Practical Guide to Website Usability
Web usability is an approach to designing effective websites that take into account human limitations. It is all about effectiveness of presenting information using internet technologies. “Web Designers should take into account the basic abilities of all potential users.” (Bailey, 1996, p. 69). The information contained in this article will help designers make pages accessible for all persons regardless of their human limitations. “âÂ?¦making [web]sites accessible helps make them more usable for everyone.” (Grossman, 2004). This project was designed to determine the features of a website that will make it accessible to users, regardless of their limitations.
This article is a resource that permits users to learn about how to make websites accessible while displaying may accessibility principles on its pages.
User Limitations
There are three types of user limitations: cognitive processing, sensory, and physical abilities.
Cognitive Processing
Memory
Designers should strive to create sites that do not overload the users’ memory. Sites with low memory loads will permit the user to navigate and learn the site more efficiently.
There are three categories of memory: Sensory, Short Term and Long Term.
Sensory Memory
Sensory memory is our ability to retain impressions of sensory information after the original stimulus has ceased. In one condition, participants can be asked to report as many letters as they could remember after the letters had been presented to them. After the presentation of letters, the participants can be asked to recall a particular row of letters (first, second or third). Sperling found that some participants could only report an average of four letters in the first condition, they usually successfully recalled the four letters of the chosen row in the second condition, even though they were only told which to report after the whole letter grid was presented. This is an example of sensory memory. Information must first pass through sensory memory before entering short and term memory.
One can apply knowledge of sensory memory to design better web pages. Pages can be made to load in stages causing the user to perceive the page is loading faster.
Short Term Memory
Short – term memory, sometimes referred to as “primary” or “active” memory, is that part of memory which stores a limited amount of information for a limited amount of time (roughly 30-45 seconds). The way any website is organized can influence how quickly and easily the user will be able to navigate through a website and find the information that they are searching for.
Short term memory is information held in short-term memory may be: recently processed sensory input; items recently retrieved from long-term memory; or the result of recent mental processing. More information can be more effectively remembered and recalled if items are “chunked” together in groups. Recent studies indicate short term memory may be expanded by using visual and auditory cues.
Short term memory limitations are especially important when considering web page navigation. It is better to create sites with broad menu or navigation bar selections, each two or less levels deep rather than menu or navigation bar selections with few selections each selection multiple levels in depth. Information should be “chunked.”
Long Term Memory
Long-term memory is memory that can last as little as 30 seconds or as long as decades. It differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 30 seconds. long-term memory is subject to fading in the natural forgetting process, or may even be altered or degraded by injury.
Cuing and consistency can be used to make websites more usable. For example, job aids in training programs can be used as cues that may help the user recall information that exists in long term memory. Consistency throughout a website will help users remember and recall information stored in long term memory to help them use the site. If website layout, navigation and icons are consistent, experienced users will be able to apply what they already learned when using the site. This should be considered when updating a site and creating new site pages.
Mental Ability
Designers should consider user mental ability when creating websites. By designing for users with learning disabilities, attention disorders, developmental disabilities and neurological impairments will make websites more accessible.
Learning Disabilities
Learning disability is used to refer to socio-biological conditions that affect a persons communicative capacities and potential to learn. Dyslexia is a type of learning disability that affects how an individual perceives words. People with dyslexia must apply special techniques in order to read written or printed text.
Design principles to follow to web pages more usable for people with dyslexia are very similar to designing pages for partially sighted users. Choosing fonts and colors that make pages easier to read will help users with dyslexia. Some dyslexics use text readers to help them browse the Internet so design techniques for blind users can be applied.
Attention Disorders
Attention deficit disorder (ADD), attention deficit hyperactivity disorder (ADHD) affect the a person’s ability to focus attention on a particular task. People with this condition are sometimes easily distracted when interacting with websites.
In addition to applying sound design principles in color selection and page organization, moving or flashing text or graphics should be avoided unless absolutely needed and if used, text alternatives should be employed or the user should be given the option to turn off the animation.
Learning Disabilities
Down’s Syndrome, fragile x, autism, and cerebral palsy are all examples of developmental disabilities.
Neurological impairments may be caused by brain injury or disease. Traumatic brain damage and strokes are examples of brain injury. Alzheimer’s and dementia are examples of brain disease.
These conditions can impact how a user interacts with websites.
Consistent, well organized pages, and simple navigation are fundamental usability design principles that will help individuals with developmental disabilities and neurological impairments use websites. If appropriate, use of graphics or icons to supplement text and assist in navigation will also help users with developmental disabilities and neurological impairments. These two conditions may also affect memory and cause physical limitations.
Sensory
Vision
Designers must consider several factors when designing sites that will be accessible to the visually impaired. Users may differ in the way they perceive color due to color blindness or deficiency. Users may be partially sighted due to factors such as age, disease, or medication use. Blind users will likely rely on alternate browsing methods to access websites.
Color Blindness.
Color blindness is the reduced ability to discriminate between colors, especially shades of red and green. It is usually hereditary, and is more likely to affect males than females. Move your mouse over the image on the right to see an example of how strawberries appear to someone who is red/green colorblind.
Web pages should be designed with alternate coding schemes if color coding is used. An example of this can be found at the top of this page in the site navigation bar. Each tab with linked text has a gray background except for the tab of the page the user is currently on. Either the tabs have a color background or not. This makes it easier for the user to determine which page the user is on.
A traffic light is another example of alternate coding. Light position is used as an alternate coding for light color. Red is always at the top and green is always at the bottom of traffic lights so one does not have to be able to be able to distinguish between the two to safely follow the signal.
Partially Sighted
Sight can be degraded by a number of different factors. Persons may be born with poor vision or their vision may be reduced by age, disease, injury, drug use, or fatigue (to name a few). Partially sighted users may find websites difficult to use if the pages are not designed properly. Move your mouse over the image at the right to see how a street scene may appear to someone with cataracts.
Font size, style, color and contrast will affect how easy a user will be able to read text on websites. (This site uses Arial Bold that scales to the users screen size.) Some web browsers will permit a user to set font size preferences. Care still must be taken to ensure the font is large enough, of a style that users will find easy to read, and contrasts properly with the background.
Blindness
Can you effectively use a website without looking at your computer screen? Blind users must use alternate means of website navigation. They may use screen reader software to navigate the Internet. Screen reader software runs Braille or text-to-speech browsers.
In order to ensure web pages will be read properly by screen reader software, the designer can edit the HTML code to ensure it is tagged properly. Once this step is complete, one can test the site using one of several websites that provide this service free of charge. All graphics used should have alternate text describing them.
Hearing
Hearing can be lost or degraded for a number of reasons. Website Designers should consider a user’s ability to perceive sound when creating web pages.
Sound should only be used as an alternate means of cuing or alerting the user. If streaming audio or video is used, alternate text must be used. Alternate text may be provided via transcript or scrolling text. If scrolling text is used, the user should be given the option to turn it off as users with attention disorders may find scrolling text distracting.
Physical Abilities
Physical limitations can be caused by a number of conditions including traumatic injury, developmental disabilities and neurological impairments.
Persons with physical limitations, such as being a quadriplegic, may have difficulty using a mouse, keyboard. There are technologies that can assist such individuals, such as sip and puff switches, eye tracking devices or voice activated software. Web designers should ensure all keyboard functions are available for accessing websites since most assistive technologies for users with physical limitations work through or emulate keyboards. Pages should be well organized, consistent and any buttons and links should be large enough for the user to easily view and select.
Design Rules
There are a wide range of Website design rules available on the Internet, many of which are not based on academic research. Levi & Conrad Usability Principles and Chisholm, Vanderheiden, & Jacobs Web Content Accessibility Guidelines are based on research and are available on this page. Here are a listing of usability principles by Levi & Conrad (2002) that you can use when designing your next website.
1. Speak the users’ language. Use words, phrases, and concepts familiar to the user. Present information in a natural and logical order.
2. Be Consistent. Indicate similar concepts through identical terminology and graphics. Adhere to uniform conventions for layout, formatting, typefaces, labeling, etc.
3. Minimize the users’ memory load. Take advantage of recognition rather than recall. Do not force users to remember key information across documents.
4. Build flexible and efficient systems. Accommodate a range of user sophistication and diverse user goals. Provide instructions where useful. Lay out screens so that frequently accessed information is easily found.
5. Design aesthetic and minimalist systems. Create visually pleasing displays. Eliminate information which is irrelevant or distracting.
6. Use chunking. Write material so that documents are short and contain exactly one topic. Do not force the user to access multiple documents to complete a single thought.
7. Provide progressive levels of detail. Organize information hierarchically, with more general information appearing before more specific detail. Encourage the user to delve as deeply as needed, but to stop whenever sufficient information has been received.
8. Give navigational feedback. Facilitate jumping between related topics. Allow the user to determine her/his current position in the document structure. Make it easy to return to an initial state.
9. Don’t lie to the user. Eliminate erroneous or misleading links. Do not refer to missing information.
Web Content Accessibility Guidelines from Chisholm, Vanderheiden, & Jacobs (1999)
1. Provide equivalent alternatives to auditory and visual content.
2. Don’t rely on color alone.
3. Use markup and style sheets and do so properly.
4. Clarify natural language usage
5. Create tables that transform gracefully.
6. Ensure that pages featuring new technologies transform gracefully.
7. Ensure user control of time-sensitive content changes.
8. Ensure direct accessibility of embedded user interfaces.
9. Design for device-independence.
10. Use interim solutions.
11. Use W3C technologies and guidelines.
12. Provide context and orientation information.
13. Provide clear navigation mechanisms.
14. Ensure that documents are clear and simple.
