Human Computer Interaction

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• Human Computer Interaction

Design Issues
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What is Human Computer Interaction ?

• Definition 1 - A discipline concerned with the
  design, evaluation and implementation of
  interactive computing systems for human use and
  the study of major phenomena surrounding them.
• Definition 2 - The study of people, computer
  technology, the ways these influence each other
  and how we can make this computer technology more
  usable by people.

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categories of interface

• Command Line
• Menu-driven
• Prompted User Interface
• Graphical User Interface

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Command Line
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Menu-driven
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HCI

• Prompted User Interface
• Video timer programmer
• ATM, auto banking machine
• Graphical User Interface
• Windows
• Mac
• XWindows

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HCI

• Interface model
• Presentation to the user.
• The interface
• Domain model
• The actual content or subject matter
• One domain model can have several interface models

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HCI Issues

• I/O devices
• Cognitive characteristics of user
• Background of the users
• Tasks
• Types of interface available

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Separation of domain and interface model

• copy cmywork.txt a
• underlying operating system commands, interrupt
  service routines, process management
• Windows...

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Design for users

• Importance of good user centered design
• Contribution of other academic disciplines
• psychology
• sociology
• linguistics
• others

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Good interface development

• Low level issues
• User needs analysis
• What tasks will be performed
• Where will the system be used
• Leads to usability index...

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Normans Design Principles

• Affordance
• Feedback
• Visibility

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Interface metaphors

• Representations of recognisable objects
• Users experience of reality

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Direct manipulation

• Interact with the object of interest
• (with a representation)
• no need to remember textual descriptions of items
• easy to learn, very usable and often well liked
• good feedback, affordance and visibility
• allows the creation of interface metaphors which
  lead to an intuitive interface

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Characteristics of DM

• elements should be visible
• operations should be straightforward (rapid) and
  reversible
• small operation incrementally causes big
  effects
• no need to revert to command language

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User Needs Analysis

• Task
• Person (partially blind)
• Situation(environment or application)

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Visualisation

• Translate large mental load into comprehensible
  visual image
• Improvements in sound and other technologies
  preferred term
• perceptualisation

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Perceptualisation (Perceptual User Interface)

• Definition - Perceptual interfaces are ones in
  which the computer is given the ability to sense
  and produce analogs of the human senses, such as
  allowing computers a sense of touch and force
  feedback.

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Accessibility(A category of usability

• Definition2 - Removal of barriers that prevent
  people with disabilities from participating in
  substantial life activities,ie Information
  technology.
• Definition2 - Enables successful access to
  information and encourages the use of information
  technology.eg. Partially blind persons

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Design for Access Average user

• Accessibility is usability which allows the user
  to effectively efficiently work on a system.
• Eg. Design of the talking book, led to the tape
  being created.