CS 407 Human Computer Interface

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CS 407 Human Computer Interface

• Class 12
• Wednesday, September 22, 1999

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Thought for the Day

• Where is the wisdom we have lost in knowledge?
• Where is the knowledge we have lost in
  information?
• -T.S. Eliot

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Todays Topics

• Start Chapter 3
• Any questions on Project?

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Reading Quiz

• List 3 interaction styles.
• Define either
• Gulf of execution, or
• Gulf of evaluation.
• What does WIMP stand for?
• Draw a line, confer.
• Draw a line, check the text

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Chapter 3 The Interaction

• Interaction Frameworks
• Ergonomics
• Interaction Styles
• Context of Interaction

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Interaction Frameworks

• Interaction the communication between the user
  and the system.
• Why have a framework?
• It allows contextualization.
• It presents a global view.

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Don Normans Interaction Framework

• User establishes the goal
• Formulates the intention
• Specifies actions at the interface
• Executes the action
• Perceives system state
• Interprets system state
• Evaluates system state with respect to the goal.

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Gulfs in the Framework

• Gulf of Execution  users formulation of actions
  may be different from those actions allowed by
  the system.
• Gulf of Evaluation - users expectation of the
  changed system state may be different from the
  actual presentation of this state.
• Normans model concentrates on users view of the
  interface only.

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Normans Framework, Extended by Aboud Beale

• User
• Input
• System
• Output

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Extended Framework

• Gulf of Execution
• Gulf of Evaluation

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Extended Framework (2)

• Articulation

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Extended Framework (3)

• Articulation
• Performance

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Extended Framework (4)

• Articulation
• Performance
• Presentation

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Extended Framework (5)

• Articulation
• Performance
• Presentation
• Observation

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Extended Framework (6)

• Articulation, Performance, Presentation,
  Observation.
• Each has its own unique language.
• Interaction necessitates translation between
  languages.
• This translation is often difficult or even
  impossible!

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Framework of Interaction

• Not restricted to computer systems!
• Identifies all major components or players in
  interaction.
• Allows comparative assessment of systems.
• It is an abstraction! (It leaves out the details
  ? both good and bad!)

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Ergonomics

• Study of the physical characteristics of
  interaction. (Human Factors).
• Considers
• Arrangement of controls displays.
• Surrounding environment
• Health issues.
• Use of Color

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Interaction Styles

• Command line interface
• Menus
• Natural language
• Question/Answer and Query Dialogue
• Form Fill-in and Spreadsheets
• WIMP
• others
• Each has advantages disadvantages!

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Command Line Interfaces

• Way of expressing instructions to the computer
  directly. Can be function keys, single
  characters, short abbreviations, whole words, or
  a combination.
• Suitable for repetitive tasks.
• Better for expert users than novices.
• Offer direct access to system functionality.
• Command names, abbreviations should be meaningful.

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CLI (Command Line Interface)

• Advantages
• Powerful
• Flexible, User controlled
• Fast Efficient
• Minimal use of screen real estate

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CLI (Command Line Interface)

• Disadvantages
• Difficult to learn.
• Difficult to remember (recall, not recognition
  memory).
• Assumes typing skill.
• Error prone.
• Enhancements are invisible.

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CLI

• Dont give in to the temptation Old, obsolete,
  useless!
• CLI is often the BEST interface for certain users
  tasks.
• CLI can be function keys, or single keystrokes.
  Dont just think of the command languages youve
  seen before!