Universal Design: A philosophy of design:

Universal design, or Inclusive Design is simply design intended for all to use and enjoy. Accessibility, usability and readability are important concepts of inclusive design –an area of Human-Computer Interface design, and are loosely defined below:

Accessibility

Perceptibility: design achieved for all to perceive, regardless of sensory abilities. To achieve this, provide redundant alternatives. (i.e. text, visual, auditory). For example, when including an image in a web page, provide an ‘alternative description of the image’ known as -ALT text.

Operability: design achieved for all to use, regardless of physical abilities. A few guidelines to achieve this are: minimize repetitive tasks and the need for physical exertion, provide hotspots or target areas that are big enough for track ball pointers or other assistive devices; and provide compatible design for wheelchair access (i.e. position controls for seated and standing users) and adaptive technologies.

Simplicity: design that is easy to use or understand, regardless of a user’s experience, literacy, or ability to focus. A few guidelines to achieve this are: eliminate unnecessary complexity, be clear; use consistent codes, controls and modes of operation; provide only relevant information and controls; provide clear prompts and feedback for all actions; and accommodate all levels of literacy (including media literacy).

Forgiveness: minimize the likelihood of user errors. A few guidelines to achieve this are: design controls that can be interpreted and used only one way to prevent errors from occurring; use warnings (alerts) and confirmations to reduce errors from occurring; include reversible actions to minimize the consequence of the error. (e.g. ‘undo’)

UsabilityAccording to usability guru, Jacob Nielsen, “Usability is a quality attribute that assesses how easy user interfaces are to use. The word “usability” also refers to methods for improving ease-of-use during the design process.”

Nielsen’s concept of Usability is defined by the following five qualities:

* Learnability: How easy is it for users to do basic tasks the first time they encounter the design?
* Efficiency: Once users have learned the design, how quickly can they perform tasks?
* Memorability: When users return to the design after a while of not using it, how easily can they remember how to do what they did the last time they encountered the design?
* Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
* Satisfaction: How pleasant is it to use the design?

References:

Jacob Nielsen’s The Alert Box, Usability 101: Introduction to Usability
http://www.useit.com/alertbox/20030825.html

Universal Principles of Design, by Lidwell, Holden and Butler. Rockport Publishers (2003)

Special thanks to Jutta Treviranus and the Adaptive Technology Resource Centre, for helping to raise my awareness of accessibility issues. Having worked for the ATRC for nearly a decade, I gained first-hand knowledge and experience that could never have been taught by any book or classroom setting!

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