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Skip to 0 minutes and 6 secondsMIKE WALD: I'm Professor Mike Wald. And I work at the web and the internet science group in ECS at the University of Southampton. And I lead the accessibility team. Well, the difference between accessibility and usability can be quite subtle. Some people get them confused. And there is some disagreement about what is the overlap, but basically accessibility is about being able to use technology and for everybody to be able to use it. And it's also enforced, and supported, and backed up by legislation, whereas usability, in the past, had tended to mean can a particular person or a particular group of people use a particular piece of technology.

Skip to 1 minute and 2 secondsSo for example, a video player, if you needed your mouse to press the Play button to be able to start the video, but you couldn't access the Play button from the keyboard, then it would be usable with a mouse, but not accessible. Because somebody who couldn't use a mouse and could only use a keyboard wouldn't be able to play the video. There are lots of reasons why you might not be able to use a mouse. Physically, you might have a problem with controlling the mouse. You might actually be a blind user and actually not be able to see the Play button or the mouse cursor. So there are various groups of people.

Skip to 1 minute and 50 secondsAnother reason is you might not have a mouse, an actual touchpad might be not working on your computer. So there are lots of different reasons. But usability has been around for a long time, the concept of usability And people would say, can you design some technology for a particular target group? And it's only been more recently that legislation's come in and people have become more understanding about inclusive society and how it's important not to design things that exclude people. And so there is quite a big overlap between the two topics, but really for something to be properly usable, it should be accessible.

Skip to 2 minutes and 41 secondsAs another example, if you had a website and somewhere on one of the pages was the telephone number you had to contact for information or for help, if you were a sighted user, even if the website was terribly disorganised, you could scan the pages. And it wouldn't take you too long to spot the telephone number, the contact information. But if you were a blind user, you would have to have every word of every page read out to you by the screen reader, which reads in a computer voice. And it could take you hours and hours before you get to the telephone number. And so in that case, although, theoretically, the website's accessible, it's not really usable.

Skip to 3 minutes and 33 secondsBecause it's not an efficient way of getting the information.

Relationship between Usability, Accessibility, and User Experience

In this video Professor Mike Wald explains the issues that can arise with the various terms used when discussing digital technology services or products.

While users themselves might not care too much about the definitions of these terms, to ensure clarity in communication and discussion it is necessary to have a shared understanding and so these terms are discussed in this step with links to some definitions at the end of this step.

Defining the terminology

The term ‘Usability’ is normally used to refer to the actual use of the technology by a particular target group of users and contexts (e.g. including whether they find it easy to learn to use).

The term ‘Accessibility’ is normally used to refer to the use of the technology by everyone rather than just a specific group of users (e.g. including whether blind people can also use the technology).

The term ‘User Experience’ is normally used to refer to any experience of a user that is related to the use of that technology (e.g. including how they feel about the brand and whether they can get it easily repaired).

Only Accessibility has actual legislation …

While there have been many different guidelines produced for Usability, Accessibility and User Experience, only Accessibility has actual legislation making it illegal to disadvantage a disabled person through an inaccessible product or service. Some countries have general accessibility legislation while others have specific accessibility legislation for digital technologies.

Agreeing and enforcing any legislation is made more difficult by the overlapping nature of usability, accessibility and user experience that is illustrated in the Venn diagram which shows that user experience can encompass accessibility and usability while products and services need to be both accessible and usable.

A product or service that is theoretically accessible will not be used if for example it takes too long to achieve the user’s goal (e.g. a blind person in theory be able to find contact information on a website but if it takes them too long they will not persevere). There is no specific legislation for usability or user experience but there can be general legislation about a product or service being as described, of satisfactory quality and fit for purpose.

Intersection of Usability and Accessibility circles labeled usable and accessible and both usability and accessibility circles are contained in user experience circle

Figure 1 - Venn diagram showing relationship between User Experience, Usability and Accessibility.

The word ‘accessible’ is however also often used by people to refer to whether a technology is generally available (e.g. “The internet was not accessible from my hotel because they did not have wifi”). This can lead to confusion as there is no legislation requiring technology to be made available, only that there must not be discrimination against people with a disability.

There are many links related to this topic available from the bottom of this page.

How you would use the terms usability, accessibility, user experience? and what’s your experience of accessibility, usability and user experience?

Do you know what the Accessibility legislation is in your country ?

© This work is created by the University of Southampton and licensed under CC-BY 4.0 International Licence. Erasmus + MOOCs for Accessibility Partnership.

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This video is from the free online course:

Digital Accessibility: Enabling Participation in the Information Society

University of Southampton