Types of Disabilities, Part 1
In my experience, disabilities have been categorized in many different ways. Most commonly, I've seen them generalized in the following 4 categories:
In their Introduction to Web Accessibility article, WebAIM is an example of one source I've found these 4 categories outlined. The University of Illinois at Urbana-Champaign's An Introduction to Accessibility and Inclusive Design class uses the same broad categories.
In contrast, Deque's coursework addresses disabilities with more specific categories. They propose 13 categories altogether:
- Low Vision
- Color Blindness
- Auditory Disabilities
- Motor Disabilities
- Cognitive Disabilities
- Dyslexia/Reading Disabilities
- Math Disabilities
- Speech Disabilities
- Seizure Disorders
- Psychological/Psychiatric Disabilities
- Multiple/Compound Disabilities
In comparison, the CPACC Body of Knowledge breaks disability types into 9 categories:
- Mobility, flexibility, & body structure
So, for the sake of staying true to the study guide, let me tackle the first 4 on the CPACC list.
VisualPermalink for "Visual"
Visual disabilities can refer to blindness (of varying degrees), low vision, or colorblindness. Some of these communities prefer to be acknowledged as the specific disability (blind, low vision, or colorblind) rather than visually impaired. However, it's better to ask someone about their preferred label, rather than assuming one voice speaks for everyone.
BlindnessPermalink for "Blindness"
According to legal definition, a person is blind if they have a visual acuity of 20/200 or less with correction or who has a field of vision (what can be seen in front of the person) of 20 degrees or less in their "best" eye. In 2017 the World Health Organization (WHO) estimated 1 million people in the US and 36 million people worldwide are legally blind.
Some causes of blindness:
- Macular Degeneration
- Accidents or traumatic injuries to the eye
- Retinitis Pigmentosa
|Digital interfaces with screens||
|Inaccessible content or interface (not compatible with screen reader)||
|Walking independently to places||
|Flat interfaces and controls||
|Text on containers or packaging||
|Printed materials (text and images)||
Additional Reading about blindness:
- Accessibility, Augmented by Chancey Fleet
Low VisionPermalink for "Low Vision"
A person is considered to have low vision if their vision is 20/70 or poorer in their best eye with correction. People with low vision often struggle to accomplish visual tasks, but with the use of assistive technologies or adaptive strategies, they sometimes can accomplish those tasks. The National Institutes of Health estimates that there are 2.9 million people in the US and 246 million worldwide with low vision.
Types of low vision:
- blur (generalized haze)
- blur with low contrast (generalized haze)
- cataracts (generalized haze)
- diabetic retinopathy (central vision)
- glaucoma (central vision)
- hemianopia (peripheral vision)
- macular degeneration (central vision)
- retinal detachment (peripheral vision)
- aphakia (generalized haze)
- light sensitivity
- night blindness
On Day 51 of my WAS certification exam journey., I posted about Users with Low Vision, which expands on some of this information.
ColorblindnessPermalink for "Colorblindness"
Colorblindness is the inability to distinguish between certain kinds of colors, based on brightness and luminosity. 1 in 12 men and 1 in 200 women worldwide experience colorblindness.
Types of colorblindness:
- red-green, including red on black (Deuteranopia and Protanopia)
- blue-yellow (Tritanopia)
- grayscale (Achromatopsia)
|Color combinations with low contrast||
AuditoryPermalink for "Auditory"
Auditory disabilities range from mild to profound hearing loss and deafness. Some causes of auditory disabilities:
- premature birth
- ear trauma
- exposure to loud noises
|Speeches or presentations||
|Doorbells or other alarms||
DeafblindessPermalink for "Deafblindess"
Deafblindness is a combination of blindness and deafness. People who are deafblind encounter the same challenges as blind and deaf people would.
|Text or images||
|Video and/or audio||
Mobility, flexibility, & body structurePermalink for "Mobility, flexibility, & body structure"
People with mobility impairments may experience difficulty moving, controlling, or coordinating movements of the body. Some of these disabilities subcategorized as traumatic injuries (spinal cord injury, stroke, damage to limb) or biological conditions (CP, MD, Parkinson's, MS, ALS, RA).
Causes of mobility impairments may be due to:
- premature birth
|Steps and escalators||
|Door knobs, handles, entrances||
Additional reading about motor disabilities:
- The Squeaky Wheelchair blog by Kathleen Downes
- WAS Day 54: Users with Motoric Disabilities
- WAS Day 65: Identifying A11y Issues for Switch Control Users
To Be Continued...Permalink for "To Be Continued..."
This post only covers touches on some of the categories of disabilities. Next up, I'll be learning about cognitive, speech, seizure, psychological/psychiatric, and compound disabilities to share with you in Part 2.