ISO 9241 defines user experience as:

a person's perceptions and responses that result from the use and/or anticipated use of a product, system or service.

Based on this definition, we would expect that usability froms part of a user's experience when they set out to achieve a goal by accomplishing tasks using a product or service.

In the same document, human-centred quality is defined as:

usability, accessibility, user experience and reduced risk

So the question I would like to pose is this: If the purpose of applying a human centred design is to improve the user experience of a product or service, why is the definition of user experience more inclusive (i.e. includes usability) than the definition of human-centred quality (where usability is another element alongside user experience)?

  • Which version and part of ISO 9241 are you looking at? I'm assuming you are looking at Part 210 Human-centred Design for Interactive Systems (2010), and looking through the terms and definitions for this part I don't see a definition for human-centred quality?
    – SteveD
    Apr 10, 2017 at 14:08
  • @SteveD I was looking at a draft version of 9241-220 from around 2015, and even though I think the definition might have changed slightly in later versions (in 2016), both terms were included and in that version human-centred quality still separates usability and user experience.
    – Michael Lai
    Apr 11, 2017 at 11:07

4 Answers 4


Firstly, "Human Centred" and "Usability" are different things So now we need to define three terms.


Usability is simply the abstract concept of how easy it is to use a product or system. This could be framed in terms of general human usability, specific human usability (e.g. humans with specific accessibility issues), or even animal usability.

Human Centred

Human centred design is a specific branch of ergonomics that ensures that a product or system is designed to be easy to use for humans. This includes everything from making sure the graphics don't obscure the interface elements to making sure the interface is simple and easy to use.

User Experience

User Experience design is about nurturing a specific response in the user to meet specific business need. This can include making it easy to buy items to keep revenue up, or making it difficult to contact the company directly to keep call volumes down.

These are all very fine distinctions with (often) wide overlaps so can often be difficult to see where one ends and the next begins.

Of course, without speaking to the person/team/committee who designed the standard, we will never truly know why they made the distinction, but the differences detailed above would seem to offer a logical explanation.

  • But to design in a human centred way would involve catering for a good user experience, which means also making sure that there is an acceptable level of usability. The hierarchy seems to be Human Centred includes User Experience includes Usability doesn't it?
    – Michael Lai
    Apr 12, 2017 at 12:40
  • @MichaelLai Designing in a Human Centred way does not necessarily mean creating a good user experience: User Experience design takes business needs into account. If we look at an online retailer, human centred design would allow the users to select their products and get them delivered with as few interruptions as possible. User experience design takes into account that the user must pay for the products at some point and tries to make that as painless (and even delightful) as possible so the user, having parted with their money, still goes away with a good impression of the vendor. Apr 12, 2017 at 12:47
  • I think any type of design needs to take into account of the feasibility and constraints, whether it is done in a human centred way or a UX driven process. In this question I am purely interested in why usability and user experience seem to be elements on an equal hierarchy when it is in the context of human centred design.
    – Michael Lai
    Apr 12, 2017 at 13:07
  • The topic is about the ISO definitions whereas your answer is a somehow general understanding of the terms. But those arent correct answers regarding the ISO wordings and concepts. Might be good to have a look into the ISO's.
    – FrankL
    Apr 18, 2017 at 15:45

Some even argue that usability is seperate from User Experience. Perhaps this overview gives some insights into the answer you're looking for. enter image description here

  • 1
    What you will see from that diagram is the fact that a good user experience involves good usability, whereas it is very difficult to have a good user experience if it doesn't work well. So in a way it still makes the point that user experience design encompasses usability design. Of course, some would argue that Apple is an example where the brand and experience make some people focus less on the usability issues...
    – Michael Lai
    Apr 13, 2017 at 21:46
  • Interesting! You could say it's like a symbiotic relationship that needs each other to thrive? and +1 for the Apple example, I hope dazzling the user to make them forgive usability flaws never becomes a valid approach :')
    – Tom.K
    Apr 14, 2017 at 7:22

First to set right expectations: My answer is given based on the ISO standards.

Usability The current actual use of a software. It is observable and measurable. Has goals, tasks and paths. Usually it is measured regarding the three usability dimensions effective, efficient, satisfying.

User Experience Is the individual usage of a software. It even encompasses the expectations before and memories (experiences) of a former use. It is in a persons head, not observable, highly biased by eduction, experience, culture, capabilities, brand image and some more. It is usually measured indirectely by surveys. User Experience encompasses usability, the actual use, as out of this use one gets an experience.

Human-centred quality The term refers to ISO 27500 where the business objectives for a human-centred approach are written. Targets are board members. You geht a HC quality when you follow the human-centred design approach. Because it raises accessibility, usability as well as it reduces risks for workers, customers and risks of failing investment, no market acceptance. Think of HC quality is a sort of product quality for a working approach.

Human-centred design Is a set of methods, best practices and tools to accomplish a good usability and sets roots for a good user experience.

To answer your question: I think usability and ux is mentioned seperately just because it has two definitions in the ISO. It is a sort of linkage technique one finds often in the ISO texts.


Isn't Usability more of standards for user groups while user experience is more of a single user's perspective?

"Usability, when interpreted from the perspective of the users' personal goals, can include the kind of perceptual and emotional aspects typically associated with user experience. Usability criteria can be used to assess aspects of user experience"


So for ux, usability is inclusive while for human centered quality it is taken separately. For human centered quality should be measured/determined by both individual goals and goals of humans as a group perspectives.

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