Accessibility, Usability, and the Importance of Both

4 July 2023 - Demelza Feltham

Accessible entry sign

When performing accessibility work for clients, I see many overlaps with usability heuristics. In other words, there is an issue that will not only limit the experiences of a user with a disability but will also pose an issue for a user with no additional access requirements. To more formally examine this, I am going to review a systematic standard of each discipline; the Web Content Accessibility Guidelines (WCAG) and a selection of usability heuristics authored by Jakob Nielsen and Steve Krug (for the purpose of this article, I am limiting the heuristics to six, although there are significantly more usability heuristics out there in the ether). Although addressing the usability of a site alone will not ensure digital products and services are completely accessible, there is something to be said for accessible products and services contributing to the usability for everyone. The same can be said for addressing the accessibility of a site alone, you might tick the guidelines and avoid any legal ramifications, but without analysing the usability of the site/product, you might end up with a very poor user experience, regardless of its WCAG compliance.

Usability heuristics act as archetypes for best practice when it comes to user interfaces in helping to determine the usability of a design or product. Similarly, the WCAG guidelines are used to systematically determine the accessibility of a product. Both aid in providing a standard. However, WCAG is an internationally recognised standard of guidelines that adheres to legislation, whereas heuristics are not codified as strictly as WCAG. Despite the crossover, the intent of this article is not to achieve a one-to-one mapping of WCAG guidelines to usability heuristics. Rather it is to recognise the importance of both approaches and the similarities they bear. Accessibility and usability are both essential components of a good user experience. To focus only on one would significantly detract from the quality of the other.

Visibility of System Status(this will open in a new window)

This heuristic is varied in application, but ultimately, it is about transparency between the system and the user. Does the user know where they are in their journey? Is it clear the system has registered the users request? Is there visible feedback to suggest so? This heuristic ‘encourages open and continuous communication, which is fundamental to all relationships’, noncompliance with this heuristic would look like a user that is ‘uninformed about the system’s current status’ and therefore, ‘cannot decide what to do next to accomplish their goals’ (Harley, NN Group 2018).

Guideline 4.1.3, Status Messages(this will open in a new window), requires that users be made aware ‘of important changes in content’ that is ‘not given focus’ (W3C). Compliance with this guideline means that individuals using assistive technology are made aware of any changes in the same way other users are made aware. It may be that there is change to a screen’s status that is communicated visually, however, nothing is announced to screen reader users to make them aware of this change. Blind and low-vision users need to be informed of changes that happen on the screen via a screen reader since they would not be able to perceive these updates being visually presented. Failing to ensure this would cause users to be unaware of such changes. As is the case with this heuristic, the status of the system must be communicated to the user.

Match between system and real world(this will open in a new window)

Too often the text used on a website can be confusing for users. Use language that is familiar to your users and avoid using terminology or jargon that will alienate them. There are a few instances where the WCAG guidelines mirror the sentiment of this heuristic, albeit with a little more technicality.

Abbreviations should be accompanied by ‘a mechanism for identifying the expanded form or meaning of abbreviations’ (W3C) according to guidelines 3.1.4, Abbreviations(this will open in a new window). Furthermore, the use of jargon and/or complex words, can make it difficult for all individuals, and especially those with cognitive impairments. Compliance with 3.1.3, Unusual Words(this will open in a new window), is consistent with this heuristic in its omittance of copy that alienates and confuses the user.

Consistency across systems(this will open in a new window)

This heuristic states that maintaining consistency increases learnability and reduces confusion. Consistency creates a cohesiveness for users that contributes to the trust and ease with which users navigate websites, whereas an inconsistency in the look and function of an interface can be problematic for all users, particularly those with cognitive impairments, low vision and users that are blind.

Consistency is the bedrock of mental models. Users form mental models through convention. These conventions are reiterated through consistency. It is important to leverage this consistency from a heuristic perspective and an accessibility perspective. There are a couple of WCAG guidelines that echo this heuristic. Compliance with 3.2.3, Consistent Navigation(this will open in a new window), requires websites to adopt consistency when it comes to the presentation and the layout of a website. Consistent navigation ‘helps users become comfortable that they will be able to predict where they can find things on each page’ (W3C) which helps users with cognitive and visual impairments.

Guideline 3.2.4, Consistent Identification(this will open in a new window), requires that consistency must also apply to functional components in the page. When elements repeat throughout a site it is important that users can leverage that repetition and build familiarity with the look and function of the elements. You can imagine the confusion for users if there are components that have the same functionality but are styled differently. This frustration escalates to a significant problem for users with cognitive impairments, increasing the cognitive load, ‘if identical functions have different labels (or, more generally, a different accessible name) on different Web pages, the site will be considerably more difficult to use’ therefore ‘consistent labeling will help’ (W3C).

Recognition rather than recall(this will open in a new window)

This heuristic is based on the ‘the distinction between two types of memory retrieval: recognition versus recall’ (Budiu, NN Group, 2014). To limit the cognitive load of a user, according to this heuristic, the usability of a site improves when information is present on the interface and a user can recognise it, as opposed to have to recall it with minimal cues. An example of needing to recall information is when logging into a site, ‘you have to remember both a username (or email) and a password. You receive very few cues to help you with that memory retrieval’ (Budiu, NN Group, 2014).

Recalling this information can be particularly problematic for people with cognitive disabilities, let alone a broad usability issue for a wider audience. The current working draft of WCAG 2.2 which at the time of writing this article, is yet to be published, contains 3.3.8, Accessible Authentication(this will open in a new window), which is a newly proposed guideline, that seeks to remedy aspects of non-compliance with this heuristic. 3.3.8 provides an alternative way to authenticate that doesn’t require a cognitive test. For example, authenticating a device using a face scan.

Help and Documentation(this will open in a new window)

Everyone benefits from a little help now and then. Providing help and documentation throughout the user journey improves the usability of a site. This heuristic suggests there are two types of help, the first being proactive help, which as it suggests is to prevent problems occurring. Designers should ‘anticipate when your users will need help and provide relevant information that will support them in accomplishing their goal’ (Joyce, NN Group, 2020). Proactive help shares the same approach as guideline 3.3.2, Labels or Instructions(this will open in a new window), which means that instructions are provided before they are required to avoid user error.

The second type of help this heuristic refers to is reactive help. The help and documentation offered should be digestible and readable. An update in the proposed WCAG 2.2 includes a new success criteria, 3.2.6, Consistent Help(this will open in a new window). Compliance with this proposed guideline ensures that users can always find help easily on a website and that there must be at least one form of help included on each page, thus improving the accessibility and usability of the site.

Don’t waste my time(this will open in a new window)

This next heuristic is one of Steve Krug’s, a senior usability expert. Ultimately, it is good manners. Respect your users time and avoid wasting it. Time is an entity preserved in a new addition to WCAG 2.2, which is 3.3.7, Redundant Entry.(this will open in a new window) Although it doesn’t speak directly to preserving time, compliance with it does seek to hold off any mental fatigue caused by needing to duplicate information and hence, increase the journey time.

Often forms require users to enter the same information more than once, for example, a billing address and a shipping address can often be populated with the same address. This can be an accessibility issue for users with a cognitive impairment, ‘users with learning, and cognitive disabilities are highly susceptible to mental fatigue’ and as far as usability, not only does this increase the journey time for users, it also contributes to the ‘natural gradual mental fatigue’ which can be ‘accelerated by the stress of recalling information from short-term working memory’ (W3C).


In summary, identifying the crossover between these two approaches is a strength, but equally, identifying their departure from one another is also a strength. Most recently, User Vision conducted a round of usability testing with people with disabilities after conducting an accessibility audit on the same site. The usability testing captured further issues that were not found in the audit thus reiterating the importance of usability testing. There is no proxy for testing with people and applying both approaches is important for ensuring a quality user experience.

“For most of us, technology makes things easier. For a person with a disability, it makes things possible.” - Judy Heumann, American Disability Rights Activist and Former US Assistant Secretary.

There are of course, more serious implications for an inaccessible site than there are for a site with poor usability, however, the issue with focusing solely on accessibility is that it can become a tick box exercise to avoid legal ramifications. Neither approach exists in a vacuum, and if the goal is a usable site that is accessible for everyone, then it is important to employ both approaches. It is important to note that heuristics are, by their nature, ‘broad rules of thumb’ and are ‘not specific guidelines’ (Nielsen, 2020), however, the guidelines are granular by nature. So, despite their crossover, their application looks very different.

Whether your business is looking to be WCAG compliant, conduct a round of usability testing with users and/or people with disabilities, develop a personalised, robust UX strategy, or any other one of our services, send us an email - we’d love to help!

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