Usability vs. user experience

5 min read · BoK 2F.2· p. 45–46

Learning objectives (3)

Differentiate usability from user experience
Name the core areas of UX (useful, usable, desirable, findable, accessible, credible, valuable)
Explain how accessibility fits within the broader UX framework

Why it matters

Usability and user experience are frequently used interchangeably, but they describe different scopes of concern. For CPACC, understanding the distinction — and where accessibility fits within the broader UX framework — matters for advising organizations on how to position and scope their accessibility work. (BoK p. 45)

Usability

Usability is the quality of a product in terms of how well specific users achieve specific goals in a specific context. The ISO 9241-11 definition organizes usability around three measurable dimensions: (BoK p. 45)

Effectiveness: the accuracy and completeness with which users achieve specified goals.
Efficiency: the resources expended in relation to the accuracy and completeness of goals achieved — typically measured as time on task.
Satisfaction: freedom from discomfort and positive attitudes toward the use of a product.

Usability is evaluated in context — the same product may be highly usable for expert users and poorly usable for novice users. Jakob Nielsen identified five additional usability quality components in common use: learnability (ease of first use), efficiency (expert speed), memorability (ease of returning after a gap), errors (frequency and severity of mistakes), and satisfaction.

User experience

User experience (UX) is a broader concept than usability. It encompasses the totality of a person’s perceptions, responses, and attitudes when using — and reflecting on using — a product, system, or service. UX includes usability but extends to the emotional, aesthetic, and social dimensions of use. (BoK p. 46)

Peter Morville’s UX Honeycomb identifies seven quality attributes of a good user experience:

Attribute	Description
Useful	The product serves a genuine need
Usable	The product is easy and efficient to use
Desirable	The product is emotionally and aesthetically appealing
Findable	Users can find the product and its content
Accessible	People with disabilities can use the product
Credible	Users trust the organization and content
Valuable	The product delivers value to users and the organization

Where accessibility fits

In Morville’s framework, accessibility is one of the seven UX attributes — alongside usability, desirability, and credibility. This positioning matters: accessibility is not a subset of usability, and usability is not a subset of accessibility. They are distinct, parallel concerns within the broader UX goal. (BoK p. 46)

A product can be accessible but have poor overall UX (technically usable by people with disabilities but emotionally unsatisfying or untrustworthy). A product can have excellent UX for non-disabled users but be entirely inaccessible. The UX framework integrates accessibility as a required attribute of a good product — not an optional add-on.

Real-world example

A mobile banking app is evaluated from both usability and UX perspectives. Usability testing shows that users can complete transactions in under two minutes with few errors — high effectiveness and efficiency. However, UX research reveals: users find the visual design cold and institutional (low desirability), they do not trust the security indicators (low credibility), and users who are blind report the app is inaccessible to their screen readers (low accessibility attribute). The app scores high on usability but fails on broader UX dimensions — including the accessibility dimension that disability law requires.

Key terms

Usability: The effectiveness, efficiency, and satisfaction with which specific users achieve goals in a specific context; a component of user experience. (BoK p. 45)
User experience: The totality of perceptions, emotions, and attitudes a person has when interacting with a product — broader than task completion or usability. (BoK p. 46)
Learnability: The ease with which new users can accomplish basic tasks the first time they encounter a design; a dimension of usability. (BoK p. 45)
Desirability: A UX quality attribute addressing the emotional and aesthetic appeal of a product — whether users want to use it, beyond whether they can. (BoK p. 46)
Useful: A UX quality attribute describing whether a product fulfills a genuine need for users; one of Morville's seven UX Honeycomb attributes. (BoK p. 46)
Credibility: A UX quality attribute addressing users' trust in the accuracy, honesty, and reliability of a product and the organization behind it. (BoK p. 46)

Check yourself

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According to Peter Morville's UX Honeycomb, which of the following is one of the seven core UX quality attributes?

a) Perceivable
b) Equitable
c) Desirable — correct answer
d) Operable

Explanation: Morville's UX Honeycomb identifies seven quality attributes: useful, usable, desirable, findable, accessible, credible, and valuable. Desirable addresses the emotional and aesthetic appeal of a product — whether users want to use it, not just whether they can. This goes beyond usability (can users complete tasks efficiently?) to the full user experience.

A banking app allows users to complete transactions quickly with few errors. User satisfaction surveys reveal that users feel anxious using the app, distrust that their data is secure, and describe the visual design as cold and off-putting. Which UX quality attributes are failing?

a) Usability is failing — anxiety and distrust indicate the app is not effective or efficient
b) Desirability and credibility are failing — users find the app unappealing and untrustworthy despite completing tasks efficiently — correct answer
c) Accessibility is failing — anxiety and distrust indicate the app is not accessible to users with anxiety disorders
d) Findability is failing — users cannot locate the transaction features they need

Explanation: This scenario illustrates the distinction between usability (task completion: effective and efficient) and user experience (the full picture: also desirable, credible, and trustworthy). High usability scores do not guarantee a good UX. Desirability (emotional/aesthetic appeal) and credibility (trust in the organization and data practices) are the failing UX attributes.

How does accessibility relate to usability and to user experience according to the UX Honeycomb model?

a) Accessibility is a subset of usability — it is the aspect of usability that applies to users with disabilities
b) Usability is a subset of accessibility — all usability improvements are inherently accessibility improvements
c) Accessibility and usability are both distinct components of UX — neither contains the other; both are required for a complete user experience — correct answer
d) User experience is a subset of accessibility — all UX work is accessibility work because it improves the experience for disabled users

Explanation: In Morville's UX Honeycomb, both accessible and usable are distinct, parallel attributes of user experience. A product can be usable (effective, efficient task completion) but inaccessible (screen reader incompatible). A product can be technically accessible but have poor UX (accessible but undesirable, uncredible). Full UX requires all seven attributes, including both accessible and usable.

Sources

BoK references

Section 2F.2 — IAAP CPACC Body of Knowledge v4.0 (Oct 2023), p. 45–46