3.2 Predictable

Make web pages appear and operate in predictable ways.


Consistency makes everything easier to understand. For example, you already know a link is underlined, so if you don't see an underline, you don't expect it to be a link. If you do see an underline, you do expect it to be a link. On the other end, if expectations and results are not the same, like underlined text without a link, you create confusion.

Important ideas to consider regarding predictability and consistency:

  1. Give them power of choice: Most assistive technologies need to access a certain component before someone decides whether or not to interact with it. If your cursor or focus is on a component, and it does something before that assistive technology could warn them, then they become lost or confused.
    1. Example: If you have main navigation that takes you to a page automatically when hovering your mouse over the link, you will have a lot of unintentional page changes and frustrated users.
    2. Example: If you have a link that opens a new window, without giving that person the opportunity to decide if it opens in the same window, then your users will be lost and unsure how to get back to the original page.
  2. Keep it consistent: Navigation should not change drastically within a related set of pages. Nor should interactions change functionality. 
    1. Example: If the Home link was at the bottom of one page, it should be at the bottom of a related page.
    2. Example: If text on a dark bar or panel expands information on a page, a similar text on a dark bar or panel should not take someone to a new page.