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:

  • visual
  • hearing
  • mobility
  • cognitive

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:

  • Blindness
  • Low Vision
  • Color Blindness
  • Deafblindness
  • 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:

  • Visual
  • Auditory
  • Deafblindess
  • Mobility, flexibility, & body structure
  • Cognitive
  • Speech
  • Seizures
  • Psychological/psychiatric
  • Multiple/compound

So, for the sake of staying true to the study guide, let me tackle the first 4 on the CPACC list.

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.

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:

  • Congenital
  • Cataracts
  • Diabetes
  • Macular Degeneration
  • Glaucoma
  • Accidents or traumatic injuries to the eye
  • Stroke
  • Retinitis Pigmentosa
Digital Environments
Challenge Solution
Digital interfaces with screens
  • Screen reader
  • Interface with built-in audio or speech
  • Refreshable Braille
Inaccessible content or interface (not compatible with screen reader)
  • Designers & authors can make markup for websites and content compatible with AT.
Physical Environments
Challenge Solution
Walking independently to places
  • White cane
  • Service animal
  • GPS-based walking instructions
  • Raised tiles on the ground
  • Obstructions removed from walkways and overhangs
Signage
  • Map & geolocation apps
  • Braille labels
  • Tactile models
Consumer Products
Challenge Solution
Flat interfaces and controls
  • Tactile controls
  • Audio interface
  • Mobile app control
Text on containers or packaging
  • Braille labels
Currency
  • Mobile app to read currency
  • Redesign of currency
  • Non-cash systems of payment
Printed materials (text and images)
  • Optical character recognition software
  • Conversion to digital format
  • Conversion to Braille

Additional Reading about blindness:

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
Physical and Digital Environments
Challenge Solution
Small text
  • Screen magnifier
  • Software or settings to increase contrast
  • Screen reader
  • Interface with built-in speech
  • Large print
  • Digital format compatible with AT
Low contrast
  • Software or settings to increase contrast
  • Designers and content creators choose high contrast for readability

On Day 51 of my WAS certification exam journey., I posted about Users with Low Vision, which expands on some of this information.

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)
Physical and Digital Environments
Challenge Solution
Color combinations with low contrast
  • Designers shouldn’t depend on color only to share information

Auditory

Auditory disabilities range from mild to profound hearing loss and deafness. Some causes of auditory disabilities:

  • genetics
  • congenital
  • premature birth
  • infections/illnesses
  • ear trauma
  • exposure to loud noises
  • aging
Digital Environments
Challenge Solution
Audio
  • Full transcript
  • Sign language interpretation
Video
  • Synchronized captions
  • Full transcript
  • Sign language interpretation
Physical and Digital Environments
Challenge Solution
Speeches or presentations
  • Sign language interpretation
  • Live captions
Physical Environments or Consumer Products
Challenge Solution
Doorbells or other alarms
  • Visual alerts
  • Tactile alerts

Deafblindess

Deafblindness is a combination of blindness and deafness. People who are deafblind encounter the same challenges as blind and deaf people would.

Digital Environments
Challenge Solution
Text or images
  • Screen reader with refreshable Braille output
Video and/or audio
  • Full transcript

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:

  • genetics
  • premature birth
  • illnesses
  • accidents
  • aging
Digital Environments
Challenge Solution
Mouse
  • Other input devices: keyboard, alternative keyboard, mouth stick, head wand, switch device,
    speech recognition, eye tracking
  • Developers and designers ensure keyboard (and other input devices) operability
Timed sessions
  • Designers can delay timeouts
  • Designers can provide alerts for timeout
  • Designers can allow time extension
Physical Environments
Challenge Solution
Steps and escalators
  • Ramps
  • Elevators
Small spaces
  • Wider spaces for wheelchair access
  • Remove obstacles in pathways
General
Challenge Solution
Walking
  • Walker
  • Cane
  • Crutches
  • Braces
  • Wheelchair
  • Scooter
Door knobs, handles, entrances
  • Door actuators
  • Motion sensors to automate door
  • Lever handles

Additional reading about motor disabilities:

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.