Web Accessibility – Types of Disability
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Reading Time: 6 minutesThe key to a full understanding of web accessibility is an understanding of the different types of disability or impairment and how those who live with those impairments cope with using the internet. These requirements are what drive the WCAG2.0 accessibility guidelines – why they have come about, and why they’re important.
Some people believe that accessibility is just about blind users with screen readers. Whilst people who are blind and others with sight impairments do have significant issues with using the internet they are not the only ones.
This post will attempt to touch on all the significant types of disability and describe some of the ways each group will interact with the web – whether by amending options in a browser or by using assistive technology of some sort eg screen readers.
Since I do not have any disabilities myself my knowledge is gained from working with people with disabilities and from research. If you feel I have made a mistake with any of the points in this post please let me know by leaving a comment.
Visual impairments
In the course of my work as an accessibility consultant and trainer I still come across many people who simply assume that the blind are unable to use the internet. I guess that many of these people haven’t really thought about how those with blindness actually cope with day-to-day tasks in the web and computer based world.
Visual impairments covers a wide spectrum of conditions – from ‘low-vision’ or ‘partially sighted’ through to ‘total blindness’. There are other visual conditions such as the different forms of colour blindness.
Low vision or partial sight
People with low vision may suffer from extreme forms of short-sightedness or long-sightedness, or their vision may be blurred or unclear in other ways.
Screen reader brands
When interacting with websites people with low vision may typically need to do one or more of the following:
- Adjust the size of the text on their browser
- Use assistive software to magnify the web page
- Override the style of web pages to use high contrast colour schemes
- Use screen readers and/or braille display
The following features of web pages can make life difficult for people with low vision (not an exhaustive list):
- Fixed height text that cannot be resized
- Semantically connected items that are some distance apart – eg form labels and input boxes too far apart
- Insufficient colour contrast
- Busy page backgrounds
- Use of colour only to convey meaning
- Dynamic updating of content some distance from focus
Blindness
Blindness itself has degrees and there is a legal measure in a number of countries. People who are ‘legally blind’ may still have some residual vision or only the ability to tell light from dark. Typically blind users will have extreme difficulty using websites as sighted people would.
Braille display with keyboard - from Wikipedia
When interacting with websites people with blindness may typically need to do one or more of the following:
- Use a screen reader
- Use a braille display
The following features of web pages can make life difficult for people with blindness (not an exhaustive list):
- Images without appropriate alternate text
- Badly or inappropriately marked up pages, forms etc
- Poorly worded links
- Pages with incorrect or non-unique titles
- Pages without headings (See Using Headings Properly)
- PDFs that are not created with accessibility in mind
- AJAX updates of pages
- Flash, Java and other RIA functionality
Colourblindness
Colourblindness test
A common misconception is that people with colourblindness only see in black and white (or greyscale). Whilst that is true of one form there are many types of colourblindness and each one has differing effects on people’s perception of colour. Colourblindness is much more common in men than women.
Mostly when interacting with websites people with colourblindness won’t need to use any special techniques or software. However the following features of web pages can make life difficult for people with colourblindness (not an exhaustive list):
- Insufficient colour contrast between text and background
- The use of colours alone to indicate meaning
Motor impairments
Motor impairments take many forms and I don’t intend to cover all of them here. But these impairments can affect the use of people upper limbs and hands – the way most people interact with a computer and web.
People with motor impairments may need to do one or more of the following to access the web:
- Rely solely on keyboard interaction with web pages
- Use specialised keyboards, switches or other input devices
- Use voice recognition software
- Use head pointers or eye gaze systems
The following features of web pages can make life difficult for people with motor impairments (not an exhaustive list):
- Functionality that cannot be operated by keyboard interaction
- Pages where keyboard focus is not clearly indicated
- Links or form objects (eg radio buttons) that have a small target area
- Redirects to another page or page element triggered solely by changing values in a dropdown box (select)
- Automated redirection of keyboard focus away from a page element
- Inappropriate tab order on the page
- Absence of visual skip links (See Providing Skip Links in Your Pages)
- Sites that require quick responses
Hearing impairments or deafness
British Sign Language - © RNID.org
Like blindness, deafness can manifest itself in infinite degree – from slight impairment to complete loss of sensation.
It is a common misconception that as the web is a significantly visual medium those who suffer from deafness shouldn’t have many problems with the internet. But of course the web is becoming an increasingly multimedia experience and those suffering with deafness are not well catered for.
Those who have been profoundly deaf since birth or an early age may have a sign language (eg British Sign Language or BSL) as their first or only language. Sign languages may not be as complex as spoken languages and so complex textual concepts may be difficult to understand.
The following features of web pages can make life difficult for people with deafness (not an exhaustive list):
- Video content with no captioning
- Audio content or signals with no captioning
- Background noises too loud
- Very complex and/or obscure language
Cognitive Impairments
Cognitive impairments is a very broad grouping encompassing a number of conditions. They include language-based difficulties such as dyslexia, intellectual disabilities and other conditions such as autism or attention deficit hyperactivity disorder (ADHD).
Dyslexia
People with dyslexia impairments may need to do one or more of the following to access the web:
- Use screen readers or other text to speech software
The following features of web pages can make life difficult for people with dyslexia (not an exhaustive list):
- Using wide columns of text or large blocks of text.
- Justified text or text that has uneven gaps between words
- Pure white page backgrounds
- Text styles featuring serifs – eg Times New Roman
- Italic text or very small text
- Moving or flickering images/effects
Other cognitive conditions
The following features of web pages can make life difficult for people with cognitive impairments (not an exhaustive list):
- Long sentences and complex language
- Insufficient instructions on how to use functionality (forms, applications etc) or what they’re for
- Pages that require quick response
- Sites that have inconsistent page layout/navigation
- Sites that change layout or structure frequently
- Pages that update content unexpectedly
Epilepsy
Epileptic seizures can be triggered by flashing or strobe lights at certain frequencies. They can also be triggered by flickering or blinking content in web pages so it is important that websites do not present such content.
Anyone else?
If you feel I’ve omitted a disability group that has issue with web accessibility please let me know by leaving a comment below or our Contact Us form if you prefer.
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