I’ve seen people use the terms “usability” and “accessibility” interchangeably, often surfacing in discussions about user experience. However, these concepts, while related, are not interchangeable. Understanding the nuanced differences between them is essential for any product designer aiming to create truly inclusive products. Here’s a breakdown to clarify these often-confused terms:
Usability
Usability refers to how efficiently, effectively, and satisfactorily a user can use a product to achieve their goals. It’s about the ease of use – how intuitive the interface is, how quickly users can learn to navigate it, and how well the design aids in accomplishing tasks. Key aspects include:
- Learnability: How easy is it for new users to start using the product?
- Efficiency: Once users have learned the design, how quickly can they perform tasks?
- Memorability: When users return to the design after a period of not using it, how easily can they re-establish proficiency?
- Errors: How many errors do users make, how severe are these errors, and how easily can they recover from them?
- Satisfaction: How pleasant is it to use the design?
Usability focuses on the majority of users, assuming a standard level of ability — those without disabilities or under typical conditions.
Accessibility
Accessibility, on the other hand, deals with designing products that can be used by people with a wide range of abilities, including those with disabilities. It ensures that products are usable by everyone, regardless of sensory, motor, or cognitive impairments. Key considerations include:
- Perceivability: Information and user interface components must be presentable to users in ways they can perceive. This includes options for screen readers, alternative text for images, and sufficient contrast between text and background.
- Operability: The interface must be operable by everyone, including those who cannot use a mouse or see the screen. This means providing keyboard navigability, enough time for users to read and use content, and avoiding content that could cause seizures.
- Understandability: The design should be clear and understandable, with language that’s simple, instructions that are predictable, and error messages that are helpful.
- Robustness: Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.
If you are designing an accessible interface, have a look at the Gov UK accessibility requirements and guidelines. They are a great resource for
Why the Distinction Matters
While both usability and accessibility aim to enhance user experience, they target different aspects:
- Overlapping Goals: Both aim for an effective user interaction but from different angles. Usability ensures that the interaction is efficient for the ‘average’ user, while accessibility makes sure that interaction is possible for all users.
- Design Implications: For usability, you might focus on simplifying workflows or optimizing user journeys. For accessibility, you might need to add features like voice commands, closed captions, or alternative navigation methods.
- Compliance and Ethics: Accessibility often has legal implications, with standards like WCAG (Web Content Accessibility Guidelines) providing benchmarks for compliance. Usability, while not legally mandated, is crucial for market success and user retention.
For product designers, understanding that usability is about ease of use for the general population, while accessibility ensures inclusivity for all, is fundamental. By integrating both principles into your design process, you not only create products that are easier to use but also ones that are accessible to everyone, thereby broadening your product’s reach and impact. Remember, a product can be usable but not accessible, or accessible but not particularly user-friendly in terms of efficiency or satisfaction. The goal is to achieve excellence in both for a truly inclusive design.