Lecture 6 User Interface Design SFDV2002 - Principles of Information Systems Lecture 6 User Interface Design

Overview What is the field of HCI? The limitations and capabilities of “Human” and “Computer” that influence the designing of user interfaces Examples of Interactions between humans and computers User Interface Design Need to understanding users Guidelines for creating usable user interfaces Approaches for evaluating user interfaces

Human Computer Interaction Human (Users) Computer “… involves the design, implementation and evaluation of interactive systems in the context of the user’s task and work” Interaction

What is Human Computer Interaction (HCI)? “… involves the design, implementation and evaluation of interactive systems in the context of the user’s task and work” Who are the users (humans)? performing tasks or processes As far as HCI goes it is not necessarily a single user: individual user: not just a user with a desktop group of users working together sequence of users: performing parts of tasks or processes Computers? Computer/technology but can include non-computerized parts of a system. desktop computer and other technology (e.g. mobile devices, etc.) What is meant by interactions Communication between the a user and computer Direct: involves dialog with feedback and control throughout the performance of tasks Indirect: involves background or batch processing

HCI: Multi-Disciplinary Subject Psychology and cognitive science Business Graphic design Psychology and cognitive science: provides knowledge of the user’s perceptual, cognitive and problem-solving skills Ergonomics: for the user’s physical capabilities Sociology: contributes to an understand of the wider context of the user’s interactions Computer science and engineering: skills to build the necessary technology Business: able to market it, etc. Graphic design: to produce an effective interface presentation Technical writing: production the manuals Ergonomics Technical writing Sociology Others … Computer science and engineering

Human: Capacities and Limitations Human (Users) Perceptual system Senses: sight, hearing, touch, taste, and smell e.g. visual processing system Motor skills e.g. movement time, reaction time, and speed and accuracy Human memory e.g. short term memory

Computer: Capacities and Limitations Input devices e.g. keyboard, positioning and pointing devices, handwriting recognition, speech recognition, others … Output devices e.g. Computer screens, 3D displays – Virtual Reality, Printing, Virtual Reality, etc. Memory and Processing Computer

Interaction: Different Styles Form Fill-In Direct Manipulation Interaction Menu Selection Command Language Natural Language [Schneiderman, 2004]

1- Direct manipulation When designers create a visual representation of the world of actions Interaction with objects on the screen instead of typing” Keyboard and mouse replaced with cursor-motion devices to select from a visible set of objects and actions First application using this interaction style was VisiCalc (1978) Desktop metaphor – notepad, calendar, calculator, folders containing documents 2- Menu selection Selects from lists of items most appropriate for the task at hand Designer need to be careful that all functions are supported. 3- Form fillin (also fill in the blanks) When data entry is required, menu selection usually becomes cumbersome, and form fillin is appropriate. Users see a display of related fields and associated labels that let the user know the permissible values 4- Command language Good for frequent users as command languages provides a strong feeling of control and initiative Users learn the syntax and can often express complex possibilities rapidly without having to read distracting prompts Error rates are high, training is necessary, and retention may be poor. 5- Natural languages Computers responding to natural language sentences or phrases engages – still being developed

Direct Manipulation Form Fill-In Command language Menu Selection Advantages Disadvantages Visually presents task concept May be hard to program Allows easy learning May require graphics display and point devices Allows easy retention Allow errors to be avoided Encourages exploration Affords high subjective satisfactions Advantages Disadvantages Simplifies data entry Consumes screen space Requires modest training Gives convenient assistance Command language Advantages Disadvantages Is flexible Has poor error handling Appeals to the “power” users Requires substantial training and memorization Supports user initiative Allows convenient creation user-defined macros Menu Selection Advantages Disadvantages Shorten learning time Present danger of many menus - overwhelm the user Reduces keystrokes May slow frequent users Structures decision making - all choices are presented Consumes screen space Permits use of dialog-management tools Requires rapid display rates Allows easy support or errors handling Natural language Advantages Disadvantages Relives burden of learning syntax Relieves burden of learning syntax May require more keystrokes [Source: Schneiderman, 2004]

User Profiles: Human Diversity Physical abilities and physical workplaces Cognitive and perceptual abilities Personality differences Cultural and international diversity Users with disabilities Elderly users [Source: Schneiderman, 2004]

User Profiles: Diversity of Users Novice (first-time users) Knowledgeable Intermittent Users Expert frequent Users “power” user: seek to get their work done quickly. Demand for rapid response time. Like to create macro or other abbreviated form to reduce the number of steps. Shortcuts through menus and other accelerators are requirements Broad knowledge of interface concepts, but have difficultly retaining the structure of menus. Protect against user partially forgetting sequences of actions assumed to know little of the task Anxiety about using computers inhibit learning Including things like instructions, dialog boxes, and online help

References Shneuiderman and Plaisant, Designing the User Interface, 4th Edition, Addison Wesley, 2005 Dix, et al., Human-computer interaction, 2nd Edition, Prentice Hall, 1998 Satzinger, et al., Systems Analysis and Design in a changing world, Thomson, 2007 -------------------------------------------------------- NOTE: Time for Practical Test 1 (10%)