User Interface Design - Effective Software Systems PDF

User interface design https://youtu.be/NTmh8l-Xl4c?si=rOofaZTkVnj4WQo2 1 Objectives  To suggest some general design principles for user interface design  To explain different interaction styl...

User interface design https://youtu.be/NTmh8l-Xl4c?si=rOofaZTkVnj4WQo2 1 Objectives  To suggest some general design principles for user interface design  To explain different interaction styles  To introduce styles of information presentation  To describe the user support which should be built-in to user interfaces  To introduce usability attributes and system approaches to system evaluation 2  Topics covered  User interface design principles  User interaction  Information presentation  User support  Interface evaluation 3 The user interface  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  Graphical user interfaces  Most users of business systems interact with these systems through graphical interfaces although, in some cases, legacy text-based interfaces are still used 5 GUI characteristics Characteristic Description Windows Multiple windows allow different information to be displayed simultaneously on the user’s screen. Icons Icons different types of information. On some systems , icons represent files; on others, icons represent processes. Menus Commands are selected from a menu rather than typed in a command language. Pointing A pointing device such as a mous e is used for selecting choices from a menu or indicating items of interes t in a window. Graphics Graphical elements can be mixed with text on the same display. 6  GUI advantages  They are easy to learn and use.  Users without experience can learn to use the system quickly.  The user may switch quickly from one task to another and can interact with several different applications.  Information remains visible in its own window when attention is switched.  Fast, full-screen interaction is possible with immediate access to anywhere on the screen 7 User-centred design  User-centred design is an approach to UI design where the needs of the user are paramount and where the user is involved in the design process  UI design always involves the development of prototype interfaces 8  Analyse and Produce paper- Evaluate design understand user based design with end-users activities prototype Produce Design Evaluate design dynamic design prototype with end-users prototype Executable Implement prototype final user interface User interface design process 9 UI design principles  UI design must take account of the needs, experience and capabilities of the system users  Designers should be aware of people’s physical and mental limitations (e.g. limited short- term memory) and should recognise that people make mistakes  UI design principles underlie interface designs although not all principles are applicable to all designs 10  User interface design principles Principle Description User familiarity The interface should use terms and concepts which are drawn from the experience of the people who will make most use of the system. Consistency The interface should be consistent in that, wherever possible, comparable operations should be activated in the same way. Minimal surprise Users should never be surprised by the behaviour of a system. Recoverability The interface should include mechanisms to allow users to recover from errors. User guidance The interface should provide meaningful feedback when errors occur and provide context-sensitive user help facilities. User diversity The interface should provide appropriate interaction facilities for different types of system user. 11 Design principles User familiarity Consistency Minimal surprise The interface should be The system should display an If a command operates in a based on user-oriented terms appropriate level of known way, the user should and concepts rather than consistency. Commands and be computer concepts. For menus should have the same able to predict the operation example, an office system format, Command of comparable commands should use concepts such as punctuation should be letters, documents, folders similar, etc. etc. rather than directories, file identifiers, etc. 12  Design principles  Recoverability  The system should provide some resilience to user errors and allow the user to recover from errors. This might include an undo facility, confirmation of destructive actions, 'soft' deletes, etc.  User guidance  Some user guidance such as help systems, on-line manuals, etc. should be supplied  User diversity  Interaction facilities for different types of user should be supported. For example, some users have seeing difficulties and so larger text should be available 13 User-system interaction Two problems must be addressed in interactive systems design  How should information from the user be provided to the computer system?  How should information from the computer system be presented to the user? 14  Interaction styles  Direct manipulation  Menu selection  Form fill-in  Command language  Natural language 15 Interaction Main advantages Main disadvantages Application style examples Direct Fast and intuitive May be hard to implement Video games manipulation interaction Only suitable where there CAD systems Easy to learn is a visual metaphor for tasks and objects Menu selection Avoids user error Slow for experienced users Most general-purpose Little typing required Can become complex if systems many menu options Form fill-in Simple data entry Takes up a lot of screen Stock control, Personal Easy to learn space loan processing Command Powerful and flexible Hard to learn Operating systems, language Poor error management Library information retrieval systems Natural Accessible to casual Requires more typing Timetable systems language users Natural language WWW information Easily extended understanding systems are retrieval systems unreliable Advantages and disadvantages 16  Direct manipulation advantages  Users feel in control of the computer and are less likely to be intimidated by it  User learning time is relatively short  Users get immediate feedback on their actions so mistakes can be quickly detected and corrected 17 Direct manipulation problems  The derivation of an appropriate information space model can be very difficult  Given that users have a large information space, what facilities for navigating around that space should be provided?  Direct manipulation interfaces can be complex to program and make heavy demands on the computer system 18 19 Control panel interface LabVIEW TM Control Panel interface for automatic liquid handling. Rossi, Michele & Thei, Federico & Tartagni, Marco. (2011). An Automatic System for Bilayer Lipid Membrane Formation and Monitoring. 20  Menu systems Users make a selection from a list of possibilities presented to them by the system The selection may be made by pointing and clicking with a mouse, using cursor keys or by typing the name of the selection May make use of simple-to-use terminals such as touchscreens 21 Advantages of menu systems Users need not remember command names as they are always presented with a list of valid commands Typing effort is minimal User errors are trapped by the interface Context-dependent help can be provided. The user’s context is indicated by the current menu selection 22   Actions which involve logical conjunction (and) or disjunction (or) are awkward to represent  Menu systems are best suited to presenting aProblems small number of choices. If there are many with menu choices, some menu structuring facility mustsystems be used  Experienced users find menus slower than command language 23 Form-based interface NE W BOOK Title ISBN Author Price Publication Publisher date Number of Edition copies Classification Loan status Date of Order purchase status 24  Command interfaces  User types commands to give instructions to the system e.g. UNIX  May be implemented using cheap terminals.  Easy to process using compiler techniques  Commands of arbitrary complexity can be created by command combination  Concise interfaces requiring minimal typing can be created 25 Problems with command interfaces Users have to learn and remember a command language. Command interfaces are therefore unsuitable for occasional users Users make errors in command. An error detection and recovery system is required System interaction is through a keyboard so typing ability is required 26   Often preferred by experienced users because they allow for faster interaction with the system  Not suitable for casual or inexperienced users Command  May be provided as an languages alternative to menu commands (keyboard shortcuts). In some cases, a command language interface and a menu-based interface are supported at the same time 27 Natural language interfaces The user types a command in a natural language. Generally, the vocabulary is limited and these systems are confined to specific application domains (e.g. timetable enquiries) NL processing technology is now good enough to make these interfaces effective for casual users but experienced users find that they require too much typing 28  Multiple user interfaces Command Gr aphical user language interface interface Command GUI language manager interpreter Operating system 29 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) The Model-View-Controller approach is a way of supporting multiple presentations of data 30  Information presentation Information to Presentation be displayed software Display 31 Information presentation Static information Dynamic information Initialised at the beginning of a session. It Changes during a session and the changes does not change during the session must be communicated to the system user May be either numeric or textual May be either numeric or textual 32  Information display factors Is the user interested in precise information or data relationships? How quickly do information values change? Must the change be indicated immediately? Must the user take some action in response to a change? Is there a direct manipulation interface? Is the information textual or numeric? Are relative values important? 33 Alternative information presentations Jan Feb Mar April May June 2842 2851 3164 2789 1273 2835 4000 3000 2000 1000 0 Jan Feb Mar April May June 34  Analogue vs. digital presentation Digital Compact - takes up little screen space presentation Precise values can be communicated Easier to get an 'at a glance' impression of a value Analogue Possible to show relative values presentation Easier to see exceptional data values 35 Dynamic information display 1 0 10 20 4 2 3 Dial with needle Pie chart Thermometer Horizontal bar 36  Displaying relative values Pressure Temper atu re 0 100 200 300 400 0 25 50 75 100 37 Textual highlighting ! The filename you have chosen h as been used. Please choose an other name Ch. 16 User interface design OK Cancel 38  Data visualisation  Concerned with techniques for displaying large amounts of information  Visualisation can reveal relationships between entities and trends in the data  Possible data visualisations are:  Weather information collected from a number of sources  The state of a telephone network as a linked set of nodes  Chemical plant visualised by showing pressures and temperatures in a linked set of tanks and pipes  A model of a molecule displayed in 3 dimensions  Web pages displayed as a hyperbolic tree 39 Colour displays  Colour adds an extra dimension to an interface and can help the user understand complex information structures  Can be used to highlight exceptional events  Common mistakes in the use of colour in interface design include:  The use of colour to communicate meaning  Over-use of colour in the display 40  Colour use guidelines  Don't use too many colours  Use colour coding to support use tasks  Allow users to control colour coding  Design for monochrome then add colour  Use colour coding consistently  Avoid colour pairings which clash  Use colour change to show status change  Be aware that colour displays are usually lower resolution 41 User support User guidance covers all system facilities to support users including on-line help, error messages, manuals etc. The user guidance system should be integrated with the user interface to help users when they need information about the system or when they make some kind of error The help and message system should, if possible, be integrated 42  Help and message system Application Help Error message interface system Message presentation system Help Error message frames texts 43 Error messages  Error message design is critically important. Poor error messages can mean that a user rejects rather than accepts a system  Messages should be polite, concise, consistent and constructive  The background and experience of users should be the determining factor in message design 44  Design factors in message wording Context The user guidance system should be aware of what the user is doing and should adjust the output message to the current context. Experience As users become famili ar with a system they become irritated by long, ‘meaningful’ messages. However, beginners find it difficult to understand s hort ters e statements of the problem. The user guidance system should provide both types of message and allow the us er to control message conciseness. Skill level Messages should be tailored to the user’s skills as well as their experience. Messages for the different classes of user may be expressed in different ways depending onthe terminology which is famili ar to the reader. Style Messages should be positive rather than negative. They should use the active rather than the passive mode of address. They should never be insulting or try to be funny. Culture Wherever possi ble, the designer of messages should be familiar with the culture of the country where the system is sold. There are distinct cultural differences between Europe, Asia and America. A suitable message for one culture might be unacceptable in another. 45 Nurse input of a patient’s name Please type thepatient nameinthe bo x thenc lic k onOK Bates ,J. OK Cancel 46  System and user-oriented error messages User-oriented err or message System-o riented error message Error #27 ? Patient J. Bates is not registered Invalid patient id entered Clic konP atientsf ora listofregistered patients Click on Retry to re-input a patient name Click on Help for more information OK Cancel Patients Help Retry Cancel 47 Help system design  Help? means ‘help I want information”  Help! means “HELP. I'm in trouble”  Both of these requirements have to be taken into account in help system design  Different facilities in the help system may be required 48  Help information Should not simply be an on-line manual Screens or windows don't map well onto paper pages. The dynamic characteristics of the display can improve information presentation. People are not so good at reading screen as they are text. 49 Help system use Multiple entry points should be provided so that the user can get into the help system from different places. Some indication of where the user is positioned in the help system is valuable. Facilities should be provided to allow the user to navigate and traverse the help system. 50  User documentation As well as on-line information, paper documentation should be supplied with a system Documentation should be designed for a range of users from inexperienced to experienced As well as manuals, other easy-to-use documentation such as a quick reference card may be provided 51 User document types System System Novice Experienced System evaluators administrators users users administrators Functional Installation Introductory Reference Administrator’s description document manual manual guide Description of How to install Getting Facility Operation and services the system started description maintenance 52  Brief description of what Functional description the system can do Presents an informal Introductory manual introduction to the system Document System reference Describes all system manual facilities in detail types System installation Describes how to install manual the system System Describes how to manage administrator’s the system when it is in use manual 53 User interface evaluation Some evaluation of a user interface design should be carried out to assess its suitability Full scale evaluation is very expensive and impractical for most systems Ideally, an interface should be evaluated against a usability specification. However, it is rare for such specifications to be produced 54  Usability attributes Attribute Description Learnability How long does it take a new user to become productive with the sys tem? Speed of operation How well does the system response match the user’s work practice? Robustness How tolerant is the system of user error? Recoverability How good is the system at recovering from user errors? Adaptability How closely is the system tied to a single model of work? 55  Questionnaires for user feedback  Video recording of system use and subsequent Simple tape evaluation. evaluation  Instrumentation of code to collect information techniques about facility use and user errors.  The provision of a grip button for on-line user feedback. 56   Interface design should be user-centred. An interface should be logical and consistent and help users recover from errors  Interaction styles include direct manipulation, menu systems form fill-in, Key points command languages and natural language  Graphical displays should be used to present trends and approximate values. Digital displays when precision is required  Colour should be used sparingly and consistently 57  Systems should provide on- line help. This should include “help, I’m in trouble” and “help, I want information”  Error messages should be positive rather than Key points negative.  A range of different types of user documents should be provided  Ideally, a user interface should be evaluated against a usability specification 58