User Interface Design

User Interface Design-Software egineering

User Interface Design

Interface Design

Easy to learn ?

Easy to use?

Easy to understand?

Typical Design Errors

  • Lack of consistency
  • Too much memorization
  • No guidance / help
  • No context sensitivity
  • Poor response
  • Unfriendly

Golden Rules

  • Place the user in control
  • Reduce the user’s memory load
  • Make the interface consistent

Place the User in Control

  • Provide for flexible interaction.
  • 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.

Reduce the User’s Memory Load

  • Reduce demand on short-term memory.
  • Establish meaningful names.
  • Define shortcuts.
  • The visual layout of the interface should be based on a real world metaphor.
  • Disclose information in a progressive fashion.

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.

User Interface Design Models

  • User model — a profile of all end users of the system
  • Design model — a design realization of the user model
  • Mental model (system perception) the user’s mental image of what the interface is
  • Implementation model — the interface look and feel coupled with supporting information that describe interface syntax and semantics

User Interface Design Process

Interface Analysis

Interface analysis means understanding :

  • the people (end-users) who will interact with the system through the interface
  • the tasks that end-users must perform to do their work,
  • the content that is presented as part of the interface
  • the environment in which these tasks will be conducted.
  • Are users trained professionals, technician, 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?
  • How are users compensated for the work they perform?
  • Do users work normal office hours or do they work until the job is done?
  • 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?

Task Analysis and Modeling

Task Analysis answers 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?
  • Workflow analysis defines how a work process is completed when several people (and roles) are involved
  • What is the hierarchy of tasks?
  • Use-cases define basic interaction

Analysis of Display 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 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?

Design Evaluation Cycle

Interface Design Patterns

  • Patterns are available for

–The complete UI

–Page layout

–Forms and input



–Page elements


Design Issues

  • Response time
  • Help facilities
  • Error handling
  • Menu
  • Application accessibility




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