natural language

8. User Interaction Styles (2/2)

9. Multiple User Interfaces

10. Information Presentation  Information presentation is concerned with presenting system information to system users  The information may be presented directly (e.g. text in a word processor) or may be transformed in some way for presentation (e.g. in some graphical form)

11. Information Presentation Factors  Is the information textual or numeric?  Is the user interested in precise information or the relationships between different data values?  How quickly do information values change? Must the change be indicated immediately?  Must the user take some action in response to a change?

12. Data Visualization  Concerned with techniques for displaying large amounts of information  Visualization can reveal relationships between entities and trends in the data  Examples of data visualizations are:  Weather information collected from a number of sources is shown as a weather map  The state of a telephone network is displayed as a linked set of nodes in a network management center  A model of a molecule is displayed in 3 dimensions  A set of web pages is displayed as a hyperbolic tree

13. Color In Interface Design  Color can improve UI by helping users understand and manage complexity  However, it is easy to misuse color and to create UIs that are unattractive and error-prone  Common mistakes in the use of color in interface design include:  The use of color to communicate meaning  The over-use of color in the display

14. Color Use Guidelines  Limit the number of colors  Use color change to show a change in a system status  Use color coding to support the task users are trying to perform  Use color coding in a thoughtful and consistent way  Be careful about color pairings

15. Error Messages  The background and experience of users should be the determining factor in message design  Messages should be polite, concise, consistent, and constructive  Messages should suggest how the error might be corrected  Error message should be linked to a context-sensitive on- line help system

16. Design Factors In Message Wording

17. User Interface Design Process

18. Interface Evaluation  Interface evaluation is the process of assessing the usability of an interface and checking that it meets user requirements  Full scale evaluation is very expensive and impractical for most systems  Ideally, an interface should be evaluated against a usability specification based on usability attributes. However, it is rare for such specification to be produced

19. Usability Attributes

20. Simple Evaluation Techniques  Questionnaires for user feedback  Observation of users at work with the system  Video snapshots of typical system use  The inclusion in the software of code to collect information about the most-used facilities and the most common errors