There are many different groups of people with disabilities, and one key fact deserves attention right away: not all disabilities are present from birth. Some are acquired through accidents or illness later in life, and every disability exists on a spectrum of severity. As a principle, we design for accessibility across as many disability types and severity levels as possible — the goal is to reach as many people as we can, without discriminating based on the nature of their condition.
Blindness and Web Accessibility
This is the most well-known and widely discussed group in the accessibility world. Most people, when they think about web accessibility, think of blind users — and understandably so, since blind users are often the most vocal community online. That said, web accessibility is not synonymous with screen reader compatibility alone. If you read many accessibility discussions, you need to be careful not to fall into the trap of equating web accessibility exclusively with blindness.
Blind users rely on screen readers — software that reads the screen aloud. Some people assume that "if it works with a screen reader, it's accessible." That's only partially true. It's a bit like saying, "doing X will always produce
Y — just do it this way and it'll work." In an ideal world, yes, that might hold true. But in the real world, you also need to consider the browser, its support for various features, the user's interaction method, whether they have low vision or are a deaf user, and so on.
There are other factors to consider for users who rely on sequential input devices — for example, switch controls ( SWITCH buttons).
Blind users navigating with a screen reader may have no trouble interacting with an application or page content, but someone with limited mobility may find that process extremely difficult. Users with motor impairments will often find that even tabbing through a webpage tabbing can be exhausting. Suddenly, those 20 links you thought were a great idea to include don't look so great anymore.
So try not to think only about blind users (though they are, of course, extremely important) and screen readers when you approach accessibility. That said, since screen reader technology is highly sophisticated, designing with both in mind serves all users well.
Physical Disabilities
There are many types of physical disabilities that can manifest in a wide range of ways, from mild to severe. Physical disabilities can be congenital or acquired later in life as the result of an accident.
Common challenges include loss of physical control over movement or involuntary muscle contractions, such as tremors. People with physical disabilities often become fatigued by even simple actions.
When it comes to using a computer, people with physical disabilities frequently cannot use a mouse.
Various assistive tools are available, such as: switch controls, joysticks, and other input devices. It's great that technology exists to help people communicate with computers. However, some people with physical disabilities cannot use any type of AT (assistive technology). Things can become very difficult — or even impossible — if the applications they want to use, such as media players, image viewers, calendar tools, and of course websites, lack accessibility settings. One of the most important examples is keyboard support. Applications that don't support accessible keyboard navigation are, in effect, unusable without a mouse.
Building websites with full keyboard accessibility is probably one of the most impactful things you can do for users with physical disabilities. Make it a golden rule — keyboard accessibility. It's a great principle that will also support switch users and other sequential input devices. As a bonus, it broadens your user base and raises the overall quality of your product.
Users with Cognitive and Sensory Disabilities
This covers a broad spectrum of disabilities affecting reasoning, quantitative perception, learning ability, and memory.
People with cognitive or sensory disabilities are arguably the most challenging audience to design for. This is largely because it's a relatively new area of research, and the evidence base for which solutions work, don't work, or only partially work is still developing. Web development techniques and guidelines related to cognitive accessibility exist, but they are limited and much work remains. That said, understanding of cognitive and sensory disabilities is steadily improving over time, and accessible development practices are evolving to meet the needs of this group.
Some of the challenges designers face when building interfaces usable by people with cognitive and sensory disabilities are outlined in the sections below.
Perception
This refers to visual and auditory difficulties where certain shapes, forms, and sounds can be hard to recognize. Understanding how to serve users with perceptual difficulties can be challenging, because it's hard to know how well they can perceive certain interface elements. Care should be taken with the combination of visual and auditory cues used in rich media
interfaces, as these can cause issues such as disrupted page flow. Consistent, clear design can definitely help — components with obvious functionality, combined with visual cues and a clean layout.
Memory and Attention
Problems with short-term memory and attention can have a profound impact on a person's ability to complete even basic tasks, and the challenge of getting them to use more complex technologies is considerable.
People with memory loss issues may find themselves completely lost when trying to understand and respond to something as routine as filling out a contact form, or correcting an error in the expected way.
Sequencing
Sequencing refers to the ability to connect auditory and visual cues over time, or to understand what steps are required to complete a given task. Difficulties with sequencing can be reduced by providing cues within the interface — for example, helping users understand when input is required. Sequencing-related issues can also be minimized by avoiding unnecessary use of flashing content, animation, or movement that can distract the user and pull their attention away from the core functionality — and honestly, I'd argue this bothers most users, not just those with disabilities.
Dyslexia
The term dyslexia covers a wide range of conditions related to difficulty interpreting words, numbers, or mathematical information. Using clear, concise language for web content can be a significant help for people with dyslexia, as can using the right typeface. If, for example, you use a Serif font, people with dyslexia often struggle with letters that include serifs or tails, which in many cases leads to confusion about the message or the task at hand.
People with dyslexia often rely on visual cues to help them distinguish one letter from another. You can find some general font tips at Dyslexic.com, in particular www.dyslexic.com/fonts.
A note on fonts: Comic Sans is actually considered a readable choice for dyslexic users, though most designers would sooner give up their coffee than use it.
A designer-friendly font created specifically for dyslexic readers is Dyslexie. The typeface was developed at the University of Twente in the Netherlands to help people with dyslexia read more easily. It's based on the observation that many of the 26 letters in the standard Latin alphabet — as used in English — look very similar to one another, such as v/w, i /l or n /m. As a result, people with dyslexia frequently confuse these letters. By redesigning these characters to emphasize their differences, Dyslexie has been shown to reduce the number of reading errors people with dyslexia make.
Deaf and Hard-of-Hearing Users
At first glance, this group may seem to have the easiest time browsing the web compared to other disability groups. But consider this important fact: approximately 35% of all internet traffic comes from video content — and that share keeps growing. Through video channels, people can learn virtually anything: courses on every hobby imaginable, professional training, news, and entertainment series. When you think about it, if we don't make video content accessible (and not only for this group!), deaf and hard-of-hearing users simply won't be able to benefit from it — and they'll be left behind.