1. Lecture 6 User Interface Design
SFDV Principles of Information Systems
Lecture 6
User Interface Design

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

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

9. 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

10. 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]

11. 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]

12. 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

13. 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%)