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Usability Principles

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What is it?

18 industry-standard usability principles used to formally evaluate the usability of systems, applications, and interfaces.

Why does it matter?

Consistent principles allow us to better align to improved standards for user experience. 

When would you use these?

The usability principles are useful during the design phase, and during evaluation of designs or production interfaces. By adhering to these principles, you will ensure that your experience will meet usability standards. Having an expert user experience designer conduct a usability review of your interface, you can identify usability issues before rolling it out to users, or to add to your enhancements backlog.

What is included?

Below are the usability principles we use to evaluate systems, applications, and interfaces.

  Principle Description Examples

1

User Control

The interface will allow the user to perceive that they are in control and will allow appropriate control.


Let the user choose when to advance to next page, instead of automatically redirecting them.

2

Recognition vs. Recall

Reduce short-term memory load by assisting user and providing needed information through the interface

  • If asking a user for their account number, provide it for them if possible.

  • If user is filling out multi-page form, show the information they have already submitted when asking for confirmation.

3

Mental Model

Interface/system should match mental models that the user holds of the real world.

  • If a person was looking for rooms in multiple buildings, show rooms grouped by building, not in an alphabetical list.

4

Clarity

The interface will communicate as efficiently as possible.

  • Instead of a button saying "Click here to submit your form," just use "Submit."

5

Aesthetic Integrity

The interface will have an attractive and appropriate design.

  • Interface styles support the user focusing on the actions they are completing, not distracting them.

6

Simplicity


The interface will present elements simply.

  • Instead of adding extra styles, graphics, words, and lots of functionality, reduce the complexity on the page and simplify down to the essential information/elements.

7

Predictability


The interface will behave in a manner such that users can accurately predict what will happen next.

  • Instead of having a button that says "Go!" provide a "Submit form" button with text telling the user what will happen next.

  • Action button on multi-step form could say "Complete order and proceed to shipping details.

8

Interpretation

The interface will make reasonable guesses about what the user is trying to do.

Chrome autofill will fill out a form based on a user's contact information that it knows.

9

Accuracy

The interface will be free from errors.

Form will not allow characters submitted that will break the form.

10

Error Handling & Prevention

The system will prevent errors as much as possible, and provide simple error handling in meaningful terms

  • Validation on form fields to prevent user error

  • Helpful instructions in context of the interface to assist the user

  • Plain language in the user's terms to explain errors.

11

Customization

Allow users to customize the UI as appropriate. 

  • ServiceNow dashboards let you customize what you see.

  • Options for user to choose settings between list view and grid view of items.

12

Shortcuts

Enable frequent users to use shortcuts for common tasks

  • Showing "recently viewed" items to the user.

  • "Quick links" menu to frequent actions.

13

Consistency

Strive for consistency across the interface and system.

  • Interface uses same names for menu items as their corresponding page titles.

  • Logo is always in top left, and search is always in top right and does not change on different pages of the interface.

14

User Support

The interface will provide additional assistance as needed or requested.

  • Contextual help provided through information links to explain form fields and why they are needed.

  • A permanent link to customer support in the interface.

15

Precision

The interface will allow the user to perform a task exactly.

  • Ensure users can complete tasks efficiently, and not have to rely on work-arounds or repetitive processes.

16

Forgiveness

The system will permit easy reversal of actions.

  •  If user mistypes their email address and misses the "@," the form should validate the field and alert the user to the error so they can fix it.

  • If user submits the form, let the user edit the form.

  • Provide an "undo" button when editing.

  • Revision history

17

Feedback

The interface will offer informative feedback to the user.

  • Confirmation message upon action completed, confirming to the user that it was a success.

  • If user has not filled out a required field, highlight the field in red and have text saying "This field is required."

18

Accessibility Compliant

The interface will meet AA WCAG level 2 accessibility compliance

  • All links should have accessible active/focus/hover states.

  • All interfaces should be navigable by tabbing (keyboard only).

  • All images have alt-text labels

Going further

If you are interested in learning more about these principles, or having us conduct an expert usability review, please get in touch.

Contact us