Lesson 4

• All the ways the user can communicate or otherwise interact with the computer system.

  1. Command language
  2. Menu Selection
  3. Form fill-in
  4. Natural language
  5. Direct Manipulation
• (Advantages)

  • Flexible
  • Appeals to expert users
  • Supports creation of user-defined "scripts" or macros
  • Is suitable for interacting with networked computers even with low bandwidth

  Command Language
• (Disadvantages)

  • Retention of commands is generally very poor
  • Learnability of commands is very poor
  • Error rates are high
  • Error messages and assistance are hard to provide because of the diversity of possibilities plus the complexity of mapping from tasks to interface concepts and syntax
  • Not suitable for non-expert users

  Command language
• Advantages:

  • Simplifies data entry
  • Shortens learning in that the fields are pre-defined and need only be 'recognized'
  • Guides the user via the pre-defined rules

  Form fill-in
• Disadvantages:

  • Consumes screen space
  • Usually sets the scene for rigid formalization of the business processes

  Form Fill-in
• Advantages:

  • Ideal for novice or intermittent users
  • Can appeal to expert users if display and selection mechanisms are rapid and if appropriate "shortcuts" are implemented
  • Affords exploration (Users can look around in the menus for the appropriate command)
  • Structures decision making
  • Structures decision making
  • Allows easy support of error handling as the users input does not have to be parsed

  Menu Selection
• Disadvantage:

  • Too many menus may lead to information overload or complexity of discouraging proportions
  • May be slow for frequent users
  • May not be suited for small graphic displays

  Menu Selection
• Advantages:

  • Intuitive and potentially powerful
  • Can be used for simple interactions

  Disadvantages:

  • Technological limitations
  • Ambiguity

  Natural Language
• • Visibility of objects of interests
  • Rapid, reversible incremental actions performed directly on them
  • Replacement of complex command language by object of interest
  • Tries to bridge gulf of execution and evaluation

  Direct Manipulation
• Advantage:

  • Visually presents task concepts
  • Easy to learn
  • Errors can be avoided more easily
  • Encourages exploration
  • High subjective satisfaction
  • Recognition memory (as opposed to cued or free recall memory)

  Direct Manipulation
• Disadvantages:

  • May be more difficult to program
  • Not suitable for small group displays
  • Spatial and visual representation is not always preferable
  • Metaphors can be misleading since the essence of metaphor is understanding and experiencing one kind of thing in terms of another
  • Compact notations may be better suit expert users

  Direct Manipulation
• Disadvantages:

  • May be more difficult to program
  • Not suitable for small group displays
  • Spatial and visual representation is not always preferable
  • Metaphors can be misleading since the essence of metaphor is understanding and experiencing one kind of thing in terms of another
  • Compact notations may be better suit expert users

  Direct Manipulation