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Usability and Interface Design


Usability might commonly be known as 'user friendliness', but from a designer's ... [1] Peck, Dave D (1999). Pocket guide to multimedia. Delmar Publishers, NY. Pp 36. ... – PowerPoint PPT presentation

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Title: Usability and Interface Design

Usability and Interface Design
  • To introduce
  • The importance of Usability of your Graphical
    User Interface
  • Interface Design Issues

Usability might commonly be known as user
friendliness, but from a designers point of
view Shneiderman (1992)1 defines usability as
combination of   q       Ease of
learning q       High speed of user task
performance q       Low user error rate q      
Subjective user satisfaction q       User
retention over time

1 Shneiderman B. (1992). Designing interface
strategies for effective human-computer
interaction. Reading, MA. Addison-Wesley.
  • Larry L. Constantine, IDSA, Chief Scientist, is
    one of the pioneers of software design whose
    current work in usage-centered design continues a
    long tradition of technical innovation and
    professional leadership.
  • Jakob Nielsen, Ph.D., is a User Advocate and
    principal of the Nielsen Norman Group.

Constantines Usability Principles
  • Structure Principle 
  • Organise the user interface purposefully, in
    meaningful and useful ways that put related
    things together and separate unrelated things. 
  • Simplicity Principle 
  • Make simple, common tasks simple to do,
    communicate simply in the user's own language and
    provide good shortcuts that are meaningfully
    related to longer procedures. 

Constantines Usability Principles
  • Visibility Principle 
  • Keep all needed options and materials for a given
    task visible without distracting the user with
    extraneous or redundant information. 
  • Feedback Principle 
  • Keep users informed of actions or
    interpretations, changes of state or condition,
    and errors or exceptions using clear, concise,
    and unambiguous language familiar to users. 

Constantines Usability Principles
  • Tolerance Principle 
  • Be flexible and tolerant, reducing mistakes by
    allowing undoing and redoing--cancelling and
    going back.  
  • Reuse Principle 
  • Reduce the need for users to rethink and remember
    by reusing internal and external components and
    behaviours, maintaining consistency with purpose
    rather than merely arbitrary consistency.
    Maintain consistency in icons and heading styles
    to offer visual cues to user's location in the
    information space.

Nielsens Usability Rules
  • Visibility of project status
  • The project should always keep users informed
    about what is going on. e.g. Provide Thank
    yous" when forms are submitted.
  • Match between project and real world 
  • Follow real-world conventions, making information
    appear in a natural and logical order. Metaphors
    help shopping, changing a channel, etc.

Nielsens Usability Rules
  • User control and freedom
  • Support undo and redo.
  • Consistency and standards 
  • Users should not have to wonder whether different
    words, situations, or icons mean the same thing.
    Follow conventions.

Nielsens Usability Rules
  • Error prevention 
  • Prevent a problem from occurring in the first
  • Recognition rather than recall
  • The user should not have to remember information
    from one part of the project to another. 
  • Aesthetic and minimalist design 
  • Every extra unit of information in a dialogue
    competes with the relevant units of information
    and diminishes their relative visibility.

Nielsens Usability Rules
  • Help and documentation 
  • Even though it is better if your project can be
    used without documentation, it may be necessary
    to provide help and documentation.

Usability Testing
  • Usability testing is a process that can be used
    throughout the development of multimedia software
    or any other.
  • The purpose of testing is to find problems and
    make improvements to the project during its
    design and development.  

  • For developing effective interactive multimedia
    software, dimensions of usability testing were
    classified into the general categories of
  •  learnability
  •  performance effectiveness
  •  flexibility
  •  error tolerance and system integrity and
  • user satisfaction.

Usability Checklist
  • Relevance 
  • Quality
  • Consistency
  • Navigation

Checking Usability
  • Paper prototyping.
  • Sit down and walk through the project. Draw, with
    pencil and paper, the screens include
    navigation,drop-down lists, etc.
  • Develop scenarios - "step through" them using the
    paper prototype
  • Refine/redevelop as necessary paper is cheap!
  • Create for the user.
  • Test with real people.
  • Honour feedback.
  • Learn and apply standards.
  • Commit to quality.

Typical Usability Problems
  • Bloated page design that has too many elements
  • Internally focused design that hypes technology
    without giving any real information
  • Obscure site structure that has no logical
  • Lack of navigation support, making it very hard
    to find things when combined with an obscure site
  • Writing style optimised for print and linear
    reading, not for the way users read on screen
    (they dont, they scan). (Neilson, 1998)1
    1 Neilsen J (1994). Heuristic Evaluation. In
    J Neilsen R Mack (Eds), Usability Inspection
    Methods, NY John Wiley and Sons, Inc.

Interface Design
What is design?   Design sometimes refers to the
manner in which the pieces are put together, such
as the way a presentation will be displayed, on
what products, and in what environment. All of
these aspects reflect design considerations.1  

1 Peck, Dave D (1999). Pocket guide to
multimedia. Delmar Publishers, NY. Pp 36.
Interface Design
  • In databases, the interface refers to what the
    user sees on a screen. The interface is the
    interaction of the person to the screen. An
    interface can apply to a wide range of
    applications such as
  • Multimedia presentations
  • CD-ROM publishing
  • Computer based training
  • Web pages
  • Database GUIs

Interface Design
Interface design is a part discipline (following
conventions and good design principles). Design
is part science (usability). Design is part art
(creating screen layouts that are informative,
intuitive and visually pleasing).
Interface Design
What is interactivity?  Interactivity, refers to
an action that the user makes to control the
events being viewed on the screen.1
  • A record may be saved.
  • New screen opened.
  • Exit the application.

1 Peck, Dave D (1999). Pocket guide to
multimedia. Delmar Publishers, NY. Pp 197.
Interface Design
  • Designing for differences
  • Disabilities
  • Cultural issues
  • Factors for success
  • The following concepts contribute to the success
    of an interface
  • user-centred design
  • the power of event-driven programming
  • Affordances, Metaphors, and Manipulation

Interface Design Principles and Guidelines
  • Be consistent Effort may be required by the
    designer to ensure that this consistency is
    achieved, it requires attention to detail.
  • Use similar objects to perform similar functions
    throughout your product. That way, what users
    learn in one screen they can use in another. This
    quality helps users learn quickly and builds
    their confidence.
  • Present lists in useful orders
  • Arrange information in logical groups Clustering
    (and aligning) objects so that those which belong
    together are seen together enhances the meaning
    of the components.

Interface Design Principles and Guidelines
  • Minimise pointer movement
  • If one button responds to a single mouse click
    then every button should respond to a single
  • Let the user control the interaction
  • Give immediate, obvious feedback for every user
  • Use sound, colour, animation and multimedia clips

Interface Design Navigation Elements
  • Buttons
  • Menus
  • Icons
  • Drop-down lists

Basic Concepts
  • Human Perception
  • The use of balance
  • The use of harmony when expectancy, patterns,
    and balance are used together, they should create

Basic Concepts
  • You have been introduced to Usability Issues.
  • Each element of the interface you create should
    be designed with Usability in mind.

  • Read chapter on Usability
  • Practice creating Queries using the QBE grid.

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