Human Computer Interaction User Interface

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Human Computer InteractionUser Interface
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What is a User Interface?

• The user interface is the part of a software
  program that allow users to interact with
  computer (system) and carry out their task.

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User Interface

• Today, building the Human-Computer Interface
  consumes 50 70 percent of the systems
  development effort.
• In other words, to users, the interface is the
  system.
• Users care about what they enter into and get out
  of the system and how the entire experience of
  interaction feels.

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Human Computer Interaction User Interface
development cycle

• HCI design, prototyping, evaluation, and
  implementation of user interfaces (UIs)

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Iteration

• At every stage!

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Why Study User Interfaces?

• Major part of work for real programs
• approximately 50
• You will work on real software
• intended for users other than yourself
• Bad user interfaces cost expensive
• User interfaces are hard to get right
• people are different and unpredictable

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Who builds UIs?

• A team of specialists (ideally)
• graphic designers
• interaction / interface designers
• marketers
• test engineers
• software engineers

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Five Key Ideas about UIs in HCI

• Visibility
• Feedback
• Goal
• Affordance
• Task

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Five Key Ideas about UIs in HCI Cont.

• Visibility all necessary controls should be
  visible for the user he/she is supposed to be
  able to use them in correct way.
• Always keep users informed about what is going
  on, through providing appropriate feedback within
  reasonable time.
• Visibility is the mapping between a control and
  its effect
• Show controls (toolbars, menus).
• Indicate mappings (Toolbar icons and graphics,
  enable disable).
• Provide feedback (Messages).
• The User Interface should help the user always
  understand
• The current state of the system.
• What operations can be done.

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Five Key Ideas about UIs in HCI Cont.

• Feedback
• When anything changes it should be made visible.
• Feedback concerning the actions executed
• When you are executing an action give a feedback
  to the user.
• Feedback concerning their results
• After an action executed, display results and
  make user aware of the results.
• Goal
• A state the user wants to reach
• To be talking with somebody on the phone.
• To have saved a file.

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Five Key Ideas about UIs in HCI Cont.

• Affordance
• An affordance is a quality of an object, or an
  environment, which allows an individual to
  perform an action
• The set of operations and procedures that can be
  done to an object (is the fundamental properties
  of an object which express how it might be used).
• Perceived affordance is what typical users
  think can be done to an object
• Should a door be pulled or pushed?
• What does this icon mean?

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Affordance

• Every action should be mapped to a graphical icon
  which can easily be understood by users.
• After an action is accomplished, a sound should
  indicate whether the action is successful.
• Communicate with the user when necessary.

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Five Key Ideas about UIs in HCI Cont.

• Task
• An action the user wants to do
• To call somebody
• To save the file
• Goals ? tasks, tasks ? goals.

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Bad User Interfaces

• Hard to tell the difference between the two icons
  and names

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Interface design

• Interface design is important for several
  reasons
• The better the user interface the easier it is to
  train people to use it.
• Reducing training costs.
• The better your user interface the less help
  people will need to use it, so reducing your
  support costs.
• The better your user interface the more your
  users will like to use it.
• Increasing their satisfaction with the work that
  you have done.

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User Interface Malfunctions(??????? )

• Key idea
• There are no good user interfaces ... just user
  interfaces that fit(????? )
• A truly bad user interface never fits
• To maximize fitness, we must minimize the
  occurrence of malfunctions in the context of
  the expected use of the system.

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Definitions of malfunction

• A mismatch between what the user wants, needs or
  expects and what the system provides.
• A breakdown(???? ) in usability.
• An obstacle(???? ) to performing a desired
  task.

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The fit of HCI elements

• HCI should be designed to achieve a fit between
  the ( human ) user, computer and task.
• Fit The match between the computer design, the
  user and the task so as to optimize the human
  resources needed to accomplish the task.
• Performance Reflects both the efficiency of
  performing the task and the quality of the task
  product.
• Well-being reflects an overall concern with the
  users physical and psychological(???? )
  welfare(??? ).

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The fit of HCI elements leads to performance and
well-being
Human
Fit
Performance Well-being
Task
Computer
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What constitutes(???? ) a good user interface?

• Achieve required performance by operator(???? ),
  control and maintenance personnel.
• Minimize skill and personnel requirements and
  training time.
• Achieve required reliability of person-computer
  combinations ( reliability, availability,
  security and data integrity ).
• Foster(????? ) design standardization within and
  among systems ( integration, consistency and
  portability ).

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Human Computer InteractionUsability and Design
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Usability

• A usable system is
• easy to learn
• easy to remember how to use
• effective to use
• efficient to use
• safe to use
• enjoyable to use

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Why is usability important?

• Many everyday systems and products seem to be
  designed with little regard to usability.
• This list contains examples of interactive
  products
• mobile phone, computer, personal organizer,
  remote control, coffee machine, ATM, etc.

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List of common measurable goals for usability

• Time to learn how to operate the system.
• Speed of performance.
• Rate of errors made by users.
• Users retention(?????? ) time of information
  presented.
• Users satisfaction with the system.
• Yet high-quality HCI is not just about usability
  or performance. It is also about emotions and
  about the overall physical and social experience
  of interacting with computers.

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Principles supporting usability

• Learnability
• The ease with which new users can begin effective
  interaction and achieve maximal performance.
• Flexibility
• The multiplicity of ways the user and system
  exchange information.
• Robustness ( Powerful )
• The level of support provided to the user in
  determining successful achievement ( Error
  Handling ).

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1. Learnability Principles

• The ease with which new users can begin effective
  interaction and achieve maximal performance.
  There are a lot of aspects which support the
  learnability principle in usability subject, such
  as
• Predictability.
• Synthesizability.
• Generalizability.
• Familiarity.
• Consistency.

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learnability Principles Cont.

• Predictability
• Determining effect of future actions based on
  past interaction history.
• Synthesizability(????? )
• Assessing the effect of past actions.
• While the user learns the system, the user
  constructs a picture of the inner of the black
  box.

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learnability Principles Cont.

• Generalizability
• Extending specific interaction knowledge to new
  situations.
• The user guess the functionality of new commands.
• Can knowledge of one system/UI be extended to
  other similar ones?
• Example cut paste in different applications.

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learnability Principles Cont.

• Familiarity
• How prior knowledge applies to new system.
• New user get good clues to use the system.
• Names and icons that are common to the users
  domain.
• Consistency
• Likeness(????? ) in input/output behaviour
  arising from similar situations or task
  objectives.
• Operation perform similarly for similar inputs.

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2. Flexibility Principles

• Multiplicity of ways that users and system
  exchange information, and the following are some
  aspects which support the flexibility principle
• Dialog Initiative(?????? ).
• Multithreading.
• Task migratability(?????? ).
• Substitutivity(??????? ).
• Customizability.

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Flexibility Principles Cnt.

• Dialogue initiative
• Freedom from system imposed(???? ) constraints on
  input dialogue.
• Old dialogue boxes are called system pre-emptive.
  System does all prompts, user responds sometimes
  necessary.
• Modern dialogue boxes are called user
  pre-emptive. More flexible, user initiates
  actions.
• Multithreading
• Ability of system to support user interaction for
  more than one task at a time.
• Allow user to perform simultaneous tasks.

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Flexibility Principles Cnt.

• Task migratability
• Passing responsibility for task execution between
  user and system.
• The user perform the task or have the computer
  perform the tasks.
• Example Spell-checking.

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Flexibility Principles Cnt.

• Substitutivity
• Allowing equivalent values of input and output to
  be substituted for each other.
• Assume different forms for equivalent values.
• Allow different ways of presenting output.
• The user should be able to see the results in the
  units of the user's choice.

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Flexibility Principles Cnt.
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Flexibility Principles Cnt.

• Customizability
• Modifiability of the user interface by user or
  system ( adaptability ).
• The user modify the interface in order to improve
  efficiency.
• The user can add commands, or change font size
  for better visibility.

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3. Robustness(????? ) Principles

• Supporting user in determining successful
  achievement and assessment of goals, by the
  following concepts
• Observability.
• Recoverability.
• Responsiveness.
• Task Conformance.

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Principles robustness Cnt.

• Observability
• Ability of user to evaluate the internal state of
  the system from its perceivable representation.
• Browsability
• Explore current state (without changing it).
• Reachability
• Navigate through observable states.
• Persistence
• Is how long the system states or user inputs are
  visible to the user.

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Principles robustness Cnt.

• Recoverability
• Ability of user to take corrective action once an
  error has been recognized.
• At a minimum the user ought(??? ) to be able to
  correct the output, forward recovery, (Ability to
  fix when we cant undo).
•  
• Users have grown accustomed to the undo command,
  backward recovery.

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Principles robustness Cnt.

• Responsiveness
• How the user perceives the rate of communication
  with the system.
• Response time
• Time for system to respond in some way to user
  action (s).
• The system respond in suitable time.
• Some applications require msec response, others
  seconds and some applications can run overnight.
  

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Principles robustness Cnt.

• Task conformance
• Degree to which system services support (perform)
  all of the user's tasks.
• Task completeness
• Can system do all tasks?
• Does it allow user to define new tasks?

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User-centred design

• In UI design 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.

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The UI design process

• UI design is an iterative process involving close
  liaisons(???????? ????????? ) between users and
  designers.
• The 3 core activities in this process are
• User analysis. Understand what the users will do
  with the system
• System prototyping. Develop a series of
  prototypes for experiment
• Interface evaluation. Experiment with these
  prototypes with users.

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The design process
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User analysis

• User analyses have to be described in terms that
  users and other designers can understand.
• Scenarios where you describe typical
  episodes(??????? ) of use, are one way of
  describing these analyses.

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Analysis techniques

• Task analysis
• Models the steps involved in completing a task.
• Interviewing and questionnaires
• Asks the users about the work they do.
• Ethnography
• Observes the user at work.

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User interface prototyping

• The aim of prototyping is to allow users to gain
  direct experience with the interface.
• Prototyping may be a two-stage process
• Early in the process, paper prototypes may be
  used
• The design is then refined and increasingly
  sophisticated automated prototypes are then
  developed.

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User interface evaluation

• Some evaluation of a user interface design
  should be carried out to assess its suitability.
• Ideally, an interface should be evaluated against
  a usability specification.

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Information presentation

• Information presentation is concerned with
  presenting system information to system users
• The information may be presented directly or may
  be transformed in some way for presentation
• The Model-View-Controller approach is a way of
  supporting multiple presentations of data

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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.

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HCI design models

• The waterfall life cycle model.
• The star life cycle model.
• Rapid prototyping model.

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Design Process Models

• Waterfall model
• The waterfall model assumes that the design is
  fixed before entering to the next phase of
  design. Does not fit well in interactive
  systems. 
• It is a sequence of steps from software
  engineering field.
• Spiral model
• Only continue after step if feedback is positive.

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Waterfall Model( From Software Engineering Field
)
Initiation
Application Description
Analysis
Requirements Specification
Design
System Design
Implementation
Product
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The waterfall model

• Application description
• General description of the purpose and the
  functions of the system to be designed.
• Requirements specification
• Detailed description of the functions the system
  should perform.
• System design
• Defining the software functions and software
  modules.
• Product
• The resulting implementation of the system

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The star life cycle
Task analysis / functional analysis
Implementation
Evaluation
Prototyping
Requirements specification
Conceptual design / formal design
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The star life cycle

• The design of interactive systems typically does
  not follow a specific order of steps.
• The design can start in any step - followed by
  evaluation.
• Needs good software tools.

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Software prototyping

• A prototype is an initial version of a system
  used to demonstrate concepts and try out design
  options.
• Different kinds of prototyping
• Low fidelity.
• High fidelity.
• Compromises in prototyping
• Vertical.
• Horizontal.

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Why prototype?

• Evaluation and feedback are central to
  interaction design.
• Stakeholders can see, hold, interact with a
  prototype easily.
• Team members can communicate effectively.
• You can test out ideas for yourself .
• It encourages reflection very important aspect
  of design.
• Prototypes answer questions, and support
  designers in choosing between alternatives.

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Benefits of prototyping

• Improved system usability.
• A closer match to users real needs.
• Improved design quality.
• Improved maintainability.
• Reduced development effort.

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What to prototype?

• Work flow, task design.
• Screen layouts and information display.
• Difficult, controversial, critical areas.

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Low-fidelity(????? ????? ) Prototyping

• Uses a medium which is unlike the final medium,
  e.g. paper, cardboard.
• Is quick, cheap and easily changed.
• Examples sketches of screens, task sequences,
  storyboards, etc

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High-fidelity prototyping

• Uses materials that you would expect to be in the
  final product.
• Prototype looks more like the final system than a
  low-fidelity version.

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Compromises(???????? ) in prototyping

• Two common types of compromise
• Horizontal provide a wide range of functions,
  but with little details.
• Vertical provide a lot of details for only a few
  functions.
• Compromises in prototypes mustnt be ignored.

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The prototyping process
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Sketches

• Drawing of the outward(??????? ) appearance of
  the intended system.
• Sketching is important to low-fidelity
  prototyping

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Storyboard of a computer telephone
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Help-
Type name and place call
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UI design principles

• UI design must take account of the needs,
  experience and capabilities of the system users.
• Designers should be aware of peoples 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.

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Design principles

• User familiarity
• The interface should be based on user-oriented
  terms and concepts rather than computer
  concepts. For example, an office system should
  use concepts such as letters, documents, folders
  etc. rather than directories, file identifiers,
  etc.
• Consistency
• The system should display an appropriate level
  of consistency. Commands and menus should have
  the same format, command punctuation(??????? )
  should be similar, etc.
• Minimal surprise
• If a command operates in a known way, the user
  should be able to predict the operation of
  comparable commands.

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Design principles Cnt.

• 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.

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User interface design principles
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Interactive systems and software life cycle

• How to develop the Software ?
• Software is
• Large number of connected computer programs.
• High level of quality.

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Factors of Software Quality

• Correctness
• Reliable
• Robustness
• Friendly User Interface
• Modifiable
• Compatible
• Portable
• Interpretable
• Efficiency
• Well documented

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Request to develop SW
Yes
Feasibility Study
Requirement Engineering
Customer
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Requirement Engineering

• Requirement Elicitation.
• Requirement Analysis.
• Requirement Validation.
• Requirement Specification.

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Requirement Types

• Functional Requirement.
• Non-Functional Requirement.
• Data.
• Domain.
• Constraint.
• Glossary.

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Interactive systems

• After the iterative process, the result of the
  requirement engineering must be
• Clear.
• Accurate.
• Complete.

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Request to develop SW
Yes
Feasibility Study
Requirement Engineering
Customer
Architecture design
Problem
Solving
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Requirement Engineering Phases
Design
(1)
Domain understanding
(7)
Req. Specification
(2)
Req. Elicitation
(6)
Req. Validation
(3)
Req. Decomposition
(5)
Req. Prioritization
(4)
Conflict Resolution
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