Understanding the types of disabilities to build empathy

Accessibility is a vast topic that has a lot of misconceptions. When people hear the word “accessibility”, the first things that come to mind are colour blindness, assistive technology (screen readers), people with disabilities and minority.

Questions that usually come up

  • How many of our users are actually differently enabled?
  • Do we need to spend that much time, effort and energy on something that could be viewed as an edge case?
  • Are we focussing too much attention on a small group of people?

The thing is, not every disability is a visible disability and obvious. You can’t always tell that someone has a disability just by looking at them and not everyone will disclose that they have a non-visible disability. Disabilities can also be environmental or temporary.

Environmental disabilities

  • The lighting is poor or your computer monitor isn’t that great so you have trouble reading the screen.
  • You’re somewhere noisy so you can’t hear the video/audio very well phone support.

Temporary disabilities

  • Someone goes skiing and breaks their arm.
  • Your carpal tunnel is flaring up so you don’t want to use the mouse more than you have to.
  • You have arthritis in your hands (very common as people age).
  • Other temporary impairments could occur because of surgery or medication.

People who suffer from temporary impairments may not know about accessibility solutions. They may not know how to use accessibility features and will struggle to do their jobs if we don’t make our software accessible.

ACL’s accessibility goals

Here at ACL, we believe that building accessible software is the right thing to do for all of our users regardless of ability. Software that is designed and built to pass WCAG 2.0 accessibility standards results in a better experience for everyone. Out of a total of 38 requirements from WCAG 2.0 Level A and AA, there is only a very small numbers of the requirements pertaining to users with disabilities. The rest are related to usability.

Be inclusive

We want to design software that is accessible to as many people as possible.

Improve user efficiency

Accessible software allows users to navigate more effectively using a keyboard. (e.g. keyboard shortcuts or terminate an interaction flow using the esc key).

Colour blindness

Some people have reduced or lack sensitivity to certain colors (“color blindness”) or increased sensitivity to bright colors. These variations in perception of colors and brightness can be independent of the visual acuity.

The images below are just approximations of what someone with colour blindness would see. As colour blindness varies from person to person, a simulator cannot represent everyone’s vision.

Deuteranomaly (people who can’t see green, mild)

This affects 5% of males. Greens, yellows, oranges, reds, and browns may appear similar, especially in low light. It can also be difficult to tell the difference between blues and purples, or pinks and greys.

Normal vision
Normal vision

Deuteranopia (people who can’t see green, severe)

This affects 1% of males. Greens, yellows, oranges, reds, and browns may appear similar, especially in low light. It can also be difficult to tell the difference between blues and purples, or pinks and grays.

Normal vision
Normal vision

Protanomaly (people who can’t see red, mild)

This affects 1% of males. People with this have difficulty seeing red, orange and yellow. They have great difficulty distinguishing between oak and dark shades. They can confuse deep reds with blacks and dark greens and purples.

Normal vision
Normal vision

Protanopia (people who can’t see red, severe)

This affects 1% of males. They have difficulty seeing red, orange and yellow. Great difficulty distinguishing between oak and dark shades. Confuse deep reds with blacks and dark greens and purples.

Normal vision
Normal vision

Tritanomaly (people who can’t see blue, mild)

Extremely rare, only 5% of people who are colour blind have this. Confuses blue with green and yellow with violet.

Normal vision
Normal vision

Tritanopia (people who can’t see blue, severe)

Extremely rare, only 5% of people who are colour blind have this. Confuses blue with green and yellow with violet.

Normal vision
Normal vision

Incomplete Achromatopsia (limited colour)

Extremely rare. Incomplete or partial Achromatopsia compared to complete Achromatopsia may have better vision (20/120 to 20/80). The reduced vision could be compensated with low vision devices (http://www.achromatopsia.info/low-vision-care/).

Normal vision
Incomplete Achromatopsia
Normal vision
Incomplete Achromatopsia

Complete Achromatopsia (no colour)

Extremely rare. Complete Achromatopsia will have reduced vision (20/200 or less) due to an abnormality of the retina. They also have no color vision, sensitivity to light (photophobia) and the presence of nystagmus (shaking of the eyes). The reduced vision could be compensated with low vision devices (http://www.achromatopsia.info/low-vision-care/).

Normal vision
Complete Achromatopsia
Normal vision
Complete Achromatopsia

*Statistics referenced from:

Low vision/blind

Visual disabilities range from mild or moderate vision loss in one or both eyes (“low vision”) to substantial and uncorrectable vision loss in both eyes (“blindness”).

The term vision loss refers to individuals who reported that they have trouble seeing, even when wearing glasses or contact lenses, as well as to individuals who reported that they are blind or unable to see at all.


Substantial, uncorrectable loss of vision in both eyes.

Low vision (partial sight)


  • Includes poor acuity (vision that is not sharp)
  • Tunnel vision (seeing only the middle of the visual field)
  • Central field loss (seeing only the edges of the visual field)
  • Clouded vision.

Also solves for

  • Keyboard users who work faster with less reliance on using a mouse.
  • Users who are in less than ideal lighting situations or have lower contrast monitors.


  • Worldwide: 253 million
  • USA: 16.4 million people were between the ages of 18–64
  • Canada: 0.5 million with significant vision loss

*Statistics referenced from:

Examples of low vision

Example of central field loss
Example of peripheral field loss
Example of other field loss

*Images source from http://w3c.github.io/low-vision-a11y-tf/requirements.html#overview-of-low-vision

Hearing loss

Auditory disabilities range from mild or moderate hearing loss in one or both ears (“hard of hearing”) to substantial and uncorrectable hearing loss in both ears (“deafness”). Some people with auditory disabilities can hear sounds but sometimes not sufficiently enough to understand all speech, especially when there is background noise. This can include people using hearing aids.

Just a small minority of people needing hearing aids use them even though hearing aids can be vital for holding employment and improve quality of life.

Also solves for

  • Noisy Environments such as open offices or coffee shops.

Examples of hearing loss

  • Hard of hearing — mild or moderate hearing impairments in one or both ears
  • Deafness — substantial, uncorrectable impairment of hearing in both ears
  • Deaf-blindness — substantial, uncorrectable hearing and visual impairments


  • Worldwide: 5% of population (disabling)
  • Europe: 16% of adults (hard of hearing)
  • USA: 20% of the population (hard of hearing)
  • Canada: 10% of the population (hard of hearing)

*Statistics referenced from:

Cognitive and neurological

Cognitive and neurological disabilities may affect any part of the nervous system and impact how well people hear, move, see, speak, and understand information. Cognitive, learning and neurological disabilities do not necessarily affect the intelligence of a person.

Albert Einstein couldn’t read until he was nine. Walt Disney, General George Patton, and Vice President Nelson Rockefeller had trouble reading all their lives. Whoopi Goldberg and Charles Schwab and many others have learning disabilities which haven’t affected their ultimate success.

People with learning disabilities are as smart or smarter than their peers. But they may have difficulty reading, writing, spelling, reasoning, recalling and/or organizing information. A learning disability can’t be cured or fixed; it is a lifelong issue.

Learning disabilities

  • Reading (dyslexia)
  • Writing (dysgraphia)
  • Processing numbers (dyscalculia)
  • Spatial or temporal orientation

Fifteen percent of the U.S. population, or one in seven Americans, has some type of learning disability, according to the National Institutes of Health.

Also solves for making the user interface more intuitive

  • Simplify complicated layouts.
  • Allow users to self-enable with new features (more tooltips or guided tours).
  • Break complex sentences into smaller, easier to read pieces.
  • Help users understand where they are, where they want to go and how to get there.


Spatial or temporal orientation / worldwide population: unknown
Spatial orientation disability- difficulty controlling their body. May not always know where arms and legs are without looking.(Difficulty switching from keyboard to mouse?)

Temporal orientation is a cognitive structure for processing information by comparing events in relationship to when they occur. This involves the critical skill of telling time and much more. It is essential for planning, organizing, communicating, and record keeping.

Reading (dyslexia) / worldwide population: approximately 15%
Characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities.

Writing (dysgraphia) / worldwide population: unknown
The inability to handwrite coherently. Can be compensated with touch typing(keyboard). There are not many studies about dysgraphia, so the prevalence of this learning disability is unknown.

Processing numbers (dyscalculia) / worldwide population: 3% to 6%
Adults with this math-related condition will find it difficult to keep track of numbers, perform simple calculations, and memorize basic math facts.

*Statistics referenced from:

Motion and vision Sensitivities

Photo-epileptic Seizures (Photo Epilepsy) are caused by strobing, flickering or flashing effects and is more of an extreme reaction to what people see on the screen. A much more common disorder that many people might not even realize they have is vestibular disorder.

Vestibular disorders

Even if an animating or moving object does not cause a seizure, it may cause nausea or dizziness in some people. Vestibular Disorders are caused by parts of the inner ear and brain that process the sensory information involved with controlling balance and eye movements.

  • 35% of adults aged 40+ in the USA have experienced some form of vestibular dysfunction.
  • After age 55 the rate of new cases start to increase as people develop strokes, brain tumors, or Alzheimer’s.
  • Flashing or patterned effects can make people with or without epilepsy feel disorientated, uncomfortable or unwell.

The following items can result in difficulties for users with vestibular disorders:

  • High contrast graphics with tight parallel lines.
  • Animated scrolling that lasts longer than perhaps 1/4 second.
  • Parallax or reverse parallax — simultaneous foreground and background scrolling in different directions or at different speeds.
  • Moving images beneath static text.


  • As many as 35% of adults aged 40 years or older in the United States — approximately 69 million Americans — have experienced some form of vestibular dysfunction.

*Statistics referenced from:

Speech disabilities


  • Difficulty producing speech that is recognizable by other people or voice recognition software.
  • Loudness or clarity of someone’s voice

US statistics

  • Estimated 17.9 million adults 18+ (7.6%) reported having a problem with their voice in the past 12 months.
  • 9.4 million (4%) of adults reported having problems using their voice that lasted 1+ weeks during the past 12 months
  • More than 70 million people worldwide stutter (1 in every 100).
  • More than 3 million Americans (1%) stutter.

How can we make their life easier?

By providing alternatives to phone/voice chat support such as live chat and email.

Also solves for

  • Loud environments
  • Poor/unstable Internet connection that is unable to support voice chat.

*Statistics referenced from:

Learn to build accessible software

Now that you’re empathy is all built up, you should read, “Learning to build accessible software at ACL”. In it I share out the 4 hour course I developed for our teams.