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Types of Disabilities

Lesson 1 of Section 1


What comes to your mind when you think about accessibility? In terms of web accessibility, most would consider blindness as the largest factor of being unable to use the Internet since it's widely regarded as a visual media. However, advancements in today's Internet and service providers allow for much richer content on several aspects, including visual, audio, and interactive media.

The Ontario government defines accessibility as simply giving people of all abilities opportunities to participate fully in everyday life.

That is why it is important for you to understand all the types of impairments that exist, so that you can deploy content that is perceivable by all!

Visual Disabilities

This is the most obvious disability that exists for web accessibility. Blindness can range from mild to complete, and variations exist such as:

  • Regular blindness: Simply not being able to see as well as regular-sighted people. While some blind users may be able to still walk on their own with ease, the task of reading a screen, while it may be possible, is very time-consuming for them, which means they utilize special tools to help them go faster, such as a screen reader.
  • Colour blindness: This is the lack of being able to perceive particular colours or pigmentation. Your user will see images in completely different colours that you are used to, and there is high possibility that a user might miss content completely if there is minor colour variation. Below is an example of a photograph perceived by colour blind users in comparison with the original. You can see between each sample photo that certain colours are completely missing! The leaves go from green to light brown, and the bright magenta of the flower changes to grey, red, and even blue for some users! (Source)
    images as perceived by a protan, deutan, and tritan colour blind users, with variations in colour among different disabilities
  • Low vision: This is a disability that cannot be corrected with glasses. A few examples of low vision-type disabilities are macular degeneration, glaucoma, diabetic retinopathy, and cataract.

    a sample of text with a dark spot in the middle, showing the effect of macular degeneration
    Macular Degeneration

    a sample of text with no visibility on the outer edges and a blurry centre, showing the effect of glaucoma

    a sample of text with blurry or distorted spots, showing the effect of diabetic retinopathy
    Diabetic Retinopathy

    a sample of text that appears to fade into the background

Auditory Disabilities

Even though this disability is simple to accomodate in terms of web accessibility, most people do not consider deafness as a factor when designing a web page. However, with the increase in multimedia content being made available over the Internet, it is becoming much more important to provide alternatives to auditory content. You will have to consider this disability if you plan on creating lectures, YouTube videos, or other types of multimedia with auditory content.

There are variations of hearing loss as well as severity. The variations are:

  • Conductive hearing loss: damage or blockage of the internal parts of the ear, specifically the parts designed to be able to vibrate in response to receiving sounds.
  • Neural hearing loss: when the hair cells or auditory nerve is damaged, which prevents the auditory signal from actually reaching the brain.
  • High tone hearing loss: inability to hear high pitched tones, such as women's voices.
  • Low tone hearing loss: inability to hear low pitched tones, such as men's voices.

Since hearing loss can range from mild to complete, you should bear in mind that some users may not require assistance if you're creating auditory content with clear pronounciation and minimal background noise. This is no accessibility requirement, but can serve as a useful tip for going above and beyond the minimal specifications!

Motor Disabilities

Have you ever tried to navigate a drop-down menu that had multiple levels, but had to start back from the beginning because you accidentally hovered your mouse outside of the menu? Users with motor disabilities (such as Parkinson's disease) have to deal with this problem all the time, and it is up to web developers and designers to create a user interface that takes this disability into account. You can test the McMaster Menu for yourself: see how long it takes before the menu disappears after you hover the mouse outside of the menu. This design was on purpose and allows for easier usage of the McMaster University website.

The motor impairments that exist may be a lack of ability to move a mouse (requiring the sole use of a keyboard), lack of control of the mouse and/or keyboard (requiring the use of error-checking), and may have to use voice-activated or "puff-and-sip" technology to control a computer.

Cognitive Disabilities

There is a vast number of cognitive disabilities that exist to actually go through them one by one, but they can mostly be summed into six different categories of difficulty:

  1. Memory
  2. Problem-solving
  3. Attention
  4. Reading, linguistic, and verbal comprehension
  5. Math comprehension
  6. Visual comprehension

It is your job to ensure that content can be created to help users cope with these deficiencies on their own.


Most people know that epilepsy is a condition that causes people to have seizures under certain circumstances. It is up to you to ensure that content that you publish does not contain seizure-inducing material. An additional step to help with epilepsy is to avoid "optical illusions," where the image appears to be moving but is actually not.

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