Human Computer Interface Design Pedro Mejia Alvarez CINVESTAV-IPN Based on the course on Software Engineering of Er-Yu Ding Software Institute, NJU

Main Contents 1.Why HCI Design? 2.Objectives of HCI Design 3.Basics of HCI Design 4.Golden Principles and Rules of HCI Design 5.Process of HCI Design

1.Why HCI Design? ——What is HCI? UI design is not just about the arrangement of media on a screen It’s designing an entire experience for people, hence a “look and feel” Psychology: building a mental model Ergonomics: facilitating navigation

1.Why HCI Design? System users often judge a system by its interface rather than its functionality. – User interfaces should be designed to match the skills, experience and expectations of its anticipated users. A poorly designed interface can cause a user to make catastrophic errors. – A poor UI is often a reason why so many software systems are never used. “A user interface is well-designed when the program behaves exactly how the user thought it would.” – Joel Spolsky

1.Why HCI Design? ——We remember only the bad! A good interface should be transparent Bad interfaces cause user frustration – “What was this product designer thinking?” GOODBAD

2. Objectives of HCI Design ——What is a good HCI interface design A good HCI interface design encourage an easy, natural, and engaging interaction between a user and a system. It allows users to carry our their required tasks. With a good user interface, users forget that they are using a computer. How to judge good or bad? Usability!

2. Objectives of HCI Design —— Usability attributes of an interface Usability is not a single, one-dimensional property of a user interface – Learnability: learn easily, user can do things with it in little time – Efficiency: skilled users can use it with great efficiency – Memorability: interrupted users can continual use it,do not need to starting from scratch – Errors: little errors, resume quickly from errors – Satisfaction: make users pleased

2. Objectives of HCI Design —— Learn Curve

2. Objectives of HCI Design —— Memory Involves encoding and recalling knowledge and acting appropriately We don’t remember everything – involves filtering and processing Context is important in affecting our memory We recognize things much better than being able to recall things – The rise of the GUI over command-based interfaces Better at remembering images than words – The use of icons rather than names

2. Objectives of HCI Design —— Human Factors in Interface Design Limited short-term memory – People can instantaneously remember about 7 items of information. If you present more than this, they are more liable to make mistakes. People make mistakes – When people make mistakes and systems go wrong, inappropriate alarms and messages can increase stress and hence the likelihood of more mistakes. People are different – People have a wide range of physical capabilities. Designers should not just design for their own capabilities. People have different interaction preferences – Some like pictures, some like text.

3. Basics of HCI Design ——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? User interaction and information presentation may be integrated through a coherent framework such as a user interface metaphor.

3. Basics of HCI Design —— Interaction styles Direct manipulation – Easiest to grasp with immediate feedback – Difficult to program Menu selection – User effort and errors minimized – Large numbers and combinations of choices a problem Form fill-in – Ease of use, simple data entry – Tedious, takes a lot of screen space Command language – Easy to program and process – Difficult to master for casual users Natural language – Great for casual users – Tedious for expert users

3. Basics of HCI Design —— An Example of Direct manipulation Control panel interface

3. Basics of HCI Design —— Direct manipulation Advantages: – Users feel in control of the computer and are not intimidated by it. – User learning time is relatively short. – User get immediate feedback on their actions. Mistakes can often be detected and corrected quickly. Problems: – How can an appropriate information model and metaphors be derived? – Given that users have a large information space, how can they navigate around that space and always aware of their current position? – Interfaces usually are complicated.

Pop-up menu Pull-down menu Walking menu 3. Basics of HCI Design —— Menu Systems pull-down menus: – predictable, but need more screen space – display the menu title. – User can select commands through this menu. pop-up menus: – flexible, tailorable, may cause user surprise – -They are associated with entities (such as a field). – Selecting the entity then clicking a mouse button --> cause the menu to appear.

3. Basics of HCI Design —— Menu Systems Advantages: – Users do not need to know the command names. – Typing efforts is minimal. – Some user errors can be avoid. – Context-dependent help can be provided. Problems: – Actions which involve logical conjunction (and) or disjunction (or) are awkward to represent – Take care the structure of large menus. Solutions: a) scrolling menus,b) hierarchical menusc) walking menus,d) associated control panels

3. Basics of HCI Design —— Form-based interface Advantage – For structured data representation and filling in Problems – Just for structured data representation and filling in

3. Basics of HCI Design ——Command-line interfaces Advantages: – Implementation is easy and simple due to the language processing. – It can support very complex systems with a lot of commands. – User interface needs a little effort. – Typing efforts is minimal. – Some user errors can be avoid. – Context-dependent help can be provided. Problems: – Users must learn and remember all commands. – Hard to learn the system and not easy for operations. – Users inevitably make errors.

3. Basics of HCI Design —— 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

3. Basics of HCI Design —— Multiple user interfaces

3. Basics of HCI Design —— Interface Types Batch: without interaction – Copy, -message, etc. Command: one-dimension interface – For skilled users with fixed tasks Full screen: two-dimension interface – form, menu, navigation key – For skilled users with limited number tasks Graphics screen: two and half dimension interface – Window, menu, icon, position devices (mouse, etc.) – Object-oriented, operate directly Next generation in the future: three or more dimensions interface – Additional dimensions: time, voice, etc. – More facilitative, more personalization

4. Golden Principles and Rules of HCI Design —— Golden Rules Place the user in control Reduce the user’s memory load Be consistent

4. Golden Principles and Rules of HCI Design —— Place the User in Control Define interaction modes in a way that does not force a user into unnecessary or undesired actions. Provide for flexible interaction. Allow user interaction to be interruptible and undoable. Streamline interaction as skill levels advance and allow the interaction to be customized. Hide technical internals from the casual user. Design for direct interaction with objects that appear on the screen.

4. Golden Principles and Rules of HCI Design —— Reduce the User ’ s Memory Load Reduce demand on short-term memory. Establish meaningful defaults. Define shortcuts that are intuitive. The visual layout of the interface should be based on a real world metaphor. Disclose information in a progressive fashion.

4. Golden Principles and Rules of HCI Design —— Make the Interface Consistent Allow the user to put the current task into a meaningful context. Maintain consistency across a family of applications. If past interactive models have created user expectations, do not make changes unless there is a compelling reason to do so.

4. Golden Principles and Rules of HCI Design —— Ten Principles （ 1 ） Compact and natural dialogue – Design graph and color – Few is much Using user language Least memory needed for user Consistent Feedback

4. Golden Principles and Rules of HCI Design —— Ten Principles （ 2 ） Identify exit clear Shortcut Good error message Avoid mistake Help and document

4. Golden Principles and Rules of HCI Design —— Which Rules are there? Obtrusive Assistance

If your program model is nontrivial, it’s probably wrong (“invisible sheets” in Excel) Click hereThis window comes to top! 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

Bad Wizards

XEROX’s GUI (1981) 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

How do the following screen objects afford? – What if you were a novice user? – Would you know what to do with them? 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

phones, remote controlscalculators, computer keypads 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

click 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

floating menu barhuge system tray How many users want these? 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

vs. (30% usability)(100% usability) 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

vs. 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

vs. (no dialog) Which is better for an intimidated user? 4. Golden Principles and Rules of HCI Design —— Which Rules are there?

5. Process of HCI Design ——Four basic activities There are four basic activities in interaction design: 1.Identifying needs and establishing requirements 2.Developing alternative designs 3.Building interactive versions of the designs 4.Evaluating designs

5. Process of HCI Design —— User Interface Design Process

5. Process of HCI Design —— Interface Analysis Interface analysis means understanding – User Individual characteristics User groups Frequency of usage – Work Task features Time constraints Errors – Content Figure, graph or text – Environment General environment factors Organization Culture

5. Process of HCI Design —— Interface Analysis: User Why do we need to understand users? – Interacting with technology is cognitive We need to take into account cognitive processes involved and cognitive limitations of users – We can provide knowledge about what users can and cannot be expected to do Identify and explain the nature and causes of problems users encounter – Supply theories, modeling tools, guidance and methods that can lead to the design of better interactive products

5. Process of HCI Design —— Interface Analysis: User Usage profiles – Novice or first-time users – Knowledgeable intermittent users – Expert frequent users User characteristics – Age – Gender – Physical abilities – Education – Cultural or ethnic background – Training – Motivation – Goals – Personality

5. Process of HCI Design —— Interface Analysis: User Are users trained professionals, technician, clerical, or manufacturing workers? What level of formal education does the average user have? Are the users capable of learning from written materials or have they expressed a desire for classroom training? Are users expert typists or keyboard phobic? What is the age range of the user community? Will the users be represented predominately by one gender? How are users compensated for the work they perform? Do users work normal office hours or do they work until the job is done? Is the software to be an integral part of the work users do or will it be used only occasionally? What is the primary spoken language among users? What are the consequences if a user makes a mistake using the system? Are users experts in the subject matter that is addressed by the system? Do users want to know about the technology the sits behind the interface?

5. Process of HCI Design —— Interface Analysis: Work What tasks will a user of the system perform? – High level - why people use the system – Low level - tasks involved in using the system Tasks define basic interaction style – HCI design should be transparent to user – Business(user model ).VS. Logic( designer model)

5. Process of HCI Design —— Interface Analysis: Work Task profiles – Decomposition into multiple middle-level task actions, which are refined into atomic actions – task frequencies of use – matrix of users and tasks helpful Interaction styles – Direct manipulation – Menu selection – Form fillin – Command language – Natural language

5. Process of HCI Design —— Interface Analysis: Work Task Analysis and Modeling – Use-cases define basic interaction – Task elaboration refines interactive tasks – Object elaboration identifies interface objects (classes) – Workflow analysis defines how a work process is completed when several people (and roles) are involved – Layered representation according to task refinements

5. Process of HCI Design —— Interface Analysis: Work Answers to the following questions … – What work will the user perform in specific circumstances? – What tasks and subtasks will be performed as the user does the work? – What specific problem domain objects will the user manipulate as work is performed? – What is the sequence of work tasks — the workflow? – What is the hierarchy of tasks?

5. Process of HCI Design —— Interface Analysis: Content Terminology Prompts Menus Help screens Color Layout Capitalization Fonts Most frequently violated

5. Process of HCI Design —— Interface Analysis: Content Are different types of data assigned to consistent geographic locations on the screen (e.g., photos always appear in the upper right hand corner)? Can the user customize the screen location for content? Is proper on-screen identification assigned to all content? If a large report is to be presented, how should it be partitioned for ease of understanding? Will mechanisms be available for moving directly to summary information for large collections of data. Will graphical output be scaled to fit within the bounds of the display device that is used? How will color to be used to enhance understanding? How will error messages and warning be presented to the user?

5. Process of HCI Design —— Interface Analysis: Content Shape

5. Process of HCI Design —— Interface Analysis: Content Dynamic information display

5. Process of HCI Design —— Interface Analysis: Content Color Use Guidelines – Limit the number of colors and be conservative in their use. No more than 4 or 5 colors in a window. – Use color change to show a change in system status. – Use color to support the task that users are trying to perform. Color should emphasize the most important data. – Use color coding in a thoughtful and consistent way. Using red to indicate success is probably not a good idea. – Be careful about color pairings. E.g. Dark blue on black is not a good choice. – Avoid associating meaning with colors. Users may not see colors or associate with different meaning.

5. Process of HCI Design —— Interface Analysis: Environments Systems model Physical environments Culture ambience

5. Process of HCI Design —— Interface Analysis: Environments System model – Global – Temporary – Background Physical environments – Color – Noice – Etc.

Cultural constraints – Learned arbitrary conventions 5. Process of HCI Design —— Interface Analysis: Environments

Cultural constraints – How/what to represent the target culture? – Should designs impose foreign values?

5. Process of HCI Design —— Interface Design Steps Using information developed during interface analysis, define interface objects and actions (operations). Define events (user actions) that will cause the state of the user interface to change. Model this behavior. Depict each interface state as it will actually look to the end-user. Indicate how the user interprets the state of the system from information provided through the interface.

5. Process of HCI Design ——Prototyping HCI Interfaces High-fidelity: implement it in Flash Low-fidelity: use paper, glue, index cards, tape, colored markers Advantages of low-fidelity prototype? – Easy and inexpensive to build – Easy and cheap to change, many times Disadvantages of low-fidelity prototype? – Don’t simulate computer response time accurately

5. Process of HCI Design ——Prototyping HCI Interfaces:An example

5. Process of HCI Design —— Interface Design Patterns Patterns are available for: – The complete UI – Page layout – Forms and input – Tables – Direct data manipulation – Navigation – Searching – Page elements (Wizard) – e-Commerce

5. Process of HCI Design ——HCI Design Issues Response time Help facilities Error handling Menu and command labeling Application accessibility Internationalization

5. Process of HCI Design ——HCI Design 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

5. Process of HCI Design —— Simple evaluation techniques Questionnaires for user feedback Video recording of system use and subsequent tape evaluation. Instrumentation of code to collect information about facility use and user errors. The provision of a grip button for on-line user feedback.

5. Process of HCI Design —— Design Evaluation Cycle

Conclusions