Interface Consistency

Interface consistency is a design principle requiring that navigational mechanisms, visual layouts, and interactive components appear and behave in the same way across different pages, screens, or applications. In accessibility, consistency is critical because users who rely on screen readers, keyboard navigation, or other assistive technologies build mental models of where elements are located and how interactions work — inconsistent placement or behavior forces them to relearn the interface on every screen. WCAG addresses this directly: Success Criterion 3.2.3 (Consistent Navigation) requires that navigation mechanisms repeated across pages occur in the same relative order, and Success Criterion 3.2.4 (Consistent Identification) requires that components with the same function are identified consistently. The transition from physical keypad phones to touchscreen smartphones dramatically reduced interface consistency for blind users, as each app introduces its own layout, gesture vocabulary, and navigation hierarchy.