This is one of the largest and most varied disability categories, and the practical accessibility needs vary accordingly, but common helpful practices include plain, clear language, consistent and predictable navigation and page layout, breaking complex processes into smaller steps, avoiding unnecessary time limits, and providing clear, specific error messages rather than vague ones.
WCAG 2.2 added several success criteria aimed specifically at this group, including requirements around consistent help placement and not requiring users to solve a cognitive puzzle purely to prove they are not a robot, reflecting a growing recognition that cognitive accessibility had been comparatively under-addressed in earlier WCAG versions.